pmcstat and squid

[Joseph Koshy]

> I'm trying to use pmcstat to profile userspace time used in
> Squid. I just can't seem to get pmcstat to report anything
> useful.
>
> The last thing I tried was something like:
>
> # pmcstat -O file -P instructions -t <pid of squid>
> # pmcstat -R file -g
> # ls k7-retired-instructions
> kernel.gmon
>
> There doesn't seem to be a good example for
> process-based counting stuff with PMC. Could anyone
> give me a hand?
>
> Thanks!

I can think of one of two scenarios:

 1) the squid process was in the kernel when the
    samples got taken.  This could happen if the
    process was say in select() handling all the time.
 2) There a bug in my process handling code that is
    being triggered (hwpmc undercounts process-mode
    samples), and samples are being missed.

Regards,
Koshy