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

[Rick K. <rk...@il...>]

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
>