Re: [PerfSuite-users] psrun profile doesn't show any sampling point

[Cheng L. <cyl...@gm...>]

Rick,

Here is my 'psinv -V' output for the particular machine on which I am seeing
the negative numbers of
sampling points.

[cliao@maui1 bin]$ psinv -V
        --------------------------------------------
                       PerfSuite 0.6.2a6
                          psinv 0.6
                  University of Illinois/NCSA
                      Open Source License
                http://perfsuite.ncsa.uiuc.edu/
               http://perfsuite.sourceforge.net/
        --------------------------------------------
I also have PerfSuite 0.6.2 installed on different machines, but haven't run
any large job on those machines yet.

To track down the incorrect libc offset on Linux, I simply pored throu the
xml file and ran addr2line manually
for the samples that were pertinent to the executable to see if I got a lot
of ??.  No luck there, but I was able to
conclude the libc offset should be zero after I did a 'nm libc.so.6' and saw
pretty similiar addresses from the nm
output and the xml file.

The software company I am working for also has a large PC/Windows customer
base...

Thanks,
Cheng





On Wed, Aug 19, 2009 at 12:25 PM, Rick Kufrin <rk...@il...> wrote:

> Cheng,
>
> These are some interesting observations and questions.   I have a few
> comments, but first one question: which release of PerfSuite are you
> running? To find out, do "psinv -V", and it will appear at the top.  The
> reason why I ask this is that the appearance of negative sample counts is a
> problem that I believe was addressed already, a fix checked in quite a while
> ago.  If the release you are using is after that fix, then apparently we
> still have an issue (and I thank you for your report in advance).
>
> Second, I am glad you resolved (apparently) an incorrect offset, but I am
> curious to know how you verify that this provided a fix.  It is not unusual
> to see question marks (PCs that cannot be mapped to source locations).
>
> Regarding the sampling bin size: that is a fixed size, and it is currently
> the size of an unsigned short, which should allow for up to 64K samples to
> map to any one bin.  After that, overflow would occur and you would
> effectively lose samples and get an incorrect profile.  The only solution at
> present, unfortunately and as you suggest, is to increase the sampling
> period to reduce overall sample counts.
>
> Rick
>
>
> Cheng Liao wrote:
>
>> Rick,
>>  The large ?? entry in my profile is caused by an incorrect offset for
>> libc.so.6 base
>> address.  I need to manually set the libc offset to zero in the xml file,
>> then run psprocess, to
>> fix the problem.
>>  A new problem I have encountered is for large jobs, the bin for the
>> number of sampling points would overflow:
>>                                   <sample pc="59d770">27665</sample>
>>                                <sample pc="59d772">26940</sample>
>>                                <sample pc="59d776">27564</sample>
>>                                <sample pc="59d77a">-31502</sample>
>>  <---------- negative
>>                                <sample pc="59d77e">11502</sample>
>>                                <sample pc="59d782">5323</sample>
>>                                <sample pc="59d78a">21065</sample>
>>                                <sample pc="59d78e">32422</sample>
>>                                <sample pc="59d790">27709</sample>
>>                                <sample pc="59d794">-30384</sample>
>> <------------- negative
>>                                <sample pc="59d798">24312</sample>
>> Does perfsuite support a large sampling point bin, or using a higher
>> profiling overflow threhold would be the only solution?
>>  Thanks,
>> Cheng
>>
>>
>