Search Results

Search found 97855 results on 3915 pages for 'code performance'.

Page 198/3915 | < Previous Page | 194 195 196 197 198 199 200 201 202 203 204 205  | Next Page >

  • Is this a DNS or server-side error?

    - by joshlfisher
    I am having difficulty accessing a specific website. (I get 500 Server fault errors) I can access this site on my iPhone when NOT connected to WiFi. I CANNOT access the site when connected to WiFi or via a Ethernet connection to my home network. I thought it might be a DNS issue, so I copied the DNSservers from a friend who has a different ISP, and has no problem access the site. No luck. Also tried some of the public DNS servers out there, again, with no luck. Does anyone have any idea on how to trace this issue?

    Read the article

  • Would you expect this error ?

    - by GrumpyOldDBA
    Now I know why, but what I'm thinking is that if I create an error should I get valid data returned? To explain, I was browsing through the dmvs for queries which might benefit from tuning and I identified a query with two clustered index scans ( table scans ). I don't know all the schema off by heart and I was looking for a select by a LoginID column. I assumed this would be numeric and promptly entered an integer value to examine the query plan, yeah I should have looked at the table definition...(read more)

    Read the article

  • Per-machine decentralised DNS caching - nscd/lwresd/etc

    - by Dan Carley
    Preface: We have caching resolvers at each of our geographic network locations. These are clustered for resiliency and their locality reduces the latency of internal requests generated by our servers. This works well. Except that a vast quantity of the requests seen over the wire are lookups for the same records, generated by applications which don't perform any DNS caching of their own. Questions: Is there a significant benefit to running lightweight caching daemons on the individual servers in order to reduce repeated requests from hitting the network? Does anyone have experience of using [u]nscd, lwresd or dnscache to do such a thing? Are there any other packages worth looking at? Any caveats to beware of? Besides the obvious, caching and negative caching stale results.

    Read the article

  • AIX network parameters to close TCP sockets of unplugged devices

    - by ADD Geek
    Hi there We have an AIX box, running what we call in banking "ATM Switch" not the ATM networking switch, but the bank ATM driver. where we have some ATM machines connected to two server processes. The problem is, when we disconnect any of these machines, the netstat -na| grep <port number> command shows that the socket established for this disconnected device is still established, we have to manually send a command from the software to make the socket aware that it is not live anymore. Is there a parameter on tcp level to make this connection aware within a minute or two that this device is not connected anymore? we had the following parameters set with root privileges: no -o tcp_keepidle=1000 no -o tcp_keepcnt=2 no -o tcp_keepintvl=150 no -o tcp_finwait2=100 it was originally having the default values. but even after we changed these parameters and restarted the server processes, the problem was still there.

    Read the article

  • Should "closed as duplicate" software programming be extreme or functional? [migrated]

    - by Web Developer
    I'm a web developer loving this site for it's potential, and it's Coffee look . I was reading a great question, that is this: click here and noticed 8 moderators tagged it as DUPLICATED! The question was closed! Obviously it isn't and I'm going to explain why if needed but it can be seen: the question is unique, is the case/story of a young who have SPECIFIC experience with C++ , VB and Assembler and asking, knowing this specifications an answer (It is not a general question like "hey I'm young can I do the programmer??") Let me know your opinion! do you think this question should or should not be closed? And let's think about also the people not only the "data" and "cases covered" ... do you think this is important too? or is better to keep a place where people doesn't count?

    Read the article

  • Why might apache2 use 100% of CPU at startup?

    - by QuantumMechanic
    This is apache 2.2.14 on SLES9. Out of nowhere (i.e. it had been working fine for ages) I am seeing apache2 suddenly start using 100% of the CPU at startup, and never completing startup. Nothing is getting written to /var/log/error_log (when it did back when things were OK). ps only shows the main httpd process and not any of the spawned threads. When things were OK, it would show the spawned threads. So it appears httpd is going into some sort of infinite loop right at startup and isn't even completing startup. It's not an issue of being overloaded by connections -- this happens even when nothing is trying to contact it. The config files haven't changed (or at least they haven't changed in a way that changed their last-modified time). I've tried added -e debug -E /var/log/apache2/startup_info to the command line, but nothing is put in the file. Any ideas what could be happening?

    Read the article

  • AFP, SMB, NFS which is the best data transfer protocol ?

    - by Kami
    I have a computer with large hard disks running Gentoo. I have to serve med/big files via a wired network to Apple devices (all of them running OS X). Which protocol is the best for the following needs ? : Speed Ease of use (by the clients and the server) Less limited (max file size, limited charset for filenames) Security

    Read the article

  • Nginx Slower than Apache??

    - by ichilton
    Hi, I've just setup 2x identical Rackspace Cloud instances and am doing some comparisons and benchmarks to compare Apache and Nginx. I'm testing with a 3.4k png file and initially 512MB server instances but have now moved to 1024MB server instances. I'm very surprised to see that whatever I try, Apache seems to consistently outperform Nginx....what am I doing wrong? Nginx: Server Software: nginx/0.8.54 Server Port: 80 Document Length: 3400 bytes Concurrency Level: 100 Time taken for tests: 2.320 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 3612000 bytes HTML transferred: 3400000 bytes Requests per second: 431.01 [#/sec] (mean) Time per request: 232.014 [ms] (mean) Time per request: 2.320 [ms] (mean, across all concurrent requests) Transfer rate: 1520.31 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 11 15.7 3 120 Processing: 1 35 76.9 20 1674 Waiting: 1 31 73.0 19 1674 Total: 1 46 79.1 21 1693 Percentage of the requests served within a certain time (ms) 50% 21 66% 39 75% 40 80% 40 90% 98 95% 136 98% 269 99% 334 100% 1693 (longest request) And Apache: Server Software: Apache/2.2.16 Server Port: 80 Document Length: 3400 bytes Concurrency Level: 100 Time taken for tests: 1.346 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 3647000 bytes HTML transferred: 3400000 bytes Requests per second: 742.90 [#/sec] (mean) Time per request: 134.608 [ms] (mean) Time per request: 1.346 [ms] (mean, across all concurrent requests) Transfer rate: 2645.85 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 1 3.7 0 27 Processing: 0 3 6.2 1 29 Waiting: 0 2 5.0 1 29 Total: 1 4 7.0 1 29 Percentage of the requests served within a certain time (ms) 50% 1 66% 1 75% 1 80% 1 90% 17 95% 19 98% 26 99% 27 100% 29 (longest request) I'm currently using worker_processes 4; and worker_connections 1024; but i've tried and benchmarked different values and see the same behaviour on all - I just can't get it to perform as well as Apache and from what i've read previously, i'm shocked about this! Can anyone give any advice? Thanks, Ian

    Read the article

  • Just to not to be ingnorant.

    - by atch
    Could anyone explain to me why is it that producers of processors claim that their processor can perform so many thousands (or millions) operations per second and yet typical program (Word, VS etc.) on my machine with 4GB, 3500hz starts with no less than 10sek. Have to mention that I've just formatted disk and tick any necessarry boxes to optimize my machine. So if for example outlook starts in 10 sek I wonder how many millions of operations have to be performed to run such program? Thanks

    Read the article

  • Running a VM off a USB 2.0 Flash Drive - Mac/Parallels/XP

    - by geerlingguy
    I use a MacBook Air as my primary machine, and the 128GB SSD means space is precious. To save about 10 GB, I've been running Parallels with a Windows XP VM off an external USB hard drive, which performs as well in everyday use as running the VM off the internal SSD. So, I bought a tiny 32GB USB 2.0 flash drive, plugged it into the MacBook Air, formatted it first as ExFAT (which was slow), then as Mac OS Extended (Journaled) (which was also slow), and copied over my VM file, and ran Parallels off it. My full experience is documented here: http://www.midwesternmac.com/blogs/jeff-geerling/running-windows-xp-vm Straight file copies are really fast — 30 MB/sec read (solid the whole time), and 10-11 MB/sec write (solid the whole time). But I noticed that once XP started running, the disk access rates were in the low KB ranges. Are USB flash drives really that poor at random access, or could I possibly be missing something (the format of the flash drive, etc.?)? Of note, I've tried the following, to no great effect: Formatting the drive as either ExFAT or Mac OS Extended (Journaled) Unplugging all other USB devices and turning off Bluetooth (which runs on the right-side-port USB bus). Plugging in the flash drive either direct in the right side port, or the left side port, or into a USB 2.0 hub

    Read the article

  • Big project layout : adding new feature on multiple sub-projects

    - by Shiplu
    I want to know how to manage a big project with many components with version control management system. In my current project there are 4 major parts. Web Server Admin console Platform. The web and server part uses 2 libraries that I wrote. In total there are 5 git repositories and 1 mercurial repository. The project build script is in Platform repository. It automates the whole building process. The problem is when I add a new feature that affects multiple components I have to create branch for each of the affected repo. Implement the feature. Merge it back. My gut feeling is "something is wrong". So should I create a single repo and put all the components there? I think branching will be easier in that case. Or I just do what I am doing right now. In that case how do I solve this problem of creating branch on each repository?

    Read the article

  • One network, two macbooks, one is fast and the other is slow

    - by Brendan
    I really need help for my friend. I know next to nothing about computers. My roommate and I both have macbook pros from the same year running OS X, are both connecting wirelessly to the same xfinity wifi, and while mine runs perfectly fine, my roommate complains that his works very slowly and times out every few seconds. I can't seem to figure out why this is. He is trying to get me to switch internet providers because he is convinced that it is their problem, but this cannot possibly be the issue since it works great on mine. He has an xbox hooked up to the wifi that he says also works poorly. I really can't see switching providers given that I am experiencing absolutely zero problems. How can I help my friend?

    Read the article

  • Cause of slow download speed on a particular EC2 instance?

    - by James
    I have a networking issue I'm trying to solve. I have two EC2 instances, same zone, same type. On one of the two EC2 instances (the 'bad' instance), the download speed is really poor (200k/s), while on the other (the 'good' instance), the download speed is fine, comfortable at 30M/s +). To clarify, I'm talking about downloading files to the EC2 instance while ssh'd into the server, e.g running wget with a large file. I've tried different files, including S3 objects and a large linux ISO from elsewhere. Running ethtool eth0 only returns 'Link detected: yes' for both. When running ifconfig, both return the same for most part, aside from how the good instance shows no error packets yet the bad instance shows many: UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:168372370 errors:5075643 dropped:0 overruns:0 frame:0 TX packets:122116480 errors:0 dropped:0 overruns:0 carrier:0 Both servers are configured the same, at least were supposed to be. How can I go about diagnosing the cause for the slow download speed? Is there anything particular to EC2 instances that could cause this? Having trouble knowing where to start. Thanks for any help!

    Read the article

  • Use a template to get alternate behaviour?

    - by Serge
    Is this a bad practice? const int sId(int const id); // true/false it doesn't matter template<bool i> const int sId(int const id) { return this->id = id; } const int MCard::sId(int const id){ MCard card = *this; this->id = id; this->onChange.fire(EventArgs<MCard&, MCard&>(*this, card)); return this->id; } myCard.sId(9); myCard.sId<true>(8); As you can see, my goal is to be able to have an alternative behaviour for sId. I know I could use a second parameter to the function and use a if, but this feels more fun (imo) and might prevent branch prediction (I'm no expert in that field). So, is it a valid practice, and/or is there a better approach?

    Read the article

  • How I might think like a hacker so that I can anticipate security vulnerabilities in .NET or Java before a hacker hands me my hat [closed]

    - by Matthew Patrick Cashatt
    Premise I make a living developing web-based applications for all form-factors (mobile, tablet, laptop, etc). I make heavy use of SOA, and send and receive most data as JSON objects. Although most of my work is completed on the .NET or Java stacks, I am also recently delving into Node.js. This new stack has got me thinking that I know reasonably well how to secure applications using known facilities of .NET and Java, but I am woefully ignorant when it comes to best practices or, more importantly, the driving motivation behind the best practices. You see, as I gain more prominent clientele, I need to be able to assure them that their applications are secure and, in order to do that, I feel that I should learn to think like a malevolent hacker. What motivates a malevolent hacker: What is their prime mover? What is it that they are most after? Ultimately, the answer is money or notoriety I am sure, but I think it would be good to understand the nuanced motivators that lead to those ends: credit card numbers, damning information, corporate espionage, shutting down a highly visible site, etc. As an extension of question #1--but more specific--what are the things most likely to be seeked out by a hacker in almost any application? Passwords? Financial info? Profile data that will gain them access to other applications a user has joined? Let me be clear here. This is not judgement for or against the aforementioned motivations because that is not the goal of this post. I simply want to know what motivates a hacker regardless of our individual judgement. What are some heuristics followed to accomplish hacker goals? Ultimately specific processes would be great to know; however, in order to think like a hacker, I would really value your comments on the broader heuristics followed. For example: "A hacker always looks first for the low-hanging fruit such as http spoofing" or "In the absence of a CAPTCHA or other deterrent, a hacker will likely run a cracking script against a login prompt and then go from there." Possibly, "A hacker will try and attack a site via Foo (browser) first as it is known for Bar vulnerability. What are the most common hacks employed when following the common heuristics? Specifics here. Http spoofing, password cracking, SQL injection, etc. Disclaimer I am not a hacker, nor am I judging hackers (Heck--I even respect their ingenuity). I simply want to learn how I might think like a hacker so that I may begin to anticipate vulnerabilities before .NET or Java hands me a way to defend against them after the fact.

    Read the article

  • How do you think about an Application Generator? [closed]

    - by Mehdi Sheyda
    I'm designing an application-generating application. It is an application that takes the requirements of customer as inputs , analyzes the requirements, creates classes and produces program files in C#. I am at the beginning of this project and have a long way to go with this application. Do you have an experience with designing similar kinds of projects? What risks might I encounter with this project?

    Read the article

  • limit linux background flush (dirty pages)

    - by korkman
    Background flushing in linux happens when either too much written data is pending (adjustable via /proc/sys/vm/dirty_background_ratio) or a timeout for pending writes is reached (/proc/sys/vm/dirty_expire_centisecs). Unless another limit is being hit (/proc/sys/vm/dirty_ratio), more written data may be cached. Further writes will block. In theory, this should create a background process writing out dirty pages without disturbing other processes. In practice, it does disturb any process doing uncached reading or synchronous writing. Badly. This is because the background flush actually writes at 100% device speed and any other device requests at this time will be delayed (because all queues and write-caches on the road are filled). Is there any way to limit the amount of requests per second the flushing process performs, or otherwise effectively prioritize other device I/O?

    Read the article

  • Simple tool to graph memory usage?

    - by dbr
    Is there a script that will show memory usage as a graph, for example as a pie-chart, with each process being being a separate slice? I'm not looking for something like Munin to graph memory usage over time, but rather show the memory usage per-process at a single point in time. To make my request even more obscure, it is for a headless server (so no X applications). The simplest way would be to write a PNG file, or possibly an HTML file (which could use Javascript to allow the filtering of processes, changing between graph-types and so on)

    Read the article

  • dd oflag=direct 5x fast

    - by César
    I have Centos 6.2 in server with this specs: 2xCPU 16 Core AMD Opteron 6282 SE 64GB RAM Raid controller H700 1GB cache NV - 2HD 74GB SAS 15Krpm RAID1 stripe 16k (OS Centos 6.2) sda - 4HD 146GB SAS 15Krpm RAID10 stripe 16k (ext4 bs 4096, no barriers) sdb -> /vol01 Raid controller H800 1GB cache nv - MD1200 12HD 300GB SAS 15Krpm RAID10 stripe 256k (For DB Postgres 8.3.18) (ext4 bs 4096, stride 64, stripe-width 384, no barriers) sdc -> /vol02 I'm benchmarking IO speed with dd, and view thah if in RAID10 12 disk exec: dd if=/dev/zero of=DD bs=8M count=10000 oflag=direct 10000+0 records in 10000+0 records out 83886080000 bytes (84 GB) copied, 126,03 s, 666 MB/s but if I remove "oflag=direct" option obtain about 80 MB/s. In read benchmark, results are similar: dd of=/dev/null if=DD bs=8M count=10000 iflag=direct 10000+0 records in 10000+0 records out 83886080000 bytes (84 GB) copied, 79,5918 s, 1,1 GB/s If remove iflag=direct obtain 150MB/s... I don't understand this huge differences, on other machines y don't have this behavior. Can I have some kernel parameter misconfigured? Thanks!

    Read the article

  • MySQL: Load database to memory

    - by Adam Matan
    Hi, Is there a way to load an entire MySQL database to the RAM, especially on en EC2 server? The database is quite small (~500 MegaBytes) I have enough memory Speed issues are crucial - the resulted queries are used to serve a dynamic webpage. Thanks, Adam

    Read the article

  • Does this prove a network bandwidth bottleneck?

    - by Yuji Tomita
    I've incorrectly assumed that my internal AB testing means my server can handle 1k concurrency @3k hits per second. My theory at at the moment is that the network is the bottleneck. The server can't send enough data fast enough. External testing from blitz.io at 1k concurrency shows my hits/s capping off at 180, with pages taking longer and longer to respond as the server is only able to return 180 per second. I've served a blank file from nginx and benched it: it scales 1:1 with concurrency. Now to rule out IO / memcached bottlenecks (nginx normally pulls from memcached), I serve up a static version of the cached page from the filesystem. The results are very similar to my original test; I'm capped at around 180 RPS. Splitting the HTML page in half gives me double the RPS, so it's definitely limited by the size of the page. If I internally ApacheBench from the local server, I get consistent results of around 4k RPS on both the Full Page and the Half Page, at high transfer rates. Transfer rate: 62586.14 [Kbytes/sec] received If I AB from an external server, I get around 180RPS - same as the blitz.io results. How do I know it's not intentional throttling? If I benchmark from multiple external servers, all results become poor which leads me to believe the problem is in MY servers outbound traffic, not a download speed issue with my benchmarking servers / blitz.io. So I'm back to my conclusion that my server can't send data fast enough. Am I right? Are there other ways to interpret this data? Is the solution/optimization to set up multiple servers + load balancing that can each serve 180 hits per second? I'm quite new to server optimization, so I'd appreciate any confirmation interpreting this data. Outbound traffic Here's more information about the outbound bandwidth: The network graph shows a maximum output of 16 Mb/s: 16 megabits per second. Doesn't sound like much at all. Due to a suggestion about throttling, I looked into this and found that linode has a 50mbps cap (which I'm not even close to hitting, apparently). I had it raised to 100mbps. Since linode caps my traffic, and I'm not even hitting it, does this mean that my server should indeed be capable of outputting up to 100mbps but is limited by some other internal bottleneck? I just don't understand how networks at this large of a scale work; can they literally send data as fast as they can read from the HDD? Is the network pipe that big? In conclusion 1: Based on the above, I'm thinking I can definitely raise my 180RPS by adding an nginx load balancer on top of a multi nginx server setup at exactly 180RPS per server behind the LB. 2: If linode has a 50/100mbit limit that I'm not hitting at all, there must be something I can do to hit that limit with my single server setup. If I can read / transmit data fast enough locally, and linode even bothers to have a 50mbit/100mbit cap, there must be an internal bottleneck that's not allowing me to hit those caps that I'm not sure how to detect. Correct? I realize the question is huge and vague now, but I'm not sure how to condense it. Any input is appreciated on any conclusion I've made.

    Read the article

  • Is it reasonable that a random disk seek & read costs ~16ms?

    - by fzhang
    I am frustrated about the latency of random reading from a non-ssd disk. Based on results from following test program, it speeds ~16 ms for a random read of just 512 bytes without help of os cache. I tried changing 512 to larger values, such as 25k, and the latency did not increase as much. I guess it is because the disk seek dominates the time. I understand that random reading is inherently slow, but just want to be sure that ~16ms is reasonable, even for non-ssd disk. #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> #include <sys/unistd.h> #include <fcntl.h> #include <limits.h> #include <stdio.h> #include <string.h> int main(int argc, char** argv) { int fd = open(argv[1], O_RDONLY); if (fd < 0) { fprintf(stderr, "Failed open %s\n", argv[1]); return -1; } const size_t count = 512; const off_t offset = 25990611 / 2; char buffer[count] = { '\0' }; struct timeval start_time; gettimeofday(&start_time, NULL); off_t ret = lseek(fd, offset, SEEK_SET); if (ret != offset) { perror("lseek error"); close(fd); return -1; } ret = read(fd, buffer, count); if (ret != count) { fprintf(stderr, "Failed reading all: %ld\n", ret); close(fd); return -1; } struct timeval end_time; gettimeofday(&end_time, NULL); printf("tv_sec: %ld, tv_usec: %ld\n", end_time.tv_sec - start_time.tv_sec, end_time.tv_usec - start_time.tv_usec); close(fd); return 0; }

    Read the article

< Previous Page | 194 195 196 197 198 199 200 201 202 203 204 205  | Next Page >