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• Samba Domain Controller corrupts Windows workstations profiles?

  - by MrZombie

  Oooooook, so here's my problem. I have a Mac OS X Server 10.5 to which Windows XP workstations are bound. I happened upon some errors and warnings in my log, from Userenv. Namely, error 1504, 1509. The warning complains that some setting on the share about offline caching. I found some guides to correct this if the problem was referring to a Windows server, but since those are Samba shares, the guide of course doesn't apply. Does anyone know what to do so that my profiles don't corrupt, and I still can use roaming profiles so that they're backed up by the server?

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• Brightness keeps changing in Windows 8.1 (on Macbook Pro Retina)

  - by gzak

  Before anyone gets too excited, it's not the "Adaptive Brightness" feature of the OS. I've already turned that off. Also it seems to have nothing to do with ambient light. It actually seems to do with the average "color" of the display. If I'm working in dark-themed Visual Studio, the brightness "pops" brighter. When I switch to the browser, it "pops" darker. So it's kind of adaptive brightness based on average pixel color (or something like that). What makes it rather annoying is that the brightness pops, rather than transitioning gradually. What is this feature, and how do I disable it (or at least make it smoother)?

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• New host, high load?

  - by dotancohen

  A few minutes ago I signed up at a new webhost. I have yet to move my sites over. Upon initial SSH connection, I checked the load and memory usage, they do seem rather higher than I would like: # uptime 12:06:51 up 71 days, 23:23, 1 user, load average: 9.02, 9.49, 9.45 # free total used free shared buffers cached Mem: 33014800 31927192 1087608 0 2384812 17729816 -/+ buffers/cache: 11812564 21202236 Swap: 16787916 8584 16779332 Is that a bit to packed? I'm only paying about $5 USD per month, so I don't expect <0.1 loads, but ~10 is worrisome. Is it not? Also, there is no /etc/issue file so I tried other methods to guess the OS: # uname -a Linux box358.bluehost.com 2.6.32-20120131.55.1.bh6.x86_64 #1 SMP Tue Jan 31 15:43:27 EST 2012 x86_64 x86_64 x86_64 GNU/Linux # which yum /usr/bin/yum # which apt-get # That looks like CentOS / RHEL 6.2 possibly?

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• What's a good Linux distro for an older PC?

  - by jdamae

  I'm new to Linux and I am interested in installing it on an older computer I have. I want to set a web server up, and install PHP and Perl on it. My PC is an older HP Pavilion a255c, with an Intel Pentium 4 processor and 512 MB of RAM. I will probably add some more memory later. This PC is more like a sandbox than anything, but I would like to get started quickly with the OS. Is there a particular flavor of Linux I would need to download because I have an old computer? I was thinking about Ubuntu, but I'm not sure what version to go with.

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• HP Pavilion dv6000 graphics issue

  - by Tony

  A few days ago my laptop seized up on me while I was playing a game. When I restarted the computer, it sent me back to 640x480 resolution with 16 colors (clearly a graphical issue). In device manager, it shows an error, stating "Windows has stopped this device because it has reported problems. (Code 43)" regarding the video card. Upon removing and re-installing the drivers using both Windows Update and my own searching through nvidia's site, it's given me zero results. For kicks, I ran my antivirus (you never know!) and registry cleaner to see if anything would turn up. The antivirus found nothing, but CCleaner found 27 registry errors all dealing with my video card. What could be the cause of this, and what course of action would you recommend in this situation? Thanks in advance for the help! OS: Windows 7 Professional GPU: nvidia GeForce 8400M GS

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• Internet speed showing high value but never felt that speed [closed]

  - by Kiran D Pillai

  I use Reliance Netconnect+ in my Toshiba Satellite laptop. My OS is Windows 7 Ultimate. I've seen speeds up to 1500 kbps when travelling and have an average speed of 400 kbps at my room premises. I'm sorry, I've never felt that much speed while browsing or downloading. Sometimes I think some other programs are also sharing the same network. It is just showing 200 or 500 kbps but I feel 25 or 50 kbps. Is there any way to prevent them? I use Google Chrome downloaded from Google site. Please suggest me some solutions.

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• MySql Data Loss - post mortem analysis - RackSpace Cloud Server

  - by marfarma

  After a recent 'emergency migration' of a RS cloud server, the mysql databases on our server snapshot image proved to be days out of date from the backup date. And yet files that were uploaded through the impacted webapp had been written to the file system. Related metadata that was written to the database was lost, but the files themselves were backed-up. Once I was able to manually access the mysql data files before the mysql server started (server was configured to start mysql on boot), I was able to see that the update time for ib_logfile1, ib_logfile0 and ibdata1 was days old. As with this poster, mysql data loss after server crash, it's as if some caching controller had told the OS / mysql server that it had committed data that was still in cache, and it was lost instead of flushed. I can't quite wrap my head around how the uploaded files got written but the database data did not. I would have thought that any cache would have flushed system wide, rather than process by process. Any suggestions as to how this might have happened?

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• Pivotal Announces JSR-352 Compliance for Spring Batch

  - by reza_rahman

  Pivotal, the company currently funding development of the popular Spring Framework, recently announced JSR 352 (aka Batch Applications for the Java Platform) compliance for the Spring Batch project. More specifically, Spring Batch targets JSR-352 Java SE runtime compatibility rather than Java EE runtime compatibility. If you are surprised that APIs included in Java EE can pass TCKs targeted for Java SE, you should not be. Many other Java EE APIs target compatibility in Java SE environments such as JMS and JPA. You can read about Spring Batch's support for JSR-352 here as well as the Spring configuration to get JSR-352 working in Spring (typically a very low level implementation concern intended to be completely transparent to most JSR-352 users). JSR 352 is one of the few very encouraging cases of major active contribution to the Java EE standard from the Spring development team (the other major effort being Rod Johnson's co-leadership of JSR 330 along with Bob Lee). While IBM's Christopher Vignola led the spec and contributed IBM's years of highly mission critical batch processing experience from products like WebSphere Compute Grid and z/OS batch, the Spring team provided major influences to the API in particular for the chunk processing, listeners, splits and operational interfaces. The GlassFish team's own Mahesh Kannan also contributed, in particular by implementing much of the Java EE integration work for the reference implementation. This was an excellent example of multilateral engineering collaboration through the standards process. For many complex reasons it is not too hard to find evidence of less than amicable interaction between the Spring ecosystem and the Java EE standard over the years if one cares to dig deep enough. In reality most developers see Spring and Java EE as two sides of the same server-side Java coin. At the core Spring and Java EE ecosystems have always shared deep undercurrents of common user bases, bi-directional flows of ideas and perhaps genuine if not begrudging mutual respect. We can all hope for continued strength for both ecosystems and graceful high notes of collaboration via efforts like JSR 352.

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• Moving files fails due to privileges but they seem to be OK

  - by joaoc

  I am trying to copy old files from an OS X 10.5.8 to a new external HD. When trying to copy a folder I get the message: The operation cannot be completed because you do not have sufficient privileges for some of the items. I've checked the privileges and they seem ok (read & write for me). What is curious is that the folder is created empty on the target drive and I can then copy the contents from inside the original folder to inside the new folder without changing anything else. This happens with several folders but not all and is making backup a pain. I have to figure out which folder broke the copy, copy its contents to the external disk and then select what hasn't been copied to copy (and eventually stop at some point and repeating the experience)

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• Forward Shibboleth Environment Variables to Tomcat via Apache

  - by Deepak Singh Rawat

  I am using Shibbolethv2.3 with Apache web server and Tomcat application server. I am using Apache as a reverse proxy using mod_proxy.so. I am not able to forward the Shibboleth environment variables from Apache to Tomcat. I am able to forward the attributes in the headers but as already mentioned in the wiki this approach is not safe. I have tried forwarding the environment variables by the following directive : SetEnv AJP_username ${username} then at the Java side I can access the attribute by : request.getAttribute("username"); The strange thing here is that, I get a different value instead of the one set by Shibboleth. I get the Windows account name as a result. If I use any other attribute name, I get a null value. I have searched a lot and have run out of options. Please guide me towards the right solution. My setup details : Shibboleth version : 2.3 OS : Windows XP SP3 Webserver : Apache 2.2 Application Server : Tomcat 6 Proxy module : mod_proxy.so

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• ext4 jbd2 journaling active even on empty filesystem

  - by Paul

  I have been having several issues with my ext4 filesystems that seem to be due to jbd2 journaling. I made a related post here and am rephrasing it with the hope that someone may be able to help. For a minimal example, I start with an empty 8gb USB stick and use gparted to create one ext4 partition. The command used by gparted when creating the ext4 file system is: mkfs.ext4 -j -O extent -L DataTraveler8gb /dev/sde1 I check the filesystem with gparted: e2fsck -f -y -v /dev/sde1 and I mount it: sudo mount /dev/sde1 /media/test The disk is empty, but the journaling is very active on this disk (/dev/sde1). The other disks are ext4 SSDs formatted similarly. A snapshot of iotop: % sudo iotop -oPa Total DISK READ: 0.00 B/s | Total DISK WRITE: 2027.21 K/s PID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 262 be/3 root 0.00 B 56.00 K 0.00 % 0.18 % [jbd2/sda1-8] 29069 be/3 root 0.00 B 0.00 B 0.00 % 0.16 % [jbd2/sde1-8] 891 be/3 root 0.00 B 4.00 K 0.00 % 0.03 % [jbd2/sdc1-8] What is jbd2 doing with /dev/sde1? If I follow the same steps with a larger 2Tb disk, iotop indicates this empty disk is constantly being written to by jbd2 at the rate of Mb/s as soon as I mount it. On the other disks, which have the OS and /home, I have tried to find if any files are being modified by processes to cause this behavior but couldn't find any. I also moved many of the disk intensive process to use a tmpfs. And used noatime. I have another non-SSD hard disk on this machine, /dev/sdb, that is also ext4 but was not formatted by gparted (given to me by a coworker). It does not appear in iotop. So I am assuming there an issue with gparted. Any suggestions are appreciated. Also any tips on how to modify existing partitions to fix the issue without having to start from scratch would be great. There are some posts related to jbd2 but they didn't help (eg. here).

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• How to add missing fonts to Adobe Illustrator?

  - by WilliamKF

  When opening an Adobe Acrobat PDF document on Mac OS X Lion to edit in Adobe Illustrator CS6, I got the message: The font Helvetica-Narrow-Bold is missing. Affected text will be displayed using a substitute font. The font QuickTypePi is missing. Affected text will be displayed using a substitute font. How can I provide the missing fonts so that no substitution occurs and upon return to Adobe Acrobat Pro X the original fonts will remain after any edits in Illustrator? Or, since the message talks about their display, will the font remain unchanged upon return to Adobe Acrobat?

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• Login loop in Snow Leopard

  - by hgpc

  I can't get out of a login loop of a particular admin user. After entering the password the login screen is shown again after about a minute. Other users work fine. It started happening after a simple reboot. Can you please help me? Thank you! Tried to no avail: Change the password Remove the password Repair disk (no errors) Boot in safe mode Reinstall Snow Leopard and updating to 10.6.6 Remove content of ~/Library/Caches Removed content of ~/Library/Preferences Replaced /etc/authorization with Install DVD copy The system.log mentions a crash report. I'm including both below. system.log Jan 8 02:43:30 loginwindow218: Login Window - Returned from Security Agent Jan 8 02:43:30 loginwindow218: USER_PROCESS: 218 console Jan 8 02:44:42 kernel[0]: Jan 8 02:44:43: --- last message repeated 1 time --- Jan 8 02:44:43 com.apple.launchd[1] (com.apple.loginwindow218): Job appears to have crashed: Bus error Jan 8 02:44:43 com.apple.UserEventAgent-LoginWindow223: ALF error: cannot find useragent 1102 Jan 8 02:44:43 com.apple.UserEventAgent-LoginWindow223: plugin.UserEventAgentFactory: called with typeID=FC86416D-6164-2070-726F-70735C216EC0 Jan 8 02:44:43 /System/Library/CoreServices/loginwindow.app/Contents/MacOS/loginwindow233: Login Window Application Started Jan 8 02:44:43 SecurityAgent228: CGSShutdownServerConnections: Detaching application from window server Jan 8 02:44:43 com.apple.ReportCrash.Root232: 2011-01-08 02:44:43.936 ReportCrash232:2903 Saved crash report for loginwindow218 version ??? (???) to /Library/Logs/DiagnosticReports/loginwindow_2011-01-08-024443_localhost.crash Jan 8 02:44:44 SecurityAgent228: MIG: server died: CGSReleaseShmem : Cannot release shared memory Jan 8 02:44:44 SecurityAgent228: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged. Jan 8 02:44:44 SecurityAgent228: CGSDisplayServerShutdown: Detaching display subsystem from window server Jan 8 02:44:44 SecurityAgent228: HIToolbox: received notification of WindowServer event port death. Jan 8 02:44:44 SecurityAgent228: port matched the WindowServer port created in BindCGSToRunLoop Jan 8 02:44:44 loginwindow233: Login Window Started Security Agent Jan 8 02:44:44 WindowServer234: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged. Jan 8 02:44:44 com.apple.WindowServer234: Sat Jan 8 02:44:44 .local WindowServer234 <Error>: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged. Jan 8 02:44:54 SecurityAgent243: NSSecureTextFieldCell detected a field editor ((null)) that is not a NSTextView subclass designed to work with the cell. Ignoring... Crash report Process: loginwindow 218 Path: /System/Library/CoreServices/loginwindow.app/Contents/MacOS/loginwindow Identifier: loginwindow Version: ??? (???) Code Type: X86-64 (Native) Parent Process: launchd [1] Date/Time: 2011-01-08 02:44:42.748 +0100 OS Version: Mac OS X 10.6.6 (10J567) Report Version: 6 Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: 0x000000000000000a, 0x000000010075b000 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.apple.security 0x00007fff801c6e8b Security::ReadSection::at(unsigned int) const + 25 1 com.apple.security 0x00007fff801c632f Security::DbVersion::open() + 123 2 com.apple.security 0x00007fff801c5e41 Security::DbVersion::DbVersion(Security::AppleDatabase const&, Security::RefPointer<Security::AtomicBufferedFile> const&) + 179 3 com.apple.security 0x00007fff801c594e Security::DbModifier::getDbVersion(bool) + 330 4 com.apple.security 0x00007fff801c57f5 Security::DbModifier::openDatabase() + 33 5 com.apple.security 0x00007fff801c5439 Security::Database::_dbOpen(Security::DatabaseSession&, unsigned int, Security::AccessCredentials const*, void const*) + 221 6 com.apple.security 0x00007fff801c4841 Security::DatabaseManager::dbOpen(Security::DatabaseSession&, Security::DbName const&, unsigned int, Security::AccessCredentials const*, void const*) + 77 7 com.apple.security 0x00007fff801c4723 Security::DatabaseSession::DbOpen(char const*, cssm_net_address const*, unsigned int, Security::AccessCredentials const*, void const*, long&) + 285 8 com.apple.security 0x00007fff801d8414 cssm_DbOpen(long, char const*, cssm_net_address const*, unsigned int, cssm_access_credentials const*, void const*, long*) + 108 9 com.apple.security 0x00007fff801d7fba CSSM_DL_DbOpen + 106 10 com.apple.security 0x00007fff801d62f6 Security::CssmClient::DbImpl::open() + 162 11 com.apple.security 0x00007fff801d8977 SSDatabaseImpl::open(Security::DLDbIdentifier const&) + 53 12 com.apple.security 0x00007fff801d8715 SSDLSession::DbOpen(char const*, cssm_net_address const*, unsigned int, Security::AccessCredentials const*, void const*, long&) + 263 13 com.apple.security 0x00007fff801d8414 cssm_DbOpen(long, char const*, cssm_net_address const*, unsigned int, cssm_access_credentials const*, void const*, long*) + 108 14 com.apple.security 0x00007fff801d7fba CSSM_DL_DbOpen + 106 15 com.apple.security 0x00007fff801d62f6 Security::CssmClient::DbImpl::open() + 162 16 com.apple.security 0x00007fff802fa786 Security::CssmClient::DbImpl::unlock(cssm_data const&) + 28 17 com.apple.security 0x00007fff80275b5d Security::KeychainCore::KeychainImpl::unlock(Security::CssmData const&) + 89 18 com.apple.security 0x00007fff80291a06 Security::KeychainCore::StorageManager::login(unsigned int, void const*, unsigned int, void const*) + 3336 19 com.apple.security 0x00007fff802854d3 SecKeychainLogin + 91 20 com.apple.loginwindow 0x000000010000dfc5 0x100000000 + 57285 21 com.apple.loginwindow 0x000000010000cfb4 0x100000000 + 53172 22 com.apple.Foundation 0x00007fff8721e44f __NSThreadPerformPerform + 219 23 com.apple.CoreFoundation 0x00007fff82627401 __CFRunLoopDoSources0 + 1361 24 com.apple.CoreFoundation 0x00007fff826255f9 __CFRunLoopRun + 873 25 com.apple.CoreFoundation 0x00007fff82624dbf CFRunLoopRunSpecific + 575 26 com.apple.HIToolbox 0x00007fff8444493a RunCurrentEventLoopInMode + 333 27 com.apple.HIToolbox 0x00007fff8444473f ReceiveNextEventCommon + 310 28 com.apple.HIToolbox 0x00007fff844445f8 BlockUntilNextEventMatchingListInMode + 59 29 com.apple.AppKit 0x00007fff80b01e64 _DPSNextEvent + 718 30 com.apple.AppKit 0x00007fff80b017a9 -NSApplication nextEventMatchingMask:untilDate:inMode:dequeue: + 155 31 com.apple.AppKit 0x00007fff80ac748b -NSApplication run + 395 32 com.apple.loginwindow 0x0000000100004b16 0x100000000 + 19222 33 com.apple.loginwindow 0x0000000100004580 0x100000000 + 17792 Thread 1: Dispatch queue: com.apple.libdispatch-manager 0 libSystem.B.dylib 0x00007fff8755216a kevent + 10 1 libSystem.B.dylib 0x00007fff8755403d _dispatch_mgr_invoke + 154 2 libSystem.B.dylib 0x00007fff87553d14 _dispatch_queue_invoke + 185 3 libSystem.B.dylib 0x00007fff8755383e _dispatch_worker_thread2 + 252 4 libSystem.B.dylib 0x00007fff87553168 _pthread_wqthread + 353 5 libSystem.B.dylib 0x00007fff87553005 start_wqthread + 13 Thread 0 crashed with X86 Thread State (64-bit): rax: 0x000000010075b000 rbx: 0x00007fff5fbfd990 rcx: 0x00007fff875439da rdx: 0x0000000000000000 rdi: 0x00007fff5fbfd990 rsi: 0x0000000000000000 rbp: 0x00007fff5fbfd5d0 rsp: 0x00007fff5fbfd5d0 r8: 0x0000000000000007 r9: 0x0000000000000000 r10: 0x00007fff8753beda r11: 0x0000000000000202 r12: 0x0000000100133e78 r13: 0x00007fff5fbfda50 r14: 0x00007fff5fbfda50 r15: 0x00007fff5fbfdaa0 rip: 0x00007fff801c6e8b rfl: 0x0000000000010287 cr2: 0x000000010075b000

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• How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk

  - by The Geek

  We’ve covered loads of different anti-virus, Linux, and other boot disks that help you repair or recover your system, but why limit yourself to just one? Here’s how to combine your favorite repair disks together to create the ultimate repair toolkit for broken Windows systems—all on a single flash drive. The ones we’ve covered already? Here’s a quick list of all the ways you can recover your system with a rescue disk: How to Use the Avira Rescue CD to Clean Your Infected PC How to Use the BitDefender Rescue CD to Clean Your Infected PC How to Use the Kaspersky Rescue Disk to Clean Your Infected PC Change or Reset Windows Password from a Ubuntu Live CD The 10 Cleverest Ways to Use Linux to Fix Your Windows PC Change Your Forgotten Windows Password with the Linux System Rescue CD Use Ubuntu Live CD to Backup Files from Your Dead Windows Computer If you need to clean up an infected system, we’d absolutely recommend the BitDefender CD, since it’s auto-updating. Best bet? Create your ultimate boot disk with as many of the different utilities as your flash drive can hold Latest Features How-To Geek ETC How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 The 50 Best How-To Geek Windows Articles of 2010 The 20 Best How-To Geek Explainer Topics for 2010 How to Disable Caps Lock Key in Windows 7 or Vista How to Use the Avira Rescue CD to Clean Your Infected PC Luigi Installs Any OS on Google’s Cr-48 Notebook DIY iPad Stylus Offers Pen-Based Interaction on the Cheap Serene Blue Ubuntu Wallpaper for Your Desktop Enjoy Old School Style Video Game Fun with Chicken Invaders Hide the Twitter “Litter” in Twitter’s Sidebar Area (Chrome and Iron) Public Domain Day: Reflections on Copyright and the Importance of Public Domain

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• Aptana Under linux

  - by fatnjazzy

  Hey, I downloaded the Aptanastudio 2.0 and unzipped it in the desktop. Im trying to run Aptana studio 2.0 under OpenSuse 11 and i get the following error... Any idea y? Thanks JVM terminated. Exit code=-1 -Xms40m -Xmx384m -Djava.awt.headless=true -XX:MaxPermSize=256m -Djava.class.path=/home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher_1.0.200.v20090520.jar -os linux -ws gtk -arch x86 -showsplash -launcher /home/avi/Desktop/Aptana Studio 2.0/AptanaStudio -name AptanaStudio --launcher.library /home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher.gtk.linux.x86_1.0.200.v20090520/eclipse_1206.so -startup /home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher_1.0.200.v20090520.jar -application com.aptana.ide.desktop.integration.Application -vm /usr/lib/jvm/java-1.6.0-openjdk-1.6.0/jre/bin/../lib/i386/client/libjvm.so -vmargs -Xms40m -Xmx384m -Djava.awt.headless=true -XX:MaxPermSize=256m -Djava.class.path=/home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher_1.0.200.v20090520.jar

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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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• Redirect example.com to www.example.com VPS & Apache2

  - by Thomas Buckley

  I have a VPS and a domain name registered with the provider. When I enter www.example.com my site is displayed correctly, but entering example.com does not work. I am able to ping www.example.com. I added the following line to my apache2 default vhosts file: ServerName example.com ServerAlias www.example.com But this did not work. The VPS is a Debian5 OS. Any ideas? Note: There is no option via a provided control panel to add this, it's a basic package I purchased I know this post answers it but there are no extra comments and I'd like to know if it's the best way: way to redirect page to www using virtual host configuration in sites-available for apache2? Thanks

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• Tools to test multicast routing

  - by Zoredache

  I am looking for a good simple tool that runs on a standard OS (Windows or Linux) that I can used to test that multicast is being passed properly by a router. I have been asked by a client to enable multicast routing on a Linux box acting as their router since their phone system requires multicast to for a few features. Since I am not physically near the client I don't really have the ability to experiment with the various methods for setting up multicast routing on Linux. I can setup a router at my desk that is identical to what is deployed on their network, but I don't know of any good simple tools that I can use to generate or listen for multicast traffic. The one mulicast tool I have found is mcast.exe tool which is part of the Windows 2000/2003 resource kit. From what I have read online it seems that mcast.exe does not work across a router, and only works on the local network, so that doesn't seem to be useful for me to test multicast routing. So what do tool(s) do you use to test that multicast routing is properly setup?

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• WebLogic Server 11g with java based node manager stdout/stderr log path configuration.

  - by Mircea Vutcovici

  Hi, How I can configure the path where the stdout logs are written by the WebLogic server? I've read about -Dweblogic.log.RedirectStdoutToServerLogEnabled=true, but this redirects only part of the output. For example if I will run a thread dump, the output will remain in the original log file. I think it should be an option in nodemanager/startup.properties file. WebLogic version is 10.3.2.0 and I am using a java based node manager. OS is RHEL 5. Thank you, Mircea

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• network timeout how to analyse problem

  - by elhombre

  In the last three month I was experiencing that my internet connection started to get very slow and websites had long time to load. The first thing I made was an ping to www.google.com which showed that I was loosing pakets. Here some of the results: 64 bytes from 74.125.39.103: icmp_seq=2909 ttl=53 time=48.222 ms Request timeout for icmp_seq 2910 Request timeout for icmp_seq 2911 64 bytes from 74.125.39.103: icmp_seq=2912 ttl=53 time=44.372 ms Days later I had to reset my router because it wasn't able to establish a correct network connection. It was after the reset when things worked again for some days. But later the same network timeouts started to happen again. I would like to know how I can analyze the problem to get to the source which is causing this timeouts. Which steps do you take to circle in this Problem? My Network Laptop - Wireless Router modem - ISP EDIT: I am on a Mac OS X 10.6

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• Audio doesn't work on Windows XP guest (WS 7.0)

  - by Mads

  I can't get audio to work with on a Windows XP guest running on VMware Workstation 7.0 and Ubuntu 9.10 host. Windows fails to produce any audio output and the Windows device manager says the Multimedia Audio Controller is not working properly. Audio is working fine in the host OS. When I open Multimedia Audio Controller properties it says: Device status: The drivers for this device are not installed (Code 28) If I try to reinstall the driver I get the following error message: Cannot Install this Hardware There was a problem installing this hardware: Multimedia Audio Controller An Error occurred during the installation of the device Driver is not intended for this platform Has anyone else experienced this problem?

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• How do I remove a repository of yum

  - by sunil

  When I search for a package in yum(centos 6), it tries to search in a repro named 'c6-media' And it gives a bunch of errors as follows file:///media/CentOS/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/CentOS/repodata/repomd.xml Trying other mirror. file:///media/cdrecorder/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/cdrecorder/repodata/repomd.xml Trying other mirror. file:///media/cdrom/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/cdrom/repodata/repomd.xml Trying other mirror. Error: Cannot retrieve repository metadata (repomd.xml) for repository: c6-media. Please verify its path and try again Obviously the error seems to say that yum is trying to search for the CD/DVD which installed the OS. I do not have it now. All I want to do now is to delete this repository from yum. I went to the package manager graphical tool and removed this from the sources. Seems yum and the graphical tool do not use the same config. This is just my guess.

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• Keyboard automatically disconnects and reconnects

  - by Algorithms

  The problem i am facing is the keyboard (USB) automatically disconnects when there is a fluctuation in the power supply to the speaker. The speaker and the pc both draw power from a apc ups. The fluctuation occurs because the speaker plug is not tightly connected to the ups power outlet. It is okay for normal work, but a accidental jerk causes the fluctuation. However after some amount of time (usually within 5 seconds) the keyboard automatically reconnects and windows plays the sound of hardware connected. This problem will also occur if I manually take out the speaker power cable from the ups power outlet. My question is whether the problem I am facing is due to electrical issues, or due to software problems. PC config: OS : Windows 7 Ultimate UPS : APC 600 VA PSU : Corsair TX 650 Speaker : Realtek

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• Snow Leopard Compatible Drivers for Moschip MCS7720 USB-to-Serial Controller

  - by Kristopher Johnson

  We are using Cables Unlimited USB-2925 USB-to-Dual-DB9 serial cables, which use the Moschip MCS7720 controller. We have downloaded the newest driver from http://www.moschip.com/mcs7720.php, but that driver was last updated in 2005. It does not seem to be working with Macs running OS X 10.6 Snow Leopard. We have sent emails to the support addresses for both Cables Unlimited and Moschip. Cables Unlimited says they are checking with Moschip. No responses from Moschip yet. Does anyone know of any updates for this driver, or are there any ways to get the driver to work with Snow Leopard?

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• Flash Player in Windows 7 X64 problems

  - by Flupkear

  I'm having a lot of problems with flash player in my win 7 X64 laptop, in YouTube the videos are completely black, you can only hear the sound and in Vimeo the videos are played well in normal size but completely black in fullscreen. Also some days ago YouTube played normal size videos but with controls not visible. I'm sure that the problem isn't the browser since this happen in Chrome, Firefox and IE 8. My laptop is a Dell XPS L501X, the flash version is 10,2,152,26 and the OS is Windows 7 Home Premium with SP1. I'll appreciate any help.

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