Re: Profiling a program's runtime

[Christoph Bartoschek <bartoschek@gmx.de>]

Am Freitag 04 Februar 2011 schrieb David Ahern:

> You can determine time blocked on read (and other system calls) by
> acquiring all context switches:
> 
>     perf record -e cs -c 1 -a
> 
> From there you'll want to generate a time history output. To use
> unmodified perf code use the -D option to dump raw samples (perf report
> -D). You can find the process of interest and the kernel timestamp
> between schedule out events -- and the sched out event before your
> process. Together you can piece together the time you blocked on read.
> 
> Alternatively, there are add-on patches which dump the timehistory in a
> pretty print format:
> 
> http://www.mail-archive.com/linux-perf-users@vger.kernel.org/msg00049.html
> http://www.mail-archive.com/linux-perf-users@vger.kernel.org/msg00047.html
> http://www.mail-archive.com/linux-perf-users@vger.kernel.org/msg00048.html
> 
> 
> That output can be manipulated much easier to determine time on the
> processor and time between schedule-in events.
> 
> Not the complete picture of what I think you are looking for -- but a
> way to get the time blocked on syscall stats via perf.

Looks quite complicated to get such a profile. However I have to check it, 
when I'm back at work.

Thanks
Christoph