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  • Speaker Prep Tip: Use the AV Studio Built into that Laptop

    - by merrillaldrich
    Over at erinstellato.com there is a great post this week about tips for new presenters. Ms. Stellato suggests, insightfully, that we record ourselves, which is really a fantastic piece of advice. What’s extra-cool is that today you don’t need any special equipment or expensive software to do just that. This week I “filmed” two run-throughs of my talk for SQL Saturday tomorrow. For me, the timing is the hardest thing – figuring out how much content I can really present in the time allowed without...(read more)

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  • Is there a more efficient way to filter large arrays than preg_match()?

    - by hozza
    I have a log that our web application builds. Each month it contains around 16,000 entries of a string with about the average sentence worth of text. To filter/search through these in our admin panel the script uses preg_match() but this seems to be taking ages and timing out on the 30sec limit. I have isolated that it is indeed the preg_match() that causes the time out. Is there a more efficient way to search through values in a large array for a users input?

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  • Is a 1:* write:read thread system safe?

    - by Di-0xide
    Theoretically, thread-safe code should fix race conditions. Race conditions, as I understand it, occur because two threads attempt to write to the same location at the same time. However, what about a threading model in which a single thread is designed to write to a location, and several slave/worker threads simply read from the location? Assuming the value/timing at which they read the data isn't relevant/doesn't hinder the worker thread's outcome, wouldn't this be considered 'thread safe', or am I missing something in my logic?

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  • Problem Installing Ubuntu on nexus 7

    - by jdl117
    Well, a good chunk of my day has been spent on what was supposed to take minutes... here's the rundown every time, i get stuck while flashing the root file system (freezing, timing out, or error message) i seemingly followed all of the steps and troubleshoots, and repeated them, no such luck. i would not count it out that i still messed one of them up, but does anyone have any ideas? on a side note while i am posting something, anyone know if android bluetooth keyboards play nicely with this ubuntu? i would guess not

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  • webserver horrible slow, sometimes incredible fast

    - by dhanke
    i am running a small community ( 6000+ Members ) on a non-virtual 64-bit ubuntu 11.04 system. I am not a Linux-pro, not even advanced, i just tried to setup a webserver, which does nothing special actually. Delivering some dynamic PHP and RoR websites is its task. So it might be that my configuration files do look horrible bad. Also, i might use the wrong vocabulary, so in doubt, please ask. Having a current all-time record of 520 registered users (board-accounts, no system-users) online at same time, average server-load is about 2.0 - 5.0. Meantime (~250 users) average server load value is at about 0.4 - 0.8, sometimes, on some expensive searches a bit higher. everything fine. From time to time however, the load increases up to 120 (120.0, not 12.0 ;) ). In this time, its hard to even connect via SSH, but when i reach the server, and use top/htop/iotop to see whats happening, i cannot identify any process causing high CPU load. iotop tells me about a current reading/writing speed of about approx. 70kb/s, which is quite equal to power-off i think. Memory-Usage is max. at ~ 12GB of 16GB, so swap remains empty. now the odd (at least for me:) waiting some minutes ( since i always get a bit into a panic when this happens, it feels like 5 minutes, but i suppose its more like 20-30 minutes) and the server is back to normal. everything continues as normal. another odd fact: when i run hdparm -tT /dev/sda, i get answer like: /dev/sda: Timing cached reads: 7180 MB in 2.00 seconds = 3591.13 MB/sec Timing buffered disk reads: 348 MB in 3.02 seconds = 115.41 MB/sec when i run the same command while the server is "frozen", the answer is like /dev/sda: <- takes about 5 minutes until this line appears Timing cached reads: 7180 MB in 2.00 seconds = 3591.13 MB/sec <- 5 more minutes Timing buffered disk reads: 348 MB in 3.02 seconds = 115.41 MB/sec <- another 5 minutes so the values are the same, but the quoted time is completely wrong. using time command as prefix also tells me that ~ 15 minutes were used. I searched in dmesg, /var/log/[messages|syslog] - nothing found. /var/log/errors however tells me that: Jul 4 20:28:30 localhost kernel: [19080.671415] INFO: task php5-fpm:27728 blocked for more than 120 seconds. Jul 4 20:28:30 localhost kernel: [19080.671419] "echo 0 /proc/sys/kernel/hung_task_timeout_secs" disables this message. multiple times. now that message does tell me that php5-fpm task was blocked or did block ? - but not if that is the cause or just one of the results of that "freeze". Anyone? to cut the long story short, i dont know where even to start analyzing. So if you can give me any advice by looking at following specs and configs, or ask me to provide more information, i`d be glad. Specs: 6 Core AMD Phenom(tm) II X6 1055T Processor * 16 Gigabyte Ram 2x 1.5 TB Seagate ST1500DL003-9VT16L via SATA 3 via SoftwareRaid (i suppose) Services: (due to service --status-all, those with [ + ]) nginx Webserver 1.0.14 mySQL 5.1.63 Server Ruby on Rails 2.3.11 ( passenger-nginx-module ) php5-fpm 5.3.6-13ubuntu3.7 SSH ido2db Further services: default crontab + nightly backup. syslog-ng Website consists of 2 subdomains, forum. and www. where forum is a phpBB3.x PHP-Board, and www a Ruby on Rails 2.3.11 application (portal). Mini-Note: sometimes i notice that the forum is pretty slow, in contrast to the always-fast (except for this "freeze") portal. Both share the same Database, but the portal is using it read-only. The Webserver is nginx, using phusion passenger module to communicate with the ruby-application. Also, for the forum it communicates with php5-fpm via socket: relevant nginx configuration parts ( with comments/questions starting by ; ) ; in case of freeze due to too high Filesystem activity, maybe adding a limit? #worker_rlimit_nofile 50000; user www-data; ; 6 cores, so i read 6 fits. maybe already wrong? worker_processes 6; pid /var/run/nginx.pid; events { worker_connections 1024; } http { passenger_root /var/lib/gems/1.8/gems/passenger-3.0.11; passenger_ruby /usr/bin/ruby1.8; ; the forum once featured a chat, which was working w/o websockets. ; so it was a hell of pull requests (deactivated now, freeze still happening) keepalive_timeout 65; keepalive_requests 50; gzip on; server { listen 80; server_name www.domain.tld; root /var/www/domain/rails/public; passenger_enabled on; } server { listen 80; server_name forum.domain.tld; location / { root /var/www/domain/forum; index index.php; } ; satic stuff to be handled by nginx location ~* ^/style/.+.(jpg|jpeg|gif|css|png|js|ico|xml)$ { access_log off; expires 30d; root /var/www/domain/forum/; } ; now the php magic, note the "backend"-fcgi_pass location ~ .php$ { fastcgi_split_path_info ^(.+\.php)(.*)$; fastcgi_pass backend; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME /var/www/domain/forum$fastcgi_script_name; include fastcgi_params; fastcgi_param QUERY_STRING $query_string; fastcgi_param REQUEST_METHOD $request_method; fastcgi_param CONTENT_TYPE $content_type; fastcgi_param CONTENT_LENGTH $content_length; fastcgi_intercept_errors on; fastcgi_ignore_client_abort off; fastcgi_connect_timeout 60; fastcgi_send_timeout 180; fastcgi_read_timeout 180; fastcgi_buffer_size 128k; fastcgi_buffers 256 16k; fastcgi_busy_buffers_size 256k; fastcgi_temp_file_write_size 256k; fastcgi_max_temp_file_size 0; } location ~ /\.ht { deny all; } } ;the php5-fpm socket. i read that /dev/shm/ whould be the fastes place for this. bad idea in general? upstream backend { server unix:/dev/shm/phpfpm; } ... } php5-fpm settings (i changed this values due to php5-fpm error log messages higher and higher.. (freeze-problem was there before as well)* listen = /dev/shm/phpfpm user = www-data group = www-data pm = dynamic ; holy, 4000! well, shinking this value to earth-level gave me ; 100s of 502 bad gateway commands. this values were quite stable. ; since there are only max 520 users online i dont get it, why i would need ; as many children as configured here. due to keep-alive maybe? ; asking questions is easier for me since restarting server will make ; my community-members angry ;) pm.max_children = 4000 pm.start_servers = 100 pm.min_spare_servers = 50 pm.max_spare_servers = 150 pm.max_requests = 10 pm.status_path = /status ping.path = /ping ping.response = pong slowlog = log/$pool.log.slow ;should i use rlimit? ;rlimit_files = 1024 chdir = / mysql/my.cnf [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp skip-external-locking bind-address = 127.0.0.1 key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 myisam-recover = BACKUP ; high number, but less gives some phpBB errors. max_connections = 450 table_cache = 512 ; i read twice the cpu cores, bad? thread_concurrency = 12 join_buffer_size = 2084K concurrent_insert = 3 query_cache_limit = 64M query_cache_size = 512M query_cache_type = 1 log_error = /var/log/mysql/error.log log_slow_queries = /var/log/mysql/mysql-slow.log long_query_time = 2 expire_logs_days = 10 max_binlog_size = 100M low_priority_updates=1 [mysqldump] quick quote-names max_allowed_packet = 16M [isamchk] key_buffer = 16M !includedir /etc/mysql/conf.d/ I used smartctl already, hdds seem to be fine. /proc/mdstatus quotes: Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md3 : active raid1 sda3[1] 1459264192 blocks [2/1] [_U] md1 : active raid1 sda1[0] 3911680 blocks [2/1] [U_] unused devices: ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 127727 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 127727 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited I quote some questions in my configuration files, these are not (intentional) directly problem-related, but would be nice for me to know wether they are indeed questionable or done right. One additional Fact: my MYSQL-database is at 12GB size. i dont know if that does matter, but mytop sometimes shows me 4-5 seconds long insert queries, some are 20-30 seconds long. Its just a feeling that i am unable to prove (because i dont know how), but when i disable the database, the freeze seems not to happen. Example: i created a dummy rails application to see the development log. the app made some sql-queries, reads and inserts. the log quite often was like: DbTest Load (0.3ms) SELECT * FROM `db_test` WHERE (`db_test`.`id` = 31722) LIMIT 1 SQL (0.1ms) BEGIN DbTest Update (0.3ms) UPDATE `db_test` SET `updated_at` = '2012-07-04 23:32:34' WHERE `id` = 31722 - now the log stands still for 5-60 seconds. SQL (49.1ms) COMMIT - SQL-Update time in the log does not include freeze time Rendering test/index Completed in 96ms (View: 16, DB: 59) | 200 OK [http://localhost:9000/test] Bad part is: this mini-freeze here only happens from time to time as well. note: meanwhile i cannot even upload files via scp. I currently feel like running form bad to worse and back by googling for my server-problem due to immense lack of knowledge regarding server configurations. It still makes me wonder, why those problems even appear, since 250 users a time is not such a high amount, right? So my questions: whats wrong and how to fix? ;) or: what information can i provide to make the situation more clear? can you point at some critical bad configuration-line which i should consider to catch up in the documentation? are there any tools i can run to see some possible bottlenecks? any further advice? (next to: "pay someone who knows what he does" - its a private project, server costs enough already. :)) Thanks for your time and help. Best Regards, Daniel P.S.: i renamed the configfiles to domain.tld since i dont want to have any % more load to the server until its fixed. might be a exaggeratedly thought.. P.P.S: if i asked a complete duplicate question, sorry. my search results seemed to be quite specific in their own way.

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  • different nmap results

    - by aasasas
    Hello I have a scan on my server form outside and from inside, why results are different? [root@xxx ~]# nmap -sV -p 0-65535 localhost Starting Nmap 5.51 ( http://nmap.org ) at 2011-02-16 07:59 MSK Nmap scan report for localhost (127.0.0.1) Host is up (0.000015s latency). rDNS record for 127.0.0.1: localhost.localdomain Not shown: 65534 closed ports PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 4.3 (protocol 2.0) 80/tcp open http Apache httpd 2.2.3 ((CentOS)) Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 7.99 seconds AND sh-3.2# nmap -sV -p 0-65535 xxx.com Starting Nmap 5.51 ( http://nmap.org ) at 2011-02-16 00:01 EST Warning: Unable to open interface vmnet1 -- skipping it. Warning: Unable to open interface vmnet8 -- skipping it. Stats: 0:07:49 elapsed; 0 hosts completed (1 up), 1 undergoing SYN Stealth Scan SYN Stealth Scan Timing: About 36.92% done; ETC: 00:22 (0:13:21 remaining) Stats: 0:22:05 elapsed; 0 hosts completed (1 up), 1 undergoing Service Scan Service scan Timing: About 75.00% done; ETC: 00:23 (0:00:02 remaining) Nmap scan report for xxx.com (x.x.x.x) Host is up (0.22s latency). Not shown: 65528 closed ports PORT STATE SERVICE VERSION 21/tcp open tcpwrapped 22/tcp open ssh OpenSSH 4.3 (protocol 2.0) 25/tcp open tcpwrapped 80/tcp open http Apache httpd 2.2.3 ((CentOS)) 110/tcp open tcpwrapped 143/tcp open tcpwrapped 443/tcp open tcpwrapped 8080/tcp open http-proxy?

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  • explanation of RAM specs, and what do I need for a Gaming rig

    - by ewok
    I am looking into upgrading my custom built PC's RAM. I use the machine mostly for gaming, but I don't really know a ton about RAM, so I wanted to ask a few questions. The research I've done tells me there is a negligible increase in speed for anything above 1600 MHz. is this true or is it worth the extra money to go higher? Other than drawing more power from the PSU, is there any real difference in performance with different voltages (1.5V vs 1.65V)? most of the kits I've found in the 2x4 1600 range have a CAS latency of 9 and timing of 9-9-9-24. For a significant increase in price (usually about 1.5x), I can get either 8 or 7 and lower timing. Is it worth the cost? What I am looking for here is someone to give a good explanation of what the different specs represent, and how that relates to the performance of the machine. Specifically, I'm looking for what specs I need to focus on for a good gaming rig. I am NOT looking for a "buy this, it's the best RAM" without an explanation of why. The information will be much more valuable as it will allow me to make my own informed decision. As they say, give a man a fish, he'll eat for a day. teach a man to fish, and he'll eat for the rest of his life.

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  • sql server 2005 instance unresponsive and all db's are 'in recovery'

    - by user44650
    we've got a sql server 2005 instance that one of our guys messed up, i believe they killed the sql server service and restarted the computer, and when it came back all of our databases are "in recovery" and it times out every time we try to connect to it. it's been 'in recovery'and unable to connect to 'msbd' (also in recovery) whenever we try to use SSMC, for the last 4 days now. i'm unsure how to use the DBCC CHECKDB command to check the db integrity. we have backups(which we can't recover from because it keeps timing out), and it's a testing server, so nothing in production is really lost. is there any way to get it out of recovery mode? we have another sqlserver instance running that's just fine, but this instance keeps timing out. the errors i keep seeing are database msdb is being recovered. wait until recovery is finished and an exception occurred while executing a transact-sql statement or batch Timeout expired. any thoughts? we don't really have a DBA here, or anyone with much sql experience.

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  • Why am I experiencing random connection timeouts? (CentOS)

    - by Ryan
    I have a CentOS server setup that currently hosts several websites (all relative of each other in some form or another). As of recently throughout the day at the most random times the website speed will lag to a crawl and eventually hit a connection timeout. When I say random times this typically happens anywhere between 10am and 1pm usually, however, this morning this happened to me at 8am. I do not have a lot of familiarity with server knowledge as far as what I am looking for in this situation. What are some possible causes of why my server is slowing the websites down to a complete crawl or timing out? Are there specific things I should be checking for when this happens? I have noticed using: tail /var/log/httpd/access_log That usually when this down time occurs there are lot of IP addresses related to BingBot, Googlebot, and sometimes various bots or spiders that I am unfamiliar with. Could this be related and if so how can I avoid this from causing my websites to lag out? Thanks in advance for any help or advice. The websites that are timing out are built with PHP and use a MySQL database to display information.

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  • mdadm lvm and ext4 slowness - How can I speed it up?

    - by beatbreaker
    I can't figure out why I'm getting such terrible times out of my mdadm and in particular the lvm partitions in it. I made the raid: mdadm --create --verbose /dev/md0 --level=5 --chunk=1024 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 # cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid5 sda1[0] sdd1[3] sdc1[2] sdb1[1] 2930279424 blocks level 5, 1024k chunk, algorithm 2 [4/4] [UUUU] I then created the physical volume, volume group, and logical volumes, I then formatted the logical volumes to ext4 using the following commands I got from here: http://busybox.net/~aldot/mkfs_stride.html mkfs.ext3 -b 4096 -E stride=256,stripe-width=768 /dev/datavg/blah Now I'm confused, I had these lvs running real quick before in mdadm but now that I've 'optimized' everything it's slower, eg, before: /dev/datavg/lv_audio: Timing buffered disk reads: 598 MB in 3.01 seconds = 198.85 MB/sec but now after: /dev/datavg/audio: Timing buffered disk reads: 198 MB in 3.00 seconds = 65.96 MB/sec That's pitiful! What's happened here? Did I not follow the instructions correctly? Can i reshape the ext4 partitons to default back to what they were? (I used defaults before and they were fine!)

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  • Performance Optimization &ndash; It Is Faster When You Can Measure It

    - by Alois Kraus
    Performance optimization in bigger systems is hard because the measured numbers can vary greatly depending on the measurement method of your choice. To measure execution timing of specific methods in your application you usually use Time Measurement Method Potential Pitfalls Stopwatch Most accurate method on recent processors. Internally it uses the RDTSC instruction. Since the counter is processor specific you can get greatly different values when your thread is scheduled to another core or the core goes into a power saving mode. But things do change luckily: Intel's Designer's vol3b, section 16.11.1 "16.11.1 Invariant TSC The time stamp counter in newer processors may support an enhancement, referred to as invariant TSC. Processor's support for invariant TSC is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run at a constant rate in all ACPI P-, C-. and T-states. This is the architectural behavior moving forward. On processors with invariant TSC support, the OS may use the TSC for wall clock timer services (instead of ACPI or HPET timers). TSC reads are much more efficient and do not incur the overhead associated with a ring transition or access to a platform resource." DateTime.Now Good but it has only a resolution of 16ms which can be not enough if you want more accuracy.   Reporting Method Potential Pitfalls Console.WriteLine Ok if not called too often. Debug.Print Are you really measuring performance with Debug Builds? Shame on you. Trace.WriteLine Better but you need to plug in some good output listener like a trace file. But be aware that the first time you call this method it will read your app.config and deserialize your system.diagnostics section which does also take time.   In general it is a good idea to use some tracing library which does measure the timing for you and you only need to decorate some methods with tracing so you can later verify if something has changed for the better or worse. In my previous article I did compare measuring performance with quantum mechanics. This analogy does work surprising well. When you measure a quantum system there is a lower limit how accurately you can measure something. The Heisenberg uncertainty relation does tell us that you cannot measure of a quantum system the impulse and location of a particle at the same time with infinite accuracy. For programmers the two variables are execution time and memory allocations. If you try to measure the timings of all methods in your application you will need to store them somewhere. The fastest storage space besides the CPU cache is the memory. But if your timing values do consume all available memory there is no memory left for the actual application to run. On the other hand if you try to record all memory allocations of your application you will also need to store the data somewhere. This will cost you memory and execution time. These constraints are always there and regardless how good the marketing of tool vendors for performance and memory profilers are: Any measurement will disturb the system in a non predictable way. Commercial tool vendors will tell you they do calculate this overhead and subtract it from the measured values to give you the most accurate values but in reality it is not entirely true. After falling into the trap to trust the profiler timings several times I have got into the habit to Measure with a profiler to get an idea where potential bottlenecks are. Measure again with tracing only the specific methods to check if this method is really worth optimizing. Optimize it Measure again. Be surprised that your optimization has made things worse. Think harder Implement something that really works. Measure again Finished! - Or look for the next bottleneck. Recently I have looked into issues with serialization performance. For serialization DataContractSerializer was used and I was not sure if XML is really the most optimal wire format. After looking around I have found protobuf-net which uses Googles Protocol Buffer format which is a compact binary serialization format. What is good for Google should be good for us. A small sample app to check out performance was a matter of minutes: using ProtoBuf; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.Serialization; [DataContract, Serializable] class Data { [DataMember(Order=1)] public int IntValue { get; set; } [DataMember(Order = 2)] public string StringValue { get; set; } [DataMember(Order = 3)] public bool IsActivated { get; set; } [DataMember(Order = 4)] public BindingFlags Flags { get; set; } } class Program { static MemoryStream _Stream = new MemoryStream(); static MemoryStream Stream { get { _Stream.Position = 0; _Stream.SetLength(0); return _Stream; } } static void Main(string[] args) { DataContractSerializer ser = new DataContractSerializer(typeof(Data)); Data data = new Data { IntValue = 100, IsActivated = true, StringValue = "Hi this is a small string value to check if serialization does work as expected" }; var sw = Stopwatch.StartNew(); int Runs = 1000 * 1000; for (int i = 0; i < Runs; i++) { //ser.WriteObject(Stream, data); Serializer.Serialize<Data>(Stream, data); } sw.Stop(); Console.WriteLine("Did take {0:N0}ms for {1:N0} objects", sw.Elapsed.TotalMilliseconds, Runs); Console.ReadLine(); } } The results are indeed promising: Serializer Time in ms N objects protobuf-net   807 1000000 DataContract 4402 1000000 Nearly a factor 5 faster and a much more compact wire format. Lets use it! After switching over to protbuf-net the transfered wire data has dropped by a factor two (good) and the performance has worsened by nearly a factor two. How is that possible? We have measured it? Protobuf-net is much faster! As it turns out protobuf-net is faster but it has a cost: For the first time a type is de/serialized it does use some very smart code-gen which does not come for free. Lets try to measure this one by setting of our performance test app the Runs value not to one million but to 1. Serializer Time in ms N objects protobuf-net 85 1 DataContract 24 1 The code-gen overhead is significant and can take up to 200ms for more complex types. The break even point where the code-gen cost is amortized by its faster serialization performance is (assuming small objects) somewhere between 20.000-40.000 serialized objects. As it turned out my specific scenario involved about 100 types and 1000 serializations in total. That explains why the good old DataContractSerializer is not so easy to take out of business. The final approach I ended up was to reduce the number of types and to serialize primitive types via BinaryWriter directly which turned out to be a pretty good alternative. It sounded good until I measured again and found that my optimizations so far do not help much. After looking more deeper at the profiling data I did found that one of the 1000 calls did take 50% of the time. So how do I find out which call it was? Normal profilers do fail short at this discipline. A (totally undeserved) relatively unknown profiler is SpeedTrace which does unlike normal profilers create traces of your applications by instrumenting your IL code at runtime. This way you can look at the full call stack of the one slow serializer call to find out if this stack was something special. Unfortunately the call stack showed nothing special. But luckily I have my own tracing as well and I could see that the slow serializer call did happen during the serialization of a bool value. When you encounter after much analysis something unreasonable you cannot explain it then the chances are good that your thread was suspended by the garbage collector. If there is a problem with excessive GCs remains to be investigated but so far the serialization performance seems to be mostly ok.  When you do profile a complex system with many interconnected processes you can never be sure that the timings you just did measure are accurate at all. Some process might be hitting the disc slowing things down for all other processes for some seconds as well. There is a big difference between warm and cold startup. If you restart all processes you can basically forget the first run because of the OS disc cache, JIT and GCs make the measured timings very flexible. When you are in need of a random number generator you should measure cold startup times of a sufficiently complex system. After the first run you can try again getting different and much lower numbers. Now try again at least two times to get some feeling how stable the numbers are. Oh and try to do the same thing the next day. It might be that the bottleneck you found yesterday is gone today. Thanks to GC and other random stuff it can become pretty hard to find stuff worth optimizing if no big bottlenecks except bloatloads of code are left anymore. When I have found a spot worth optimizing I do make the code changes and do measure again to check if something has changed. If it has got slower and I am certain that my change should have made it faster I can blame the GC again. The thing is that if you optimize stuff and you allocate less objects the GC times will shift to some other location. If you are unlucky it will make your faster working code slower because you see now GCs at times where none were before. This is where the stuff does get really tricky. A safe escape hatch is to create a repro of the slow code in an isolated application so you can change things fast in a reliable manner. Then the normal profilers do also start working again. As Vance Morrison does point out it is much more complex to profile a system against the wall clock compared to optimize for CPU time. The reason is that for wall clock time analysis you need to understand how your system does work and which threads (if you have not one but perhaps 20) are causing a visible delay to the end user and which threads can wait a long time without affecting the user experience at all. Next time: Commercial profiler shootout.

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  • Organizations &amp; Architecture UNISA Studies &ndash; Chap 7

    - by MarkPearl
    Learning Outcomes Name different device categories Discuss the functions and structure of I/.O modules Describe the principles of Programmed I/O Describe the principles of Interrupt-driven I/O Describe the principles of DMA Discuss the evolution characteristic of I/O channels Describe different types of I/O interface Explain the principles of point-to-point and multipoint configurations Discuss the way in which a FireWire serial bus functions Discuss the principles of InfiniBand architecture External Devices An external device attaches to the computer by a link to an I/O module. The link is used to exchange control, status, and data between the I/O module and the external device. External devices can be classified into 3 categories… Human readable – e.g. video display Machine readable – e.g. magnetic disk Communications – e.g. wifi card I/O Modules An I/O module has two major functions… Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links Module Functions The major functions or requirements for an I/O module fall into the following categories… Control and timing Processor communication Device communication Data buffering Error detection I/O function includes a control and timing requirement, to coordinate the flow of traffic between internal resources and external devices. Processor communication involves the following… Command decoding Data Status reporting Address recognition The I/O device must be able to perform device communication. This communication involves commands, status information, and data. An essential task of an I/O module is data buffering due to the relative slow speeds of most external devices. An I/O module is often responsible for error detection and for subsequently reporting errors to the processor. I/O Module Structure An I/O module functions to allow the processor to view a wide range of devices in a simple minded way. The I/O module may hide the details of timing, formats, and the electro mechanics of an external device so that the processor can function in terms of simple reads and write commands. An I/O channel/processor is an I/O module that takes on most of the detailed processing burden, presenting a high-level interface to the processor. There are 3 techniques are possible for I/O operations Programmed I/O Interrupt[t I/O DMA Access Programmed I/O When a processor is executing a program and encounters an instruction relating to I/O it executes that instruction by issuing a command to the appropriate I/O module. With programmed I/O, the I/O module will perform the requested action and then set the appropriate bits in the I/O status register. The I/O module takes no further actions to alert the processor. I/O Commands To execute an I/O related instruction, the processor issues an address, specifying the particular I/O module and external device, and an I/O command. There are four types of I/O commands that an I/O module may receive when it is addressed by a processor… Control – used to activate a peripheral and tell it what to do Test – Used to test various status conditions associated with an I/O module and its peripherals Read – Causes the I/O module to obtain an item of data from the peripheral and place it in an internal buffer Write – Causes the I/O module to take an item of data form the data bus and subsequently transmit that data item to the peripheral The main disadvantage of this technique is it is a time consuming process that keeps the processor busy needlessly I/O Instructions With programmed I/O there is a close correspondence between the I/O related instructions that the processor fetches from memory and the I/O commands that the processor issues to an I/O module to execute the instructions. Typically there will be many I/O devices connected through I/O modules to the system – each device is given a unique identifier or address – when the processor issues an I/O command, the command contains the address of the address of the desired device, thus each I/O module must interpret the address lines to determine if the command is for itself. When the processor, main memory and I/O share a common bus, two modes of addressing are possible… Memory mapped I/O Isolated I/O (for a detailed explanation read page 245 of book) The advantage of memory mapped I/O over isolated I/O is that it has a large repertoire of instructions that can be used, allowing more efficient programming. The disadvantage of memory mapped I/O over isolated I/O is that valuable memory address space is sued up. Interrupts driven I/O Interrupt driven I/O works as follows… The processor issues an I/O command to a module and then goes on to do some other useful work The I/O module will then interrupts the processor to request service when is is ready to exchange data with the processor The processor then executes the data transfer and then resumes its former processing Interrupt Processing The occurrence of an interrupt triggers a number of events, both in the processor hardware and in software. When an I/O device completes an I/O operations the following sequence of hardware events occurs… The device issues an interrupt signal to the processor The processor finishes execution of the current instruction before responding to the interrupt The processor tests for an interrupt – determines that there is one – and sends an acknowledgement signal to the device that issues the interrupt. The acknowledgement allows the device to remove its interrupt signal The processor now needs to prepare to transfer control to the interrupt routine. To begin, it needs to save information needed to resume the current program at the point of interrupt. The minimum information required is the status of the processor and the location of the next instruction to be executed. The processor now loads the program counter with the entry location of the interrupt-handling program that will respond to this interrupt. It also saves the values of the process registers because the Interrupt operation may modify these The interrupt handler processes the interrupt – this includes examination of status information relating to the I/O operation or other event that caused an interrupt When interrupt processing is complete, the saved register values are retrieved from the stack and restored to the registers Finally, the PSW and program counter values from the stack are restored. Design Issues Two design issues arise in implementing interrupt I/O Because there will be multiple I/O modules, how does the processor determine which device issued the interrupt? If multiple interrupts have occurred, how does the processor decide which one to process? Addressing device recognition, 4 general categories of techniques are in common use… Multiple interrupt lines Software poll Daisy chain Bus arbitration For a detailed explanation of these approaches read page 250 of the textbook. Interrupt driven I/O while more efficient than simple programmed I/O still requires the active intervention of the processor to transfer data between memory and an I/O module, and any data transfer must traverse a path through the processor. Thus is suffers from two inherent drawbacks… The I/O transfer rate is limited by the speed with which the processor can test and service a device The processor is tied up in managing an I/O transfer; a number of instructions must be executed for each I/O transfer Direct Memory Access When large volumes of data are to be moved, an efficient technique is direct memory access (DMA) DMA Function DMA involves an additional module on the system bus. The DMA module is capable of mimicking the processor and taking over control of the system from the processor. It needs to do this to transfer data to and from memory over the system bus. DMA must the bus only when the processor does not need it, or it must force the processor to suspend operation temporarily (most common – referred to as cycle stealing). When the processor wishes to read or write a block of data, it issues a command to the DMA module by sending to the DMA module the following information… Whether a read or write is requested using the read or write control line between the processor and the DMA module The address of the I/O device involved, communicated on the data lines The starting location in memory to read from or write to, communicated on the data lines and stored by the DMA module in its address register The number of words to be read or written, communicated via the data lines and stored in the data count register The processor then continues with other work, it delegates the I/O operation to the DMA module which transfers the entire block of data, one word at a time, directly to or from memory without going through the processor. When the transfer is complete, the DMA module sends an interrupt signal to the processor, this the processor is involved only at the beginning and end of the transfer. I/O Channels and Processors Characteristics of I/O Channels As one proceeds along the evolutionary path, more and more of the I/O function is performed without CPU involvement. The I/O channel represents an extension of the DMA concept. An I/O channel ahs the ability to execute I/O instructions, which gives it complete control over I/O operations. In a computer system with such devices, the CPU does not execute I/O instructions – such instructions are stored in main memory to be executed by a special purpose processor in the I/O channel itself. Two types of I/O channels are common A selector channel controls multiple high-speed devices. A multiplexor channel can handle I/O with multiple characters as fast as possible to multiple devices. The external interface: FireWire and InfiniBand Types of Interfaces One major characteristic of the interface is whether it is serial or parallel parallel interface – there are multiple lines connecting the I/O module and the peripheral, and multiple bits are transferred simultaneously serial interface – there is only one line used to transmit data, and bits must be transmitted one at a time With new generation serial interfaces, parallel interfaces are becoming less common. In either case, the I/O module must engage in a dialogue with the peripheral. In general terms the dialog may look as follows… The I/O module sends a control signal requesting permission to send data The peripheral acknowledges the request The I/O module transfers data The peripheral acknowledges receipt of data For a detailed explanation of FireWire and InfiniBand technology read page 264 – 270 of the textbook

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  • XNA Health Bar continually decreasing

    - by Craig
    As per the Health bar tutorial on ... http://www.xnadevelopment.com/tutorials/notsohealthy/NotSoHealthy.shtml I have set up the above, how do I make it decrease by 1 health per second? I want to create a mini survival game, and this is an important factor. Where am i going wrong? I want it to visibly decrease every second. using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace Health { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D healthBar; int currentHealth = 100; float seconds; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); healthBar = Content.Load<Texture2D>("HealthBar"); // TODO: use this.Content to load your game content here } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { // Allows the game to exit if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); // TODO: Add your update logic here currentHealth = (int)MathHelper.Clamp(currentHealth, 0, 100); seconds += (float)gameTime.ElapsedGameTime.TotalSeconds; if (seconds >= 1) { currentHealth -= 1; } seconds = 0; base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(healthBar, new Rectangle(this.Window.ClientBounds.Width / 2 - healthBar.Width / 2, 30, healthBar.Width, 44), new Rectangle(0, 45, healthBar.Width, 44), Color.Gray); spriteBatch.Draw(healthBar, new Rectangle(this.Window.ClientBounds.Width / 2 - healthBar.Width / 2, 30, (int)(healthBar.Width * ((double)currentHealth / 100)), 44), new Rectangle(0, 45, healthBar.Width, 44), Color.Red); spriteBatch.Draw(healthBar, new Rectangle(this.Window.ClientBounds.Width / 2 - healthBar.Width / 2, 30, healthBar.Width, 44), new Rectangle(0, 0, healthBar.Width, 44), Color.White); spriteBatch.End(); base.Draw(gameTime); } } } Cheers!

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  • Inaccurate performance counter timer values in Windows Performance Monitor

    - by krisg
    I am implementing instrumentation within an application and have encountered an issue where the value that is displayed in Windows Performance Monitor from a PerformanceCounter is incongruent with the value that is recorded. I am using a Stopwatch to record the duration of a method execution, then first i record the total milliseconds as a double, and secondly i pass the Stopwatch's TimeSpan.Ticks to the PerformanceCounter to be recorded in the Performance Monitor. Creating the Performance Counters in perfmon: var datas = new CounterCreationDataCollection(); datas.Add(new CounterCreationData { CounterName = name, CounterType = PerformanceCounterType.AverageTimer32 }); datas.Add(new CounterCreationData { CounterName = namebase, CounterType = PerformanceCounterType.AverageBase }); PerformanceCounterCategory.Create("Category", "performance data", PerformanceCounterCategoryType.SingleInstance, datas); Then to record i retrieve a pre-initialized counter from a collection and increment: _counters[counter].IncrementBy(timing); _counters[counterbase].Increment(); ...where "timing" is the Stopwatch's TimeSpan.Ticks value. When this runs, the collection of double's, which are the milliseconds values for the Stopwatch's TimeSpan show one set of values, but what appears in PerfMon are a different set of values. For example... two values recorded in the List of milliseconds are: 23322.675, 14230.614 And what appears in PerfMon graph are: 15.546, 9.930 Can someone explain this please?

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  • Progress Bar design patterns?

    - by shoosh
    The application I'm writing performs a length algorithm which usually takes a few minutes to finish. During this time I'd like to show the user a progress bar which indicates how much of the algorithm is done as precisely as possible. The algorithm is divided into several steps, each with its own typical timing. For instance- initialization (500 milli-sec) reading inputs (5 sec) step 1 (30 sec) step 2 (3 minutes) writing outputs (7 sec) shutting down (10 milli-sec) Each step can report its progress quite easily by setting the range its working on, say [0 to 150] and then reporting the value it completed in its main loop. What I currently have set up is a scheme of nested progress monitors which form a sort of implicit tree of progress reporting. All progress monitors inherit from an interface IProgressMonitor: class IProgressMonitor { public: void setRange(int from, int to) = 0; void setValue(int v) = 0; }; The root of the tree is the ProgressMonitor which is connected to the actual GUI interface: class GUIBarProgressMonitor : public IProgressMonitor { GUIBarProgressMonitor(ProgressBarWidget *); }; Any other node in the tree are monitors which take control of a piece of the parent progress: class SubProgressMonitor : public IProgressMonitor { SubProgressMonitor(IProgressMonitor *parent, int parentFrom, int parentLength) ... }; A SubProgressMonitor takes control of the range [parentFrom, parentFrom+parentLength] of its parent. With this scheme I am able to statically divide the top level progress according to the expected relative portion of each step in the global timing. Each step can then be further subdivided into pieces etc' The main disadvantage of this is that the division is static and it gets painful to make changes according to variables which are discovered at run time. So the question: are there any known design patterns for progress monitoring which solve this issue?

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  • Perf4j Not Logging to Separate File

    - by Jehud
    I setup some stop watch calls in my code to measure some code blocks and all the messages are going into my primary log and not into the timing log. The perfStats.log file gets created just fine but all the messages go to the root log which I didn't think was supposed to happen according to the docs I've read. Is there something obvious I'm missing here? Example log4j.xml <!-- This file appender is used to output aggregated performance statistics --> <appender name="fileAppender" class="org.apache.log4j.FileAppender"> <param name="File" value="perfStats.log"/> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%m%n"/> </layout> </appender> <!-- Loggers --> <!-- The Perf4J logger. Note that org.perf4j.TimingLogger is the value of the org.perf4j.StopWatch.DEFAULT_LOGGER_NAME constant. Also, note that additivity is set to false, which is usually what is desired - this means that timing statements will only be sent to this logger and NOT to upstream loggers. --> <logger name="org.perf4j.TimingLogger" additivity="false"> <level value="INFO"/> <appender-ref ref="CoalescingStatistics"/> </logger> <root> <priority value="info"/> <appender-ref ref="STDOUT-DEBUG"/> </root>

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  • WCF Service timeout in Callback

    - by Muckers Mate
    I'm trying to get to grips with WCF, in particular writing a WCF Service application with callback. I've setup the service, together with the callback contract but when the callback is called, the app is timing out. Essentially, from a client I'm setting a property within the service class. The Setter of this property, if it fails validation fires a callback and, well, this is timing out. I realise that this is probably to it not being an Asynchronous calback, but can someone please show me how to resolve this? Thanks // The call back (client-side) interface public interface ISAPUploadServiceReply { [OperationContract(IsOneWay = true)] void Reply(int stateCode); } // The Upload Service interface [ServiceContract(CallbackContract = typeof(ISAPUploadServiceReply))] public interface ISAPUploadService { int ServerState { [OperationContract] get; [OperationContract(IsOneWay=true)] set; And the implementation... public int ServerState { get { return serverState; } set { if (InvalidState(Value)) { var to = OperationContext.Current.GetCallbackChannel<ISAPUploadServiceReply>(); to.Reply(eInvalidState); } else serverState = value; } }

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  • iphone - why is this flip animation using layers not working?

    - by Digital Robot
    I would like to make an animation that goes like this: imagine a picture sitting on a shelve. It drops from the shelve and as it falls it rotates along the horizontal axis and translates along the vertical axis. I would like to do this with perspective and the back side should be the image reversed, like the picture is a kind of slide. I have done this: CALayer* layer = myImageView.layer; layer.doubleSided = YES; CAKeyframeAnimation* animationTransform = [CAKeyframeAnimation animationWithKeyPath:@"transform"]; CATransform3D startTransform = CATransform3DIdentity; CATransform3D endTransform = CATransform3DTranslate (layer.transform, 0.0f, 200.0f, 0.0f); endTransform = CATransform3DRotate (endTransform, degreesToRadian(350.0f), 1.0f, 0.0f, 0.0f); endTransform.m34 = 1.0 / -500; NSArray *values = [NSArray arrayWithObjects: [NSValue valueWithCATransform3D:startTransform], [NSValue valueWithCATransform3D:endTransform], nil]; [animationTransform setValues:values]; NSArray *tempos = [NSArray arrayWithObjects: [NSNumber numberWithFloat:0.0f], [NSNumber numberWithFloat:0.7f], nil]; [animationTransform setKeyTimes:tempos]; NSArray *timing = [NSArray arrayWithObjects: [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut], nil]; [animationTransform setTimingFunctions:timing]; animationTransform.fillMode = kCAFillModeRemoved; animationTransform.removedOnCompletion = YES; animationTransform.repeatCount = 1; animationTransform.duration = 3.7f; animationTransform.cumulative = YES; the result of this has nothing to do with anything. The result is: the image translates down an inch on the screen and then up half inch. Then it disappears and appears at its starting position again. What am I missing? thanks

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  • Efficient way to remove empty lists from lists without evaluating held expressions?

    - by Alexey Popkov
    In previous thread an efficient way to remove empty lists ({}) from lists was suggested: Replace[expr, x_List :> DeleteCases[x, {}], {0, Infinity}] Using the Trott-Strzebonski in-place evaluation technique this method can be generalized for working also with held expressions: f1[expr_] := Replace[expr, x_List :> With[{eval = DeleteCases[x, {}]}, eval /; True], {0, Infinity}] This solution is more efficient than the one based on ReplaceRepeated: f2[expr_] := expr //. {left___, {}, right___} :> {left, right} But it has one disadvantage: it evaluates held expressions if they are wrapped by List: In[20]:= f1[Hold[{{}, 1 + 1}]] Out[20]= Hold[{2}] So my question is: what is the most efficient way to remove all empty lists ({}) from lists without evaluating held expressions? The empty List[] object should be removed only if it is an element of another List itself. Here are some timings: In[76]:= expr = Tuples[Tuples[{{}, {}}, 3], 4]; First@Timing[#[expr]] & /@ {f1, f2, f3} pl = Plot3D[Sin[x y], {x, 0, Pi}, {y, 0, Pi}]; First@Timing[#[pl]] & /@ {f1, f2, f3} Out[77]= {0.581, 0.901, 5.027} Out[78]= {0.12, 0.21, 0.18} Definitions: Clear[f1, f2, f3]; f3[expr_] := FixedPoint[ Function[e, Replace[e, {a___, {}, b___} :> {a, b}, {0, Infinity}]], expr]; f1[expr_] := Replace[expr, x_List :> With[{eval = DeleteCases[x, {}]}, eval /; True], {0, Infinity}]; f2[expr_] := expr //. {left___, {}, right___} :> {left, right};

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  • Bad motherboard / controller / HDs?

    - by quidpro
    On a leased server, I am running into some timing issues with an application that requires precise timing. Server is a Dual Xeon E5410 running on a Supermicro X7DVL-3 motherboard under CentOs 5.5 x64. The application I am running is timer sensitive and keeps sensing drift whether under load or at idle, but especially under load. I did some investigating with atop and dd and found some mind-blowing numbers. Mind you, I am no Linux guru but something sure seems out of whack. I ran: dd bs=4096 if=/dev/zero of=/bigtestfile to generate disk activity. Regardless whether I wrote it to sda or sdb my DSK value in atop would go over 100%, at one time peaking at 1700%. Again it does not matter if I am writing to sda or sdb. DSK | sdb | busy 675% | read 0 | write 110 | avio 78 ms | Here are the smartctl outputs: # smartctl -A /dev/sda smartctl version 5.38 [x86_64-redhat-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000b 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0007 165 165 021 Pre-fail Always - 2750 4 Start_Stop_Count 0x0032 100 100 040 Old_age Always - 21 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x000a 200 200 051 Old_age Always - 0 9 Power_On_Hours 0x0032 065 065 000 Old_age Always - 25831 10 Spin_Retry_Count 0x0012 100 253 051 Old_age Always - 0 11 Calibration_Retry_Count 0x0012 100 253 051 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 21 194 Temperature_Celsius 0x0022 116 093 000 Old_age Always - 27 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0012 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0012 200 200 000 Old_age Always - 0 199 UDMA_CRC_Error_Count 0x000a 200 253 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 051 Old_age Offline - 0 # smartctl -A /dev/sdb smartctl version 5.38 [x86_64-redhat-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0003 180 180 021 Pre-fail Always - 3958 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 22 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x000f 200 200 051 Pre-fail Always - 0 9 Power_On_Hours 0x0032 068 068 000 Old_age Always - 24087 10 Spin_Retry_Count 0x0013 100 253 051 Pre-fail Always - 0 11 Calibration_Retry_Count 0x0013 100 253 051 Pre-fail Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 21 194 Temperature_Celsius 0x0022 122 096 000 Old_age Always - 25 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0012 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0010 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x003e 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0009 200 200 051 Pre-fail Offline - 0 Any idea what's wrong here? Bad motherboard? It would seem rare that both drives are going bad (smartctl says they PASS_, so it leaves the mobo as the culprit in my eyes.

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  • Increase php session time via .htaccess not working

    - by Ken
    I want to create the session timeout to 6 hours but my browser is still timing out in 1/2 hour. I am on a PLESK server. I updated .htaccess php_value session.gc_maxlifetime 21600 php_value session.cache_expire 21600 php_value session.cookie_lifetime 21600 Here is the relevant PHPinfo: Local Master session.gc_maxlifetime 21600 1440 session.cache_expire 21600 180 session.gc_maxlifetime 21600 1440

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  • How to backup or export PowerStrip display profiles?

    - by Sk8erPeter
    I would like to save two of my saved PowerStrip display profiles. Earlier I set 720x540 resolution and some other settings (frequency, etc.) to another display device usually used in extended mode, which is now NOT connected: But when I go to "Advanced timing options", I see some different settings. I thought I could copy settings with the copy icon , but this way I would copy the wrong ones, not the predefined ones (with the 720x540 resolution): What is the best method to "export" these settings before formatting the hard drive?

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  • Cant access a remote server due mistake by setting firewall rule

    - by LMIT
    I need help due a my silly mistake! So for long time i have a dedicate server hosted by register.it Usually i access remotly to this server (Windows 2008 server) by Terminal Server. Today i wanted to block one site that continually send request to my server. So i was adding a new rule in the firewall (the native firewall on windows 2008 server), as i did many time, but this time, probably i was sleeping with my brain i add a general rules that stop everything! So i cant access to the server anymore, as no any users can browse the sites, nothing is working because this rule block everything. I know that is a silly mistake, no need to tell me :) so please what i can do ? The only 1 thing that my provider let me is reboot the server by his control panel, but this not help me in any way because the firewall block me again. i have administrator username and password, so what i really can do ? there are some trick some tecnique, some expert guru that can help me in this very bad situation ? UPDATE i follow the Tony suggest and i did a NMAP to check if some ports are open but look like all closed: NMAP RESULT Starting Nmap 6.00 ( http://nmap.org ) at 2012-05-29 22:32 W. Europe Daylight Time NSE: Loaded 93 scripts for scanning. NSE: Script Pre-scanning. Initiating Parallel DNS resolution of 1 host. at 22:32 Completed Parallel DNS resolution of 1 host. at 22:33, 13.00s elapsed Initiating SYN Stealth Scan at 22:33 Scanning xxx.xxx.xxx.xxx [1000 ports] SYN Stealth Scan Timing: About 29.00% done; ETC: 22:34 (0:01:16 remaining) SYN Stealth Scan Timing: About 58.00% done; ETC: 22:34 (0:00:44 remaining) Completed SYN Stealth Scan at 22:34, 104.39s elapsed (1000 total ports) Initiating Service scan at 22:34 Initiating OS detection (try #1) against xxx.xxx.xxx.xxx Retrying OS detection (try #2) against xxx.xxx.xxx.xxx Initiating Traceroute at 22:34 Completed Traceroute at 22:35, 6.27s elapsed Initiating Parallel DNS resolution of 11 hosts. at 22:35 Completed Parallel DNS resolution of 11 hosts. at 22:35, 13.00s elapsed NSE: Script scanning xxx.xxx.xxx.xxx. Initiating NSE at 22:35 Completed NSE at 22:35, 0.00s elapsed Nmap scan report for xxx.xxx.xxx.xxx Host is up. All 1000 scanned ports on xxx.xxx.xxx.xxx are filtered Too many fingerprints match this host to give specific OS details TRACEROUTE (using proto 1/icmp) HOP RTT ADDRESS 1 ... ... ... 13 ... 30 NSE: Script Post-scanning. Read data files from: D:\Program Files\Nmap OS and Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 145.08 seconds Raw packets sent: 2116 (96.576KB) | Rcvd: 61 (4.082KB) Question: The provider locally can access by username and password ?

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  • WMI Remote connection objsWbemLocator.ConnectServer

    - by Sam
    I have an issue when connecting to remote machines using the following: Set objWMIService = objSWbemLocator.ConnectServer _ (sIP, "root\CIMV2", strUser, strPassword, "MS_409", "ntlmdomain:" + sDomain, 128) the problem is that some machines are not timing out and the process hangs. Is there a way to cancel the connect and continue with the next ip? I'm using vbscript. Thanks, Sam

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  • RAID 50 24Port Fast Writes Slow Reads - Ubuntu

    - by James
    What is going on here?! I am baffled. serveradmin@FILESERVER:/Volumes/MercuryInternal/test$ sudo dd if=/dev/zero of=/Volumes/MercuryInternal/test/test.fs bs=4096k count=10000 10000+0 records in 10000+0 records out 41943040000 bytes (42 GB) copied, 57.0948 s, 735 MB/s serveradmin@FILESERVER:/Volumes/MercuryInternal/test$ sudo dd if=/Volumes/MercuryInternal/test/test.fs of=/dev/null bs=4096k count=10000 10000+0 records in 10000+0 records out 41943040000 bytes (42 GB) copied, 116.189 s, 361 MB/s OF NOTE: My RAID50 is 3 sets of 8 disks. - This might not be the best config for SPEED. OS: Ubuntu 12.04.1 x64 Hardware Raid: RocketRaid 2782 - 24 Port Controller HardDriveType: Seagate Barracuda ES.2 1TB Drivers: v1.1 Open Source Linux Drivers. So 24 x 1TB drives, partitioned using parted. Filesystem is ext4. I/O scheduler WAS noop but have changed it to deadline with no seemingly performance benefit/cost. serveradmin@FILESERVER:/Volumes/MercuryInternal/test$ sudo gdisk -l /dev/sdb GPT fdisk (gdisk) version 0.8.1 Partition table scan: MBR: protective BSD: not present APM: not present GPT: present Found valid GPT with protective MBR; using GPT. Disk /dev/sdb: 41020686336 sectors, 19.1 TiB Logical sector size: 512 bytes Disk identifier (GUID): 95045EC6-6EAF-4072-9969-AC46A32E38C8 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 41020686302 Partitions will be aligned on 2048-sector boundaries Total free space is 5062589 sectors (2.4 GiB) Number Start (sector) End (sector) Size Code Name 1 2048 41015625727 19.1 TiB 0700 primary To me this should be working fine. I can't think of anything that would be causing this other then fundamental driver errors? I can't seem to get much/if any higher then the 361MB a second, is this hitting the "SATA2" link speed, which it shouldn't given it is a PCIe2.0 card. Or maybe some cacheing quirk - I do have Write Back enabled. Does anyone have any suggestions? Tests for me to perform? Or if you require more information, I am happy to provide it! This is a video fileserver for editing machines, so we have a preference for FAST reads over writes. I was just expected more from RAID 50 and 24 drives together... EDIT: (hdparm results) serveradmin@FILESERVER:/Volumes/MercuryInternal$ sudo hdparm -Tt /dev/sdb /dev/sdb: Timing cached reads: 17458 MB in 2.00 seconds = 8735.50 MB/sec Timing buffered disk reads: 884 MB in 3.00 seconds = 294.32 MB/sec EDIT2: (config details) Also, I am using a RAID block size of 256K. I was told a larger block size is better for larger (in my case large video) files. EDIT3: (Bonnie++ Results. Would love some guidance with this!)

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