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  • CPU and Data alignment

    - by MS
    Dear All, Pardon me if you feel this has been answered numerous times, but I need answers to the following queries! Why data has to be aligned (on 4 byte/ 8 byte/ 2 byte boundaries)? Here my doubt is when the CPU has address lines Ax Ax-1 Ax-2 ... A2 A1 A0 then it is quite possible to address the memory locations sequentially. So why there is the need to align the data at specific boundaries? How to find the alignment requirements when I am compiling my code and generating the executatble? If for e.g the data alignment is 4 byte boundary, does that mean each consecutive byte is located at modulo 4 offsets? My doubt is if data is 4 byte aligned does that mean that if a byte is at 1004 then the next byte is at 1008 (or at 1005)? Your thoughts are much welcome. Thanks in advance! /MS

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  • C# Confusing Results from Performance Test

    - by aip.cd.aish
    I am currently working on an image processing application. The application captures images from a webcam and then does some processing on it. The app needs to be real time responsive (ideally < 50ms to process each request). I have been doing some timing tests on the code I have and I found something very interesting (see below). clearLog(); log("Log cleared"); camera.QueryFrame(); camera.QueryFrame(); log("Camera buffer cleared"); Sensor s = t.val; log("Sx: " + S.X + " Sy: " + S.Y); Image<Bgr, Byte> cameraImage = camera.QueryFrame(); log("Camera output acuired for processing"); Each time the log is called the time since the beginning of the processing is displayed. Here is my log output: [3 ms]Log cleared [41 ms]Camera buffer cleared [41 ms]Sx: 589 Sy: 414 [112 ms]Camera output acuired for processing The timings are computed using a StopWatch from System.Diagonostics. QUESTION 1 I find this slightly interesting, since when the same method is called twice it executes in ~40ms and when it is called once the next time it took longer (~70ms). Assigning the value can't really be taking that long right? QUESTION 2 Also the timing for each step recorded above varies from time to time. The values for some steps are sometimes as low as 0ms and sometimes as high as 100ms. Though most of the numbers seem to be relatively consistent. I guess this may be because the CPU was used by some other process in the mean time? (If this is for some other reason, please let me know) Is there some way to ensure that when this function runs, it gets the highest priority? So that the speed test results will be consistently low (in terms of time). EDIT I change the code to remove the two blank query frames from above, so the code is now: clearLog(); log("Log cleared"); Sensor s = t.val; log("Sx: " + S.X + " Sy: " + S.Y); Image<Bgr, Byte> cameraImage = camera.QueryFrame(); log("Camera output acuired for processing"); The timing results are now: [2 ms]Log cleared [3 ms]Sx: 589 Sy: 414 [5 ms]Camera output acuired for processing The next steps now take longer (sometimes, the next step jumps to after 20-30ms, while the next step was previously almost instantaneous). I am guessing this is due to the CPU scheduling. Is there someway I can ensure the CPU does not get scheduled to do something else while it is running through this code?

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  • Why is numpy's einsum faster than numpy's built in functions?

    - by Ophion
    Lets start with three arrays of dtype=np.double. Timings are performed on a intel CPU using numpy 1.7.1 compiled with icc and linked to intel's mkl. A AMD cpu with numpy 1.6.1 compiled with gcc without mkl was also used to verify the timings. Please note the timings scale nearly linearly with system size and are not due to the small overhead incurred in the numpy functions if statements these difference will show up in microseconds not milliseconds: arr_1D=np.arange(500,dtype=np.double) large_arr_1D=np.arange(100000,dtype=np.double) arr_2D=np.arange(500**2,dtype=np.double).reshape(500,500) arr_3D=np.arange(500**3,dtype=np.double).reshape(500,500,500) First lets look at the np.sum function: np.all(np.sum(arr_3D)==np.einsum('ijk->',arr_3D)) True %timeit np.sum(arr_3D) 10 loops, best of 3: 142 ms per loop %timeit np.einsum('ijk->', arr_3D) 10 loops, best of 3: 70.2 ms per loop Powers: np.allclose(arr_3D*arr_3D*arr_3D,np.einsum('ijk,ijk,ijk->ijk',arr_3D,arr_3D,arr_3D)) True %timeit arr_3D*arr_3D*arr_3D 1 loops, best of 3: 1.32 s per loop %timeit np.einsum('ijk,ijk,ijk->ijk', arr_3D, arr_3D, arr_3D) 1 loops, best of 3: 694 ms per loop Outer product: np.all(np.outer(arr_1D,arr_1D)==np.einsum('i,k->ik',arr_1D,arr_1D)) True %timeit np.outer(arr_1D, arr_1D) 1000 loops, best of 3: 411 us per loop %timeit np.einsum('i,k->ik', arr_1D, arr_1D) 1000 loops, best of 3: 245 us per loop All of the above are twice as fast with np.einsum. These should be apples to apples comparisons as everything is specifically of dtype=np.double. I would expect the speed up in an operation like this: np.allclose(np.sum(arr_2D*arr_3D),np.einsum('ij,oij->',arr_2D,arr_3D)) True %timeit np.sum(arr_2D*arr_3D) 1 loops, best of 3: 813 ms per loop %timeit np.einsum('ij,oij->', arr_2D, arr_3D) 10 loops, best of 3: 85.1 ms per loop Einsum seems to be at least twice as fast for np.inner, np.outer, np.kron, and np.sum regardless of axes selection. The primary exception being np.dot as it calls DGEMM from a BLAS library. So why is np.einsum faster that other numpy functions that are equivalent? The DGEMM case for completeness: np.allclose(np.dot(arr_2D,arr_2D),np.einsum('ij,jk',arr_2D,arr_2D)) True %timeit np.einsum('ij,jk',arr_2D,arr_2D) 10 loops, best of 3: 56.1 ms per loop %timeit np.dot(arr_2D,arr_2D) 100 loops, best of 3: 5.17 ms per loop The leading theory is from @sebergs comment that np.einsum can make use of SSE2, but numpy's ufuncs will not until numpy 1.8 (see the change log). I believe this is the correct answer, but have not been able to confirm it. Some limited proof can be found by changing the dtype of input array and observing speed difference and the fact that not everyone observes the same trends in timings.

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  • Is there any way that an export-to-Excel function can be scalable?

    - by MusiGenesis
    Summary: ASP.Net website with a couple hundred users. Data is exported to Excel files which can be relatively large (~5 MB). In the pilot phase (just a few users), we are already seeing occasional errors on the server in the exporting method. Here's the stack trace: System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. --- System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown. at System.IO.MemoryStream.set_Capacity(Int32 value) at System.IO.MemoryStream.EnsureCapacity(Int32 value) at System.IO.MemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Packaging.TrackingMemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Packaging.SparseMemoryStream.WriteAndCollapseBlocks(Byte[ ] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Packaging.SparseMemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Packaging.CompressEmulationStream.Write(Byte[] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Packaging.CompressStream.Write(Byte[] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Zip.ProgressiveCrcCalculatingStream.Write(Byte[] buffer, Int32 offset, Int32 count) at MS.Internal.IO.Zip.ZipIOModeEnforcingStream.Write(Byte[] buffer, Int32 offset, Int32 count) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.IO.StreamWriter.Write(String value) at System.Xml.XmlTextEncoder.Write(String text) at System.Xml.XmlTextWriter.WriteString(String text) at System.Xml.XmlText.WriteTo(XmlWriter w) at System.Xml.XmlAttribute.WriteContentTo(XmlWriter w) at System.Xml.XmlAttribute.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteContentTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteContentTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteContentTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlDocument.WriteContentTo(XmlWriter xw) at System.Xml.XmlDocument.WriteTo(XmlWriter w) at System.Xml.XmlDocument.Save(Stream outStream) at OfficeOpenXml.ExcelWorksheet.Save() in C:\temp\XXXXXXXXXX\ExcelPackage\ExcelWorksheet.cs:line 605 at OfficeOpenXml.ExcelWorkbook.Save() in C:\temp\XXXXXXXXXX\ExcelPackage\ExcelWorkbook.cs:line 439 at OfficeOpenXml.ExcelPackage.Save() in C:\temp\XXXXXXXXXX\ExcelPackage\ExcelPackage.cs:line 348 at Framework.Exporting.Business.ExcelExport.BuildReport(HttpContext context) at WebUserControl.BtnXLS_Click(Object sender, EventArgs e) in C:\TEMP\XXXXXXXXXX\XXXXXXXXXX\OneList\UserControls\TicketReportExporter. ascx.cs:line 108 at System.Web.UI.WebControls.Button.OnClick(EventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.Rai sePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace --- at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.XXXXXXXXXXX_aspx.ProcessRequest(HttpContext context) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\XXXX\cdf32a52\d1a5eabd\App_Web_enxdwlks.1.cs:line 0 at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpAppli cation.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Even aside from this particular problem, in general exporting to Excel requires the instantiation of huge Excel objects on the server for each request, which I've always assumed to mean disqualifies Excel for "serious" work on a highly-loaded server. Is there any general way to export to Excel in a "light-weight" manner? Would simply streaming the data into a CSV file work for this?

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  • Exception showing a erroneous web page in a WPF frame

    - by H4mm3rHead
    I have a small application where i need to navigate to an url, I use this method to get the Frame: public override System.Windows.UIElement GetPage(System.Windows.UIElement container) { XmlDocument doc = new XmlDocument(); doc.Load(Location); string webSiteUrl = doc.SelectSingleNode("website").InnerText; Frame newFrame = new Frame(); if (!webSiteUrl.StartsWith("http://")) { webSiteUrl = "http://" + webSiteUrl; } newFrame.Source = new Uri(webSiteUrl); return newFrame; } My problem is now that the page im trying to show generates a error (or so i think), when i load the page in a browser it never fully loads, keeps saying "loading1 element" in the load bar and the green progress line (IE 8) keeps showing. When i attach my debugger i get this error: System.ArgumentException was unhandled Message="Parameter and value pair is not valid. Expected form is parameter=value." Source="WindowsBase" StackTrace: at MS.Internal.ContentType.ParseParameterAndValue(String parameterAndValue) at MS.Internal.ContentType..ctor(String contentType) at MS.Internal.WpfWebRequestHelper.GetContentType(WebResponse response) at System.Windows.Navigation.NavigationService.GetObjectFromResponse(WebRequest request, WebResponse response, Uri destinationUri, Object navState) at System.Windows.Navigation.NavigationService.HandleWebResponse(IAsyncResult ar) at System.Windows.Navigation.NavigationService.<>c__DisplayClassc.<HandleWebResponseOnRightDispatcher>b__8(Object unused) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) ved System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.TranslateAndDispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Application.RunInternal(Window window) at GreenWebPlayerWPF.App.Main() i C:\Development\Hvarregaard\GWDS\GreenWeb\GreenWebPlayerWPF\obj\Debug\App.g.cs:linje 0 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: Anyone? Or any way to capture it and respond to it, tried a try/catch around my code, but its not caught - seems something deep inside the guts of the CLR is failing.

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  • Silent application installation script

    - by Achu
    I use the following script to install application from the server: ECHO OFF IF EXIST "C:\SCRIPTS\drvsw01.cmd" GOTO :L1 C: LABEL System_Drive CD\ MD SCRIPTS COPY U:\Scripts\*.* C:\SCRIPTS\ install.exe -i silent -DLICENSE_ACCEPTED=true -f response_file ECHO "SCRIPTS FOLDER INSTALLATION SUCCESSFUL" :L1 ECHO "JAVA INSTALLATION" U:\Softwares\Java_Run_Time\jre-6u26-windows-i586.exe ECHO "JAVA INSTALLATION SUCCESSFUL" ECHO "OFFICE SOFTWARE INSTALLATION" ECHO "MS OFFICE INSTALLATION" U:\Softwares\Office_2007\setup.exe ECHO "MS-OFFICE INSTALLATION SUCCESSFUL" U:\Softwares\SaveAsPDFandXPS.exe ECHO "MS-OFFICE PDF%XPS Add in INSTALLATION SUCCESSFUL" ECHO "NETWORK SCAN GEAR INSTALLATION" U:\Softwares\ScanGear\english\DISK1\setup.exe ECHO "NETWORK SCAN GEAR INSTALLATION SUCCESSFUL" ECHO "7ZIP INSTALLATION" U:\Softwares\7ZIP\7z457.EXE E CHO "7ZIP INSTALLATION SUCCESSFUL" ECHO "IFAN VIEW INSTALLATION" U:\Softwares\IrfanView_4.5\iview425_setup.exe ECHO "IFAN VIEW INSTALLATION SUCCESSFUL" U:\Softwares\IrfanView\irfanview_plugins_425_setup.exe ECHO "IFAN VIEW PLUGINS INSTALLATION SUCCESSFUL" U:\Softwares\Firefox4\Firefox4.exe ECHO "FIREFOX INSTALLATION SUCCESSFUL" ECHO "FIREFOX PLUGIN INSTALLATION" U:\Softwares\Flash_Player_10\install_flash_player.EXE U:\Softwares\Flash_Player_10\install_flash_player_10_active_x.exe ECHO "FIREFOX INSTALLATION SUCCESSFUL" ECHO "ACROBAT READER 10 INSTALLATION" U:\Softwares\Adobe_Acrobat_Reader_10\AdbeRdr10.exe ECHO "ACROBAT 10 Installation SuccESSFUL" ECHO "INSTALLATION CD burner WINDOWS XP" U:\Softwares\CDburnerxpsetup.exe ECHO "Installation of CD burner Successful" ECHO "INSTALLATION IE8 for WINDOWS XP" U:\SOFTWARE\IE8\IE8-WindowsXP-x86-ENU.exe ECHO "INSTALLATION IE8 SUCCESSFUL" ECHO "THE USER ACCOUNT WOULD BE DELETED" NET USER USER /DELETE ECHO "USER ACCOUNT DELETE SUCCESSFUL" echo %ERRORLEVEL% Now, i want to make this script installing everything silently except MS-Office. Ms-Office b/c i have to customize installing only word, excel & powerpoint. How can i make this script silent? or are there a nice script for this? Thanks,

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  • remote telnet and email

    - by Mustafa Ismail Mustafa
    This issue has been occupying my work for the last few days and I will be understating when I say its driven me up the blasted walls. Essentially, I can ping and tracert the domain jnrcs.org and the subdomains mail.jnrcs.org and mail.jordanredcrescent.org. All three mentioned point to ip address 212.38.147.97. About 4 days ago, when we registered the domain "jnrcs.org" suddenly all external connection to the mail server from outside was lost. Not just mail, but other http based port-forwarded or natted services (such as camera surveillance and pbx services). I tried good old telnet (I'm a linux user) and I get the following output: telnet> o mail.jnrcs.org 25 Trying 212.38.147.97... telnet: Unable to connect to remote host: No route to host telnet> Tracert gives me: traceroute to mail.jnrcs.org (212.38.147.97), 30 hops max, 60 byte packets 1 192.168.1.2 (192.168.1.2) 0.869 ms 0.944 ms * 2 * * * 3 * * * 4 * * * 5 * * * 6 * 212.38.128.118 (212.38.128.118) 33.875 ms 39.187 ms 7 * * * 8 * * * 9 * * * 10 * * * 11 * * 212.38.147.97 (212.38.147.97) 67.621 ms I am stumped. Other friends from all around the world can telnet no problem. What could have possibly happened to make telnet/smtp/pop/imap/http access stop? Please bear in mind I'm primarily a developer but I [am under the delusion] that I can carry my weight in IT administration :) TIA

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  • Mpd as pppoe server with authorisation by freeradius2

    - by Korjavin Ivan
    I install freeradius2, add to raddb/users: test Cleartext-Password := "test1" Service-Type = Framed-User, Framed-Protocol = PPP, Framed-IP-Address = 10.36.0.2, Framed-IP-Netmask = 255.255.255.0, start radiusd, and check auth: radtest test test1 127.0.0.1 1002 testing123 Sending Access-Request of id 199 to 127.0.0.1 port 1812 User-Name = "test" User-Password = "test1" NAS-IP-Address = 127.0.0.1 NAS-Port = 1002 Message-Authenticator = 0x00000000000000000000000000000000 rad_recv: Access-Accept packet from host 127.0.0.1 port 1812, id=199, length=44 Service-Type = Framed-User Framed-Protocol = PPP Framed-IP-Address = 10.36.0.2 Framed-IP-Netmask = 255.255.255.0 Works fine. Next step. Add to mpd.conf: radius: set auth disable internal set auth max-logins 1 CI set auth enable radius-auth set radius timeout 90 set radius retries 2 set radius server 127.0.0.1 testing123 1812 1813 set radius me 127.0.0.1 create link template L pppoe set link action bundle B set link max-children 1000 set link no multilink set link no shortseq set link no pap chap-md5 chap-msv1 chap-msv2 set link enable chap set pppoe acname Internet load radius create link template em1 L set pppoe iface em1 set link enable incoming And trying to connect, auth failed, here is mpd log: mpd: [em1-2] LCP: auth: peer wants nothing, I want CHAP mpd: [em1-2] CHAP: sending CHALLENGE #1 len: 21 mpd: [em1-2] LCP: LayerUp mpd: [em1-2] CHAP: rec'd RESPONSE #1 len: 58 mpd: [em1-2] Name: "test" mpd: [em1-2] AUTH: Trying RADIUS mpd: [em1-2] RADIUS: Authenticating user 'test' mpd: [em1-2] RADIUS: Rec'd RAD_ACCESS_REJECT for user 'test' mpd: [em1-2] AUTH: RADIUS returned: failed mpd: [em1-2] AUTH: ran out of backends mpd: [em1-2] CHAP: Auth return status: failed mpd: [em1-2] CHAP: Reply message: ^AE=691 R=1 mpd: [em1-2] CHAP: sending FAILURE #1 len: 14 mpd: [em1-2] LCP: authorization failed Then i start freeradius as radiusd -fX, and get this log: rad_recv: Access-Request packet from host 127.0.0.1 port 46400, id=223, length=282 NAS-Identifier = "rubin.svyaz-nt.ru" NAS-IP-Address = 127.0.0.1 Message-Authenticator = 0x14d36639bed8074ec2988118125367ea Acct-Session-Id = "815965-em1-2" NAS-Port = 2 NAS-Port-Type = Ethernet Service-Type = Framed-User Framed-Protocol = PPP Calling-Station-Id = "00e05290b3e3 / 00:e0:52:90:b3:e3 / em1" NAS-Port-Id = "em1" Vendor-12341-Attr-12 = 0x656d312d32 Tunnel-Medium-Type:0 = IEEE-802 Tunnel-Client-Endpoint:0 = "00:e0:52:90:b3:e3" User-Name = "test" MS-CHAP-Challenge = 0xbb1e68d5bbc30f228725a133877de83e MS-CHAP2-Response = 0x010088746ae65b68e435e9d045ad6f9569b60000000000000000b56991b4f20704cb6c68e5982eec5e98a7f4b470c109c1b9 # Executing section authorize from file /usr/local/etc/raddb/sites-enabled/default +- entering group authorize {...} ++[preprocess] returns ok ++[chap] returns noop [mschap] Found MS-CHAP attributes. Setting 'Auth-Type = mschap' ++[mschap] returns ok [eap] No EAP-Message, not doing EAP ++[eap] returns noop [files] users: Matched entry DEFAULT at line 172 ++[files] returns ok Found Auth-Type = MSCHAP # Executing group from file /usr/local/etc/raddb/sites-enabled/default +- entering group MS-CHAP {...} [mschap] No Cleartext-Password configured. Cannot create LM-Password. [mschap] No Cleartext-Password configured. Cannot create NT-Password. [mschap] Creating challenge hash with username: test [mschap] Client is using MS-CHAPv2 for test, we need NT-Password [mschap] FAILED: No NT/LM-Password. Cannot perform authentication. [mschap] FAILED: MS-CHAP2-Response is incorrect ++[mschap] returns reject Failed to authenticate the user. Login incorrect: [test] (from client localhost port 2 cli 00e05290b3e3 / 00:e0:52:90:b3:e3 / em1) Using Post-Auth-Type REJECT # Executing group from file /usr/local/etc/raddb/sites-enabled/default +- entering group REJECT {...} [attr_filter.access_reject] expand: %{User-Name} -> test attr_filter: Matched entry DEFAULT at line 11 ++[attr_filter.access_reject] returns updated Delaying reject of request 2 for 1 seconds Going to the next request Waking up in 0.9 seconds. Sending delayed reject for request 2 Sending Access-Reject of id 223 to 127.0.0.1 port 46400 MS-CHAP-Error = "\001E=691 R=1" Why i have error "[mschap] No Cleartext-Password configured. Cannot create LM-Password." ? I define cleartext-password in users. I check raddb/sites-enabled/default authorize { chap mschap eap { ok = return } files } looks ok for me. Whats wrong with mpd/chap/radius ?

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  • Parralelization in Microsoft SQL Server 2008 R2

    - by stan31337
    We have a specific accounting and production software, called 1C, which uses single user connection to the MS SQL 2008 R2 database. And there are about 500 users connecting to 1C server to perform their tasks. 1C and SQL 2008 are on separate servers. How to configure MS SQL 2008 R2 to effectively use parallelization in this configuration? We have 24 cores, and only one is loaded at 100% at MS SQL 2008 R2 server. We have already configured MS SQL max parallelizm from this MSDN article: http://msdn.microsoft.com/en-us/library/ms181007(v=sql.105).aspx Thank you!

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  • What does the number after 7-zip's -m switch mean?

    - by AndreKR
    7-zip has a command line switch to set the compression method, -m followed by a number, e.g. -m0=LZMA. What does the number (0 in the example) mean? Different numbers produce slightly different compression results and performance: time 7z -m0=LZMA -mx=9 -ms=on -mmt=off real 0m2.292s user 0m2.190s sys 0m0.080s time 7z -m1=LZMA -mx=9 -ms=on -mmt=off real 0m2.405s user 0m3.240s sys 0m0.070s time 7z -m0=LZMA -mx=9 -ms=on -mmt=on real 0m1.038s user 0m1.920s sys 0m0.150s time 7z -m1=LZMA -mx=9 -ms=on -mmt=on real 0m1.187s user 0m2.800s sys 0m0.130s

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  • No External Network Access Through Ubuntu VPN

    - by trobrock
    I have setup pptpd as my VPN server on Ubuntu Server 9.04, I am able to connect to the VPN from the client and can access the server's local network, but I am unable to connect to the external network via the VPN. If I login to the server via SSH: $ ping google.com PING google.com (74.125.67.100) 56(84) bytes of data. 64 bytes from gw-in-f100.google.com (74.125.67.100): icmp_seq=1 ttl=49 time=65.9 ms 64 bytes from gw-in-f100.google.com (74.125.67.100): icmp_seq=2 ttl=49 time=63.2 ms 64 bytes from gw-in-f100.google.com (74.125.67.100): icmp_seq=3 ttl=49 time=63.9 ms 64 bytes from gw-in-f100.google.com (74.125.67.100): icmp_seq=4 ttl=49 time=66.0 ms If I connect to the VPN and ping locally: $ ping google.com ping: cannot resolve google.com: Unknown host I have a feeling it is some routing issue on the server but I am unsure.

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  • Retrieving a virtual box vdh that has been deleted from within Virtual box itself

    - by WillNZ
    I had a MS Virtual machine that I imported to virtual box to see how it worked. I decided that in this case MS Virtual machine worked just as good so removed the virtual machine from Virtual Box. In the process I accidently removed/deleted the vhd file that MS Virtual machine uses. Can I get this back from somewhere within virtual box or the recycle bin or do I have to use a undelete utlilty?

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  • Linq2SQL vs NHibernate performance (have I gone mad?)

    - by HeavyWave
    I have written the following tests to compare performance of Linq2SQL and NHibernate and I find results to be somewhat strange. Mappings are straight forward and identical for both. Both are running against a live DB. Although I'm not deleting Campaigns in case of Linq, but that shouldn't affect performance by more than 10 ms. Linq: [Test] public void Test1000ReadsWritesToAgentStateLinqPrecompiled() { Stopwatch sw = new Stopwatch(); Stopwatch swIn = new Stopwatch(); sw.Start(); for (int i = 0; i < 1000; i++) { swIn.Reset(); swIn.Start(); ReadWriteAndDeleteAgentStateWithLinqPrecompiled(); swIn.Stop(); Console.WriteLine("Run ReadWriteAndDeleteAgentState: " + swIn.ElapsedMilliseconds + " ms"); } sw.Stop(); Console.WriteLine("Total Time: " + sw.ElapsedMilliseconds + " ms"); Console.WriteLine("Average time to execute queries: " + sw.ElapsedMilliseconds / 1000 + " ms"); } private static readonly Func<AgentDesktop3DataContext, int, EntityModel.CampaignDetail> GetCampaignById = CompiledQuery.Compile<AgentDesktop3DataContext, int, EntityModel.CampaignDetail>( (ctx, sessionId) => (from cd in ctx.CampaignDetails join a in ctx.AgentCampaigns on cd.CampaignDetailId equals a.CampaignDetailId where a.AgentStateId == sessionId select cd).FirstOrDefault()); private void ReadWriteAndDeleteAgentStateWithLinqPrecompiled() { int id = 0; using (var ctx = new AgentDesktop3DataContext()) { EntityModel.AgentState agentState = new EntityModel.AgentState(); var campaign = new EntityModel.CampaignDetail { CampaignName = "Test" }; var campaignDisposition = new EntityModel.CampaignDisposition { Code = "123" }; campaignDisposition.Description = "abc"; campaign.CampaignDispositions.Add(campaignDisposition); agentState.CallState = 3; campaign.AgentCampaigns.Add(new AgentCampaign { AgentState = agentState }); ctx.CampaignDetails.InsertOnSubmit(campaign); ctx.AgentStates.InsertOnSubmit(agentState); ctx.SubmitChanges(); id = agentState.AgentStateId; } using (var ctx = new AgentDesktop3DataContext()) { var dbAgentState = ctx.GetAgentStateById(id); Assert.IsNotNull(dbAgentState); Assert.AreEqual(dbAgentState.CallState, 3); var campaignDetails = GetCampaignById(ctx, id); Assert.AreEqual(campaignDetails.CampaignDispositions[0].Description, "abc"); } using (var ctx = new AgentDesktop3DataContext()) { ctx.DeleteSessionById(id); } } NHibernate (the loop is the same): private void ReadWriteAndDeleteAgentState() { var id = WriteAgentState().Id; StartNewTransaction(); var dbAgentState = agentStateRepository.Get(id); Assert.IsNotNull(dbAgentState); Assert.AreEqual(dbAgentState.CallState, 3); Assert.AreEqual(dbAgentState.Campaigns[0].Dispositions[0].Description, "abc"); var campaignId = dbAgentState.Campaigns[0].Id; agentStateRepository.Delete(dbAgentState); NHibernateSession.Current.Transaction.Commit(); Cleanup(campaignId); NHibernateSession.Current.BeginTransaction(); } Results: NHibernate: Total Time: 9469 ms Average time to execute 13 queries: 9 ms Linq: Total Time: 127200 ms Average time to execute 13 queries: 127 ms Linq lost by 13.5 times! Event with precompiled queries (both read queries are precompiled). This can't be right, although I expected NHibernate to be faster, this is just too big of a difference, considering mappings are identical and NHibernate actually executes more queries against the DB.

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  • Windows 8 ignores more specific route

    - by Lander
    OS: Windows 8 I have a cabled NIC (connected to router with ip 192.168.1.0) and a WIFI NIC (connected to a router with ip 192.168.1.1) . I want all traffic to go through the cabled NIC, except the 192.168.1.0/8 range should use the wifi-nic. This was working fine in Windows 7, without any manual configuration. In Windows 8 however, it's not. My routing table: =========================================================================== Interface List 14...f2 7b cb 13 e7 f0 ......Microsoft Wi-Fi Direct Virtual Adapter 13...b8 ac 6f 54 d2 5c ......Realtek PCIe FE Family Controller 12...f0 7b cb 13 e7 f0 ......Dell Wireless 1397 WLAN Mini-Card 1...........................Software Loopback Interface 1 15...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter 16...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.198 30 0.0.0.0 0.0.0.0 192.168.0.1 192.168.0.233 20 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 192.168.0.0 255.255.255.0 On-link 192.168.0.233 276 192.168.0.233 255.255.255.255 On-link 192.168.0.233 276 192.168.0.255 255.255.255.255 On-link 192.168.0.233 276 192.168.1.0 255.255.255.0 192.168.1.1 192.168.1.198 31 192.168.1.198 255.255.255.255 On-link 192.168.1.198 286 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 192.168.0.233 276 224.0.0.0 240.0.0.0 On-link 192.168.1.198 286 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 192.168.0.233 276 255.255.255.255 255.255.255.255 On-link 192.168.1.198 286 =========================================================================== Persistent Routes: None I added the rule for 192.168.1.0. I would think Windows should use this rule for the IP 192.168.1.1 because it's more specific than the default-route. However it's not: C:\Windows\system32>tracert 192.168.1.1 Tracing route to 192.168.1.1 over a maximum of 30 hops 1 58 ms 4 ms 4 ms 192.168.0.1 2 68 ms 12 ms 11 ms ^C So... What do I do wrong? And how can I make Windows use the wireless NIC for 192.168.1.0/8

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  • mysql.sock problem on Mac OS X, all Zend products

    - by Michael Stelly
    Hi folks. I posted this on the Zend forum, but I'm hoping I can get a speedier reply here. I've tried every solution provided on this forum with no luck. When I restart mysql, everything appears ok. sudo /usr/local/zend/bin/zendctl.sh restart Password: /usr/local/zend/bin/apachectl stop [OK] /usr/local/zend/bin/apachectl start [OK] Stopping Zend Server GUI [Lighttpd] [OK] spawn-fcgi: child spawned successfully: PID: 7943 Starting Zend Server GUI [Lighttpd] [OK] Stopping Java bridge [OK] Starting Java bridge [OK] Shutting down MySQL . SUCCESS! Starting MySQL . SUCCESS! Pinging locahost is also OK and resolve dns to IP. ping localhost PING localhost (127.0.0.1): 56 data bytes 64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.048 ms 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.064 ms 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.066 ms 64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.076 ms 64 bytes from 127.0.0.1: icmp_seq=4 ttl=64 time=0.064 ms But when I attempt to access the local url for my app, I get the dreaded: Message: SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2). This is a show-stopper for me. I appreciate any assistance. Thank you.

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  • I am unable to connect to my netbook from any machine on my network until the netbook has pinged it

    - by Samuel Husky
    I have a rather strange issue with my netbook on my local network. When trying to connect to it in any way from a remote system it does not appear to find it. However if I get the netbook to ping the machine trying to connect it mystically appears to work. Below is the ping test from my main PC to the netbook. C:\Users\Sam>ping 192.168.8.102 Pinging 192.168.8.102 with 32 bytes of data: Reply from 192.168.8.100: Destination host unreachable. Reply from 192.168.8.100: Destination host unreachable. Reply from 192.168.8.100: Destination host unreachable. Reply from 192.168.8.100: Destination host unreachable. Ping statistics for 192.168.8.102: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Now a ping from the netbook to my main PC sam@malamute ~ $ ping 192.168.8.100 PING 192.168.8.100 (192.168.8.100) 56(84) bytes of data. 64 bytes from 192.168.8.100: icmp_req=1 ttl=128 time=2.46 ms 64 bytes from 192.168.8.100: icmp_req=2 ttl=128 time=0.835 ms 64 bytes from 192.168.8.100: icmp_req=3 ttl=128 time=1.60 ms 64 bytes from 192.168.8.100: icmp_req=4 ttl=128 time=1.32 ms 64 bytes from 192.168.8.100: icmp_req=5 ttl=128 time=1.34 ms ^C --- 192.168.8.100 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4004ms rtt min/avg/max/mdev = 0.835/1.514/2.460/0.536 ms And the same ping again from the main PC after the netbook has made a connection to it C:\Users\Sam>ping 192.168.8.102 Pinging 192.168.8.102 with 32 bytes of data: Reply from 192.168.8.102: bytes=32 time=1ms TTL=64 Reply from 192.168.8.102: bytes=32 time=1ms TTL=64 Reply from 192.168.8.102: bytes=32 time=1ms TTL=64 Reply from 192.168.8.102: bytes=32 time=1ms TTL=64 Ping statistics for 192.168.8.102: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 1ms, Maximum = 1ms, Average = 1ms The netbook is running Gentoo and is currently connected via wireless. My main PC is running Windows 7 however I get the same result no matter what PC I use on this network. Please see this example from a CentOS machine on the same network [root@tiger ~]# ping 192.168.8.102 PING 192.168.8.102 (192.168.8.102) 56(84) bytes of data. From 192.168.8.200 icmp_seq=2 Destination Host Unreachable From 192.168.8.200 icmp_seq=3 Destination Host Unreachable From 192.168.8.200 icmp_seq=4 Destination Host Unreachable --- 192.168.8.102 ping statistics --- 6 packets transmitted, 0 received, +3 errors, 100% packet loss, time 5000ms , pipe 3 If you need any more information or require logs or config files please let me know and any assistance is greatly appreciated. Additional info: No responses on TCP dump from the netbook. Same result when booting into Ubuntu from a USB key. No issue when using a wired Ethernet connection.

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  • Cisco: unable to negotiate IP using IPCP with Windows server

    - by lnk
    I am connecting to Windows server using PPP (for vpn), I establish connection but server does not respond me for my address requests: *Mar 23 00:40:06.055: Vi1 MS-CHAP-V2: I CHALLENGE id 0 len 25 from "MSDC" *Mar 23 00:40:06.063: Vi1 MS CHAP V2: Using hostname from interface CHAP *Mar 23 00:40:06.063: Vi1 MS CHAP V2: Using password from interface CHAP *Mar 23 00:40:06.067: Vi1 MS-CHAP-V2: O RESPONSE id 0 len 69 from "XXX" *Mar 23 00:40:06.087: Vi1 PPP: I pkt type 0xC223, datagramsize 50 link[ppp] *Mar 23 00:40:06.087: Vi1 MS-CHAP-V2: I SUCCESS id 0 len 46 msg is "S=XXX" *Mar 23 00:40:06.087: Vi1 MS CHAP V2 No Password found for : XXX *Mar 23 00:40:06.091: Vi1 MS CHAP V2 Check AuthenticatorResponse Success for : XXX *Mar 23 00:40:06.091: Vi1 IPCP: O CONFREQ [Closed] id 1 len 20 *Mar 23 00:40:06.091: Vi1 IPCP: VSO OUI 0x00000C kind 1 (0x000A00000C0100000000) *Mar 23 00:40:06.091: Vi1 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 23 00:40:07.091: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access1, changed state to up *Mar 23 00:40:07.091: Vi1 LCP: O ECHOREQ [Open] id 1 len 12 magic 0x194CAFCF *Mar 23 00:40:07.103: Vi1 LCP-FS: I ECHOREP [Open] id 1 len 12 magic 0x361B62E5 *Mar 23 00:40:07.103: Vi1 LCP-FS: Received id 1, sent id 1, line up *Mar 23 00:40:08.083: Vi1 IPCP: TIMEout: State REQsent *Mar 23 00:40:08.083: Vi1 IPCP: O CONFREQ [REQsent] id 2 len 20 *Mar 23 00:40:08.083: Vi1 IPCP: VSO OUI 0x00000C kind 1 (0x000A00000C0100000000) *Mar 23 00:40:08.083: Vi1 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 23 00:40:10.099: Vi1 IPCP: TIMEout: State REQsent *Mar 23 00:40:10.099: Vi1 IPCP: O CONFREQ [REQsent] id 3 len 20 *Mar 23 00:40:10.099: Vi1 IPCP: VSO OUI 0x00000C kind 1 (0x000A00000C0100000000) *Mar 23 00:40:10.099: Vi1 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 23 00:40:12.115: Vi1 IPCP: TIMEout: State REQsent *Mar 23 00:40:12.115: Vi1 IPCP: O CONFREQ [REQsent] id 4 len 20 *Mar 23 00:40:12.115: Vi1 IPCP: VSO OUI 0x00000C kind 1 (0x000A00000C0100000000) *Mar 23 00:40:12.115: Vi1 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 23 00:40:12.211: Vi1 LCP: O ECHOREQ [Open] id 2 len 12 magic 0x194CAFCF *Mar 23 00:40:12.219: Vi1 LCP-FS: I ECHOREP [Open] id 2 len 12 magic 0x361B62E5 *Mar 23 00:40:12.219: Vi1 LCP-FS: Received id 2, sent id 2, line up *Mar 23 00:40:14.131: Vi1 IPCP: TIMEout: State REQsent *Mar 23 00:40:14.131: Vi1 IPCP: O CONFREQ [REQsent] id 5 len 20 *Mar 23 00:40:14.131: Vi1 IPCP: VSO OUI 0x00000C kind 1 (0x000A00000C0100000000) *Mar 23 00:40:14.131: Vi1 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 23 00:40:16.147: Vi1 IPCP: TIMEout: State REQsent *Mar 23 00:40:16.147: Vi1 IPCP: O CONFREQ [REQsent] id 6 len 20 *Mar 23 00:40:16.147: Vi1 IPCP: VSO OUI 0x00000C kind 1 (0x000A00000C0100000000) *Mar 23 00:40:16.147: Vi1 IPCP: Address 0.0.0.0 (0x030600000000) *Mar 23 00:40:17.331: Vi1 LCP: O ECHOREQ [Open] id 3 len 12 magic 0x194CAFCF *Mar 23 00:40:17.343: Vi1 LCP-FS: I ECHOREP [Open] id 3 len 12 magic 0x361B62E5 *Mar 23 00:40:17.343: Vi1 LCP-FS: Received id 3, sent id 3, line up You see: My router asks for address, but only keepalives are on line. But the same server works with windows client!! ! version 12.4 no service pad service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption service internal ! hostname Router ! boot-start-marker boot-end-marker ! ! no aaa new-model ! resource policy ! ip subnet-zero ! ! ip cef vpdn enable ! vpdn-group pptp request-dialin protocol pptp pool-member 1 initiate-to ip XXXX ! ! ! ! ! ! ! bridge irb ! ! interface ATM0 no ip address shutdown no atm ilmi-keepalive dsl operating-mode auto ! interface FastEthernet0 ! interface FastEthernet1 ! interface FastEthernet2 ! interface FastEthernet3 ! interface Dot11Radio0 no ip address shutdown speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0 54.0 station-role root ! interface Vlan1 no ip address bridge-group 1 ! interface Dialer0 ip address negotiated encapsulation ppp dialer pool 1 dialer idle-timeout 0 dialer string XXX dialer persistent dialer vpdn dialer-group 1 keepalive 5 3 no cdp enable ppp authentication ms-chap-v2 optional ppp eap refuse ppp chap hostname XXX ppp chap password 0 XXX ppp ipcp mask request ppp ipcp ignore-map ppp ipcp address accept ! interface BVI1 mac-address XXX.XXX.XXX ip address dhcp ! ip classless ip route 172.0.0.0 255.0.0.0 Dialer0 ! no ip http server no ip http secure-server ! dialer-list 1 protocol ip permit ! control-plane ! bridge 1 protocol vlan-bridge bridge 1 route ip ! line con 0 no modem enable line aux 0 line vty 0 4 login ! scheduler max-task-time 5000 end

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  • Windows Server 2008 R2 backup includes volume with MSSQL data

    - by J F
    I'm using wbadmin to schedule image backup every night on a Windows Server 2008 R2 Standard server. Ever since installing MS-SQL 2008 Express R2, wbadmin wants to also backup the volume where the MS-SQL data files are located (L:). I'm using -allCritical to make sure bare metal restore will work. command-line: wbadmin start backup -backupTarget:\\myserver\backup$\myserver\%DATE% -include:C: -allCritical -quiet I don't want to do this, because I'm backing up MS-SQL manually elsewhere. It worked just fine only taking C: before I installed MS-SQL.

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  • Where do vendors publish internal transfer rates of HDDs?

    - by red888
    So I've started to dig into storage fundamentals and found that in order to calculate the IOPS of a HDD you need to know the internal transfer rate of the drive (time it takes data to move from the platters to internal disk's cache). I went on newegg and even a few vendor sites and could not find this info published for any HDDs. Is it sometimes called something else? Take this link to a seagate HDD for instance. Nowhere do I see "internal transfer rate", but I do see something called "Sustained Data Rate OD"- is that the same thing? Just so you know where I'm getting this info (Book: "Information Storage and Management Storing, Managing..."): Consider an example with the following specifications provided for a disk: The average seek time is 5 ms in a random I/O environment; therefore, T = 5 ms. Disk rotation speed of 15,000 revolutions per minute or 250 revolutions per second — from which rotational latency (L) can be determined, which is one-half of the time taken for a full rotation or L = (0.5/250 rps expressed in ms). 40 MB/s internal data transfer rate, from which the internal transfer time (X) is derived based on the block size of the I/O — for example, an I/O with a block size of 32 KB; therefore X = 32 KB/40 MB. Consequently, the time taken by the I/O controller to serve an I/O of block size 32 KB is (TS) = 5 ms + (0.5/250) + 32 KB/40 MB = 7.8 ms. Therefore, the maximum number of I/Os serviced per second or IOPS is (1/TS) = 1/(7.8 × 10^-3) = 128 IOPS.

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  • How do I analyze an Apache Bench result?

    - by Alan Hoffmeister
    I need some help with analyzing a log from Apache Bench: Benchmarking texteli.com (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Completed 600 requests Completed 700 requests Completed 800 requests Completed 900 requests Completed 1000 requests Finished 1000 requests Server Software: Server Hostname: texteli.com Server Port: 80 Document Path: /4f84b59c557eb79321000dfa Document Length: 13400 bytes Concurrency Level: 200 Time taken for tests: 37.030 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 13524000 bytes HTML transferred: 13400000 bytes Requests per second: 27.01 [#/sec] (mean) Time per request: 7406.024 [ms] (mean) Time per request: 37.030 [ms] (mean, across all concurrent requests) Transfer rate: 356.66 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 27 37 19.5 34 319 Processing: 80 6273 1673.7 6907 8987 Waiting: 47 3436 2085.2 3345 8856 Total: 115 6310 1675.8 6940 9022 Percentage of the requests served within a certain time (ms) 50% 6940 66% 6968 75% 6988 80% 7007 90% 7025 95% 7078 98% 8410 99% 8876 100% 9022 (longest request) What this results can tell me? Isn't 27 rps too slow?

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  • Why "scope link" ipv6 address can be pinged via interfaces which they are not active on

    - by olagu
    [root@2_01 ~]# /sbin/ip -6 addr show pubeth0 inet6 2001:1::6/64 scope global inet6 2001:1::1/64 scope global inet6 fe80::20c:29ff:fe69:f9e8/64 scope link [root@v2_01 ~]# /sbin/ip -6 addr show pubeth1 inet6 fe80::20c:29ff:fe69:f906/64 scope link [root@2_01 ~]# ping6 fe80::20c:29ff:fe69:f9e8%pubeth1 PING fe80::20c:29ff:fe69:f9e8%pubeth1(fe80::20c:29ff:fe69:f9e8) 56 data bytes 64 bytes from fe80::20c:29ff:fe69:f9e8: icmp_seq=1 ttl=64 time=0.259 ms --- fe80::20c:29ff:fe69:f9e8%pubeth1 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 286ms rtt min/avg/max/mdev = 0.259/0.259/0.259/0.000 ms [root@2_01 ~]# ping6 fe80::20c:29ff:fe69:f9e8%pubeth0 PING fe80::20c:29ff:fe69:f9e8%pubeth0(fe80::20c:29ff:fe69:f9e8) 56 data bytes 64 bytes from fe80::20c:29ff:fe69:f9e8: icmp_seq=1 ttl=64 time=0.057 ms --- fe80::20c:29ff:fe69:f9e8%pubeth0 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 390ms rtt min/avg/max/mdev = 0.057/0.057/0.057/0.000 ms Why can I ping6 "fe80::20c:29ff:fe69:f9e8" via pubeth1?

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  • guvcview recording video and audio out of synchronisation in Ubuntu 10.10

    - by SIJAR
    I finally got Guvcview, a great software for Logitech webcam and it does all the stuff that one wants out of it. But I'm not satisfy with the video recording, video and audio out of synchronisation also video seems to be in slow motion. Please help so that I can tweak in and get a good video recording with the webcam. Below is the log of Guvcview ------------------------------------------------------------------------------- guvcview 1.4.1 video_device: /dev/video0 vid_sleep: 0 cap_meth: 1 resolution: 640 x 480 windowsize: 1024 x 715 vert pane: 578 spin behavior: 0 mode: mjpg fps: 1/25 Display Fps: 0 bpp: 0 hwaccel: 1 avi_format: 4 sound: 1 sound Device: 4 sound samp rate: 0 sound Channels: 0 Sound delay: 0 nanosec Sound Format: 85 Pan Step: 2 degrees Tilt Step: 2 degrees Video Filter Flags: 0 image inc: 0 profile(default):/home/sijar/default.gpfl starting portaudio... bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) Cannot connect to server socket err = No such file or directory Cannot connect to server socket jack server is not running or cannot be started language catalog= dir:/usr/share/locale type:UTF-8 lang:en_US.utf8 cat:guvcview.mo mjpg: setting format to 1196444237 capture method = 1 video device: /dev/video0 libv4lconvert: warning more framesizes then I can handle! libv4lconvert: warning more framesizes then I can handle! /dev/video0 - device 1 libv4lconvert: warning more framesizes then I can handle! libv4lconvert: warning more framesizes then I can handle! Init. UVC Camera (046d:0825) (location: usb-0000:00:1d.7-5) { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 176 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 432, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 544, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 640, height = 360 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, ... repeats a couple of times ... vid:046d pid:0825 driver:uvcvideo Adding control for Pan (relative) UVCIOC_CTRL_ADD - Error: Operation not permitted checking format: 1196444237 VIDIOC_G_COMP:: Invalid argument compression control not supported fps is set to 1/25 drawing controls control[0]: 0x980900 Brightness, 0:255:1, default 128 control[0]: 0x980901 Contrast, 0:255:1, default 32 control[0]: 0x980902 Saturation, 0:255:1, default 32 control[0]: 0x98090c White Balance Temperature, Auto, 0:1:1, default 1 control[0]: 0x980913 Gain, 0:255:1, default 0 control[0]: 0x980918 Power Line Frequency, 0:2:1, default 2 control[0]: 0x98091a White Balance Temperature, 0:10000:10, default 4000 control[0]: 0x98091b Sharpness, 0:255:1, default 24 control[0]: 0x98091c Backlight Compensation, 0:1:1, default 1 control[0]: 0x9a0901 Exposure, Auto, 0:3:1, default 3 control[0]: 0x9a0902 Exposure (Absolute), 1:10000:1, default 166 control[0]: 0x9a0903 Exposure, Auto Priority, 0:1:1, default 0 resolutions of format(2) = 19 frame rates of 1º resolution=6 Def. Res: 0 numb. fps:6 --------------------------------------- device #0 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 (hw:0,0) Host API = ALSA Max inputs = 2, Max outputs = 2 Def. low input latency = 0.012 Def. low output latency = 0.012 Def. high input latency = 0.046 Def. high output latency = 0.046 Def. sample rate = 44100.00 --------------------------------------- device #1 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - MIC ADC (hw:0,1) Host API = ALSA Max inputs = 2, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #2 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - MIC2 ADC (hw:0,2) Host API = ALSA Max inputs = 2, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #3 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - ADC2 (hw:0,3) Host API = ALSA Max inputs = 2, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #4 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - IEC958 (hw:0,4) Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.011 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #5 Name = USB Device 0x46d:0x825: USB Audio (hw:1,0) Host API = ALSA Max inputs = 1, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #6 Name = front Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.012 Def. high input latency = -1.000 Def. high output latency = 0.046 Def. sample rate = 44100.00 --------------------------------------- device #7 Name = iec958 Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.011 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #8 Name = spdif Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.011 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #9 Name = pulse Host API = ALSA Max inputs = 32, Max outputs = 32 Def. low input latency = 0.012 Def. low output latency = 0.012 Def. high input latency = 0.046 Def. high output latency = 0.046 Def. sample rate = 44100.00 --------------------------------------- device #10 Name = dmix Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.043 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #11 [ Default Input, Default Output ] Name = default Host API = ALSA Max inputs = 32, Max outputs = 32 Def. low input latency = 0.012 Def. low output latency = 0.012 Def. high input latency = 0.046 Def. high output latency = 0.046 Def. sample rate = 44100.00 ---------------------------------------------- SampleRate:0 Channels:0 Video driver: x11 A window manager is available VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_CTRL for user class controls control(0x0098091a) "White Balance Temperature" failed to set (error -1) VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_EXT_CTRLS on single controls for class: 0x009a0000 control(0x009a0902) "Exposure (Absolute)" failed to set (error -1) VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_CTRL for user class controls control(0x0098091a) "White Balance Temperature" failed to set (error -1) VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_EXT_CTRLS on single controls for class: 0x009a0000 control(0x009a0902) "Exposure (Absolute)" failed to set (error -1) Cap Video toggled: 1 (/home/sijar/Videos/Webcam) 25371756K bytes free on a total of 39908968K (used: 36 %) treshold=51200K using audio codec: 0x0055 Audio frame size is 1152 samples for selected codec IO thread started...OK [libx264 @ 0x8cbd8b0]using cpu capabilities: MMX2 SSE2 Cache64 [libx264 @ 0x8cbd8b0]profile Baseline, level 3.0 [libx264 @ 0x8cbd8b0]non-strictly-monotonic PTS shift sound by -9 ms shift sound by -9 ms shift sound by -9 ms AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... AUDIO: droping audio data (/home/sijar/Videos/Webcam) 25371748K bytes free on a total of 39908968K (used: 36 %) treshold=51200K AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... Cap Video toggled: 0 Shuting Down IO Thread AUDIO: droping audio data stop= 4426644744000 start=4416533023000 VIDEO: 146 frames in 10111.000000 ms = 14.439719 fps Stoping audio stream Closing audio stream... close avi Last message repeated 145 times [libx264 @ 0x8cbd8b0]frame I:2 Avg QP:14.10 size: 24492 [libx264 @ 0x8cbd8b0]frame P:103 Avg QP:16.06 size: 20715 [libx264 @ 0x8cbd8b0]mb I I16..4: 48.4% 0.0% 51.6% [libx264 @ 0x8cbd8b0]mb P I16..4: 57.5% 0.0% 0.0% P16..4: 40.2% 0.0% 0.0% 0.0% 0.0% skip: 2.3% [libx264 @ 0x8cbd8b0]final ratefactor: 62.05 [libx264 @ 0x8cbd8b0]coded y,uvDC,uvAC intra: 79.7% 92.2% 68.4% inter: 62.4% 87.5% 48.0% [libx264 @ 0x8cbd8b0]i16 v,h,dc,p: 23% 17% 41% 19% [libx264 @ 0x8cbd8b0]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 30% 24% 26% 2% 5% 3% 3% 3% 4% [libx264 @ 0x8cbd8b0]i8c dc,h,v,p: 53% 20% 23% 4% [libx264 @ 0x8cbd8b0]ref P L0: 63.0% 37.0% [libx264 @ 0x8cbd8b0]kb/s:-0.00 total frames encoded: 0 total audio frames encoded: 0 IO thread finished...OK IO Thread finished enabling controls Cap Video toggled: 1 (/home/sijar/Videos/Webcam) 25379744K bytes free on a total of 39908968K (used: 36 %) treshold=51200K using audio codec: 0x0055 Audio frame size is 1152 samples for selected codec IO thread started...OK [libx264 @ 0x8cfba20]using cpu capabilities: MMX2 SSE2 Cache64 [libx264 @ 0x8cfba20]profile Baseline, level 3.0 [libx264 @ 0x8cfba20]non-strictly-monotonic PTS shift sound by -236 ms shift sound by -236 ms shift sound by -236 ms (/home/sijar/Videos/Webcam) 25377044K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25373408K bytes free on a total of 39908968K (used: 36 %) treshold=51200K AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... (/home/sijar/Videos/Webcam) 25370696K bytes free on a total of 39908968K (used: 36 %) treshold=51200K AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... (/home/sijar/Videos/Webcam) 25367680K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25364052K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25360312K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25356628K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25352908K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25349316K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25345552K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25341828K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25338092K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25334412K bytes free on a total of 39908968K (used: 36 %) treshold=51200K Cap Video toggled: 0 Shuting Down IO Thread stop= 4708817235000 start=4578624714000 VIDEO: 1604 frames in 130192.000000 ms = 12.320265 fps Stoping audio stream Closing audio stream... close avi Last message repeated 1603 times [libx264 @ 0x8cfba20]frame I:16 Avg QP:14.78 size: 42627 [libx264 @ 0x8cfba20]frame P:1547 Avg QP:16.44 size: 28599 [libx264 @ 0x8cfba20]mb I I16..4: 21.6% 0.0% 78.4% [libx264 @ 0x8cfba20]mb P I16..4: 28.1% 0.0% 0.0% P16..4: 70.5% 0.0% 0.0% 0.0% 0.0% skip: 1.4% [libx264 @ 0x8cfba20]final ratefactor: 88.17 [libx264 @ 0x8cfba20]coded y,uvDC,uvAC intra: 74.4% 95.8% 83.2% inter: 75.2% 94.6% 69.2% [libx264 @ 0x8cfba20]i16 v,h,dc,p: 27% 17% 40% 16% [libx264 @ 0x8cfba20]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 25% 21% 3% 6% 4% 5% 4% 7% [libx264 @ 0x8cfba20]i8c dc,h,v,p: 61% 18% 18% 4% [libx264 @ 0x8cfba20]ref P L0: 64.0% 36.0% [libx264 @ 0x8cfba20]kb/s:-0.00 total frames encoded: 0 total audio frames encoded: 0 IO thread finished...OK IO Thread finished enabling controls Shuting Down Thread Thread terminated... cleaning Thread allocations: 100% SDL Quit Video Thread finished write /home/sijar/.guvcviewrc OK free audio mutex closed v4l2 strutures free controls free controls - vidState cleaned allocations - 100% Closing portaudio ...OK Closing GTK... OK

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  • IASA South East Florida Chapter February Meeting Report

    - by Rainer Habermann
    IASA South East Florida Chapter – February Meeting The topic for our February chapter meeting was Legal Issues in IT. Ms. Kennedy, Intellectual Property Attorney with an active litigation, trademark and copyright practice, presented: How Google, Wal-Mart & Apple Make their Millions – The Secret Ingredient: Intellectual Property This topic initiated great interest and the meeting room at Microsoft Ft. Lauderdale filled up to the last seat. Most Architects, Engineers, and MBA’s are not aware about Intellectual Property, Basic Patent, Trademark, or legal issues related to the web. After clarifying the basic definitions, Ms. Kennedy explained in detail how intellectual property issues could make or break a company. Members had the opportunity at the end of the presentation to ask questions, discuss legal problems, and several members shared their experiences related to Intellectual Property and other IT related issues. If you want to protect your ideas and intellectual property, you have to be aware of the implications and need to take the right steps in order to protect them. All Chapter Members agreed that it was an outstanding and lively presentation. Ms. Kennedy presented high quality content and made participants aware of legal IT issues. In the name of all chapter members, thank you Ms. Kennedy for taking the time for this amazing presentation and to Quent Herschelman for hosting the meeting. Rainer Habermann President IASA South East Florida Chapter

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  • Table Variables: an empirical approach.

    - by Phil Factor
    It isn’t entirely a pleasant experience to publish an article only to have it described on Twitter as ‘Horrible’, and to have it criticized on the MVP forum. When this happened to me in the aftermath of publishing my article on Temporary tables recently, I was taken aback, because these critics were experts whose views I respect. What was my crime? It was, I think, to suggest that, despite the obvious quirks, it was best to use Table Variables as a first choice, and to use local Temporary Tables if you hit problems due to these quirks, or if you were doing complex joins using a large number of rows. What are these quirks? Well, table variables have advantages if they are used sensibly, but this requires some awareness by the developer about the potential hazards and how to avoid them. You can be hit by a badly-performing join involving a table variable. Table Variables are a compromise, and this compromise doesn’t always work out well. Explicit indexes aren’t allowed on Table Variables, so one cannot use covering indexes or non-unique indexes. The query optimizer has to make assumptions about the data rather than using column distribution statistics when a table variable is involved in a join, because there aren’t any column-based distribution statistics on a table variable. It assumes a reasonably even distribution of data, and is likely to have little idea of the number of rows in the table variables that are involved in queries. However complex the heuristics that are used might be in determining the best way of executing a SQL query, and they most certainly are, the Query Optimizer is likely to fail occasionally with table variables, under certain circumstances, and produce a Query Execution Plan that is frightful. The experienced developer or DBA will be on the lookout for this sort of problem. In this blog, I’ll be expanding on some of the tests I used when writing my article to illustrate the quirks, and include a subsequent example supplied by Kevin Boles. A simplified example. We’ll start out by illustrating a simple example that shows some of these characteristics. We’ll create two tables filled with random numbers and then see how many matches we get between the two tables. We’ll forget indexes altogether for this example, and use heaps. We’ll try the same Join with two table variables, two table variables with OPTION (RECOMPILE) in the JOIN clause, and with two temporary tables. It is all a bit jerky because of the granularity of the timing that isn’t actually happening at the millisecond level (I used DATETIME). However, you’ll see that the table variable is outperforming the local temporary table up to 10,000 rows. Actually, even without a use of the OPTION (RECOMPILE) hint, it is doing well. What happens when your table size increases? The table variable is, from around 30,000 rows, locked into a very bad execution plan unless you use OPTION (RECOMPILE) to provide the Query Analyser with a decent estimation of the size of the table. However, if it has the OPTION (RECOMPILE), then it is smokin’. Well, up to 120,000 rows, at least. It is performing better than a Temporary table, and in a good linear fashion. What about mixed table joins, where you are joining a temporary table to a table variable? You’d probably expect that the query analyzer would throw up its hands and produce a bad execution plan as if it were a table variable. After all, it knows nothing about the statistics in one of the tables so how could it do any better? Well, it behaves as if it were doing a recompile. And an explicit recompile adds no value at all. (we just go up to 45000 rows since we know the bigger picture now)   Now, if you were new to this, you might be tempted to start drawing conclusions. Beware! We’re dealing with a very complex beast: the Query Optimizer. It can come up with surprises What if we change the query very slightly to insert the results into a Table Variable? We change nothing else and just measure the execution time of the statement as before. Suddenly, the table variable isn’t looking so much better, even taking into account the time involved in doing the table insert. OK, if you haven’t used OPTION (RECOMPILE) then you’re toast. Otherwise, there isn’t much in it between the Table variable and the temporary table. The table variable is faster up to 8000 rows and then not much in it up to 100,000 rows. Past the 8000 row mark, we’ve lost the advantage of the table variable’s speed. Any general rule you may be formulating has just gone for a walk. What we can conclude from this experiment is that if you join two table variables, and can’t use constraints, you’re going to need that Option (RECOMPILE) hint. Count Dracula and the Horror Join. These tables of integers provide a rather unreal example, so let’s try a rather different example, and get stuck into some implicit indexing, by using constraints. What unusual words are contained in the book ‘Dracula’ by Bram Stoker? Here we get a table of all the common words in the English language (60,387 of them) and put them in a table. We put them in a Table Variable with the word as a primary key, a Table Variable Heap and a Table Variable with a primary key. We then take all the distinct words used in the book ‘Dracula’ (7,558 of them). We then create a table variable and insert into it all those uncommon words that are in ‘Dracula’. i.e. all the words in Dracula that aren’t matched in the list of common words. To do this we use a left outer join, where the right-hand value is null. The results show a huge variation, between the sublime and the gorblimey. If both tables contain a Primary Key on the columns we join on, and both are Table Variables, it took 33 Ms. If one table contains a Primary Key, and the other is a heap, and both are Table Variables, it took 46 Ms. If both Table Variables use a unique constraint, then the query takes 36 Ms. If neither table contains a Primary Key and both are Table Variables, it took 116383 Ms. Yes, nearly two minutes!! If both tables contain a Primary Key, one is a Table Variables and the other is a temporary table, it took 113 Ms. If one table contains a Primary Key, and both are Temporary Tables, it took 56 Ms.If both tables are temporary tables and both have primary keys, it took 46 Ms. Here we see table variables which are joined on their primary key again enjoying a  slight performance advantage over temporary tables. Where both tables are table variables and both are heaps, the query suddenly takes nearly two minutes! So what if you have two heaps and you use option Recompile? If you take the rogue query and add the hint, then suddenly, the query drops its time down to 76 Ms. If you add unique indexes, then you've done even better, down to half that time. Here are the text execution plans.So where have we got to? Without drilling down into the minutiae of the execution plans we can begin to create a hypothesis. If you are using table variables, and your tables are relatively small, they are faster than temporary tables, but as the number of rows increases you need to do one of two things: either you need to have a primary key on the column you are using to join on, or else you need to use option (RECOMPILE) If you try to execute a query that is a join, and both tables are table variable heaps, you are asking for trouble, well- slow queries, unless you give the table hint once the number of rows has risen past a point (30,000 in our first example, but this varies considerably according to context). Kevin’s Skew In describing the table-size, I used the term ‘relatively small’. Kevin Boles produced an interesting case where a single-row table variable produces a very poor execution plan when joined to a very, very skewed table. In the original, pasted into my article as a comment, a column consisted of 100000 rows in which the key column was one number (1) . To this was added eight rows with sequential numbers up to 9. When this was joined to a single-tow Table Variable with a key of 2 it produced a bad plan. This problem is unlikely to occur in real usage, and the Query Optimiser team probably never set up a test for it. Actually, the skew can be slightly less extreme than Kevin made it. The following test showed that once the table had 54 sequential rows in the table, then it adopted exactly the same execution plan as for the temporary table and then all was well. Undeniably, real data does occasionally cause problems to the performance of joins in Table Variables due to the extreme skew of the distribution. We've all experienced Perfectly Poisonous Table Variables in real live data. As in Kevin’s example, indexes merely make matters worse, and the OPTION (RECOMPILE) trick does nothing to help. In this case, there is no option but to use a temporary table. However, one has to note that once the slight de-skew had taken place, then the plans were identical across a huge range. Conclusions Where you need to hold intermediate results as part of a process, Table Variables offer a good alternative to temporary tables when used wisely. They can perform faster than a temporary table when the number of rows is not great. For some processing with huge tables, they can perform well when only a clustered index is required, and when the nature of the processing makes an index seek very effective. Table Variables are scoped to the batch or procedure and are unlikely to hang about in the TempDB when they are no longer required. They require no explicit cleanup. Where the number of rows in the table is moderate, you can even use them in joins as ‘Heaps’, unindexed. Beware, however, since, as the number of rows increase, joins on Table Variable heaps can easily become saddled by very poor execution plans, and this must be cured either by adding constraints (UNIQUE or PRIMARY KEY) or by adding the OPTION (RECOMPILE) hint if this is impossible. Occasionally, the way that the data is distributed prevents the efficient use of Table Variables, and this will require using a temporary table instead. Tables Variables require some awareness by the developer about the potential hazards and how to avoid them. If you are not prepared to do any performance monitoring of your code or fine-tuning, and just want to pummel out stuff that ‘just runs’ without considering namby-pamby stuff such as indexes, then stick to Temporary tables. If you are likely to slosh about large numbers of rows in temporary tables without considering the niceties of processing just what is required and no more, then temporary tables provide a safer and less fragile means-to-an-end for you.

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  • Learning HTML5 - Best of RSS

    - by Albers
    These are some of the best RSS feeds I've found for keeping up with HTML5. I'm doing jQuery & MVC development as well so you will find the links have a jQuery/MS angle to them. WhenCanIUse The oh-so-necessary caniuse.com, in RSS update format: http://feeds.feedburner.com/WhenCanIUse ScriptJunkie http://services.social.microsoft.com/feeds/feed/query/tag/scriptjunkieLearn/eq/ns/DiscoveryFeedTool/eq/andA good HTML, JavaScript, CSS site hosted by MS Rachel Appel's blog http://rachelappel.com/rss?containerid=13HTML5, JavaScript, and MVC links with a general MS angle Smashing Magazine http://rss1.smashingmagazine.com/feed/Really high quality articles with a focus towards the design side of the web development picture IEBlog blogs.msdn.com/b/ie/rss.aspxNo surprise - the focus is on IE10, but it is really a great resource for new browser tech. MisfitGeek http://feeds.feedburner.com/MisfitGeekJoe recently switched from MS to Mozilla. New job but he still puts out great Weekly Links summaries. The Big Web Show http://feeds.feedburner.com/bigwebshowA podcast covering web development & design topics Elijah Manor/Web Dev .NET I'm cheating on this one a little bit. Elijah is a fantastic JS & web development resource. He has a site at Web Dev .NET, but honestly these days you are better off following him on Google+ ...and you can of course sign up to follow the W3C as well, although I don't think there is an HTML5-specific RSS feed. Good luck!

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