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Lots of samples -- few stack walks. How come? RRS feed

  • Question

  • Hi,

     

    I am trying to understand an oddity I am having with the sampling profiler.  Basically, I seem to be missing a lot of samples; that is, I see a count of 3584 application samples, but only get 616 stack walks.  This is vastly different from similar profile information for the previous version of my application (which I'm comparing against) where I have 2104 application samples and get 2097 stack walks.

     

    I see how I could have some missed stack walks, but why would the percentage be so high?  Is there some explanation?

     

    I have tried VS2005 and (now) VS2008 Beta2 and am running 32-bit Windows XP (if that matters)

     

    I was going to paste my performance report properties windows captures, but they don't show up in this editor.  Here's the text equivalent (assuming I didn't introduce any typos):

     

    For "good" profile:

    Callbacks (Stack Walks)                  2097

    Samples (Aborted)                          0

    Samples (Application)                    2104

    Samples (Broken)                            2097

    Samples (Callback)                          2104

    Samples (Kernel)                             264

    Samples (Other)                               28

    Samples (Overhead)                      923

    Samples (Total)                                 3319

     

    For "bad" profile:

    Callbacks (Stack Walks)                  616

    Samples (Aborted)                          0

    Samples (Application)                    3584

    Samples (Broken)                            616

    Samples (Callback)                          3584

    Samples (Kernel)                             297

    Samples (Other)                               33

    Samples (Overhead)                      859

    Samples (Total)                                 4773

     

    Does anyone have any ideas?  I apologize in advance if this question has been asked before -- I didn't find it in my travels through this forum.

     

    Thanks,

    Ken

    Wednesday, September 26, 2007 11:37 PM

Answers

  • Ken,

     

    You are right in that a large number of samples appear to not have worked correctly. I dug into the issue and found that we had a driver statistics bug that we fixes just a little after Beta 2 was released. So the fix for this should be in the RTM product. If you want to try a workaround you could try doing a vsperfcmd /adminBig Smileriver,uninstall before you run your performance scenario. VSPerfCmd is found in the Team Tools\Performance Tools directory under the main visual studio directory. But I'm not 100% sure that this will fix the issue.

     

    Thanks,

    Ian

     

    Wednesday, October 3, 2007 9:49 PM