Re: Profiling code execution on amd64?

On Jan 13, 2011, at 23:05 , Steve Kargl wrote:

> On Thu, Jan 13, 2011 at 10:08:30PM -0500, Ryan Stone wrote:
>> I would suggest using hwpmc for profiling:
>> 
>> # kldload hwpmc
>> # pmcstat -S unhalted-cycles -O /tmp/samples.out ../penetration
>> # pmcstat -R /tmp/samples.out -G /tmp/penetration.txt
>> 
>> 
>> You can also get pmcstat to generate gprof-compatible output with -g,
>> but I never use the mode so I'm really not sure what it gives you.  I
>> think that you have to run gprof on the output or something, but don't
>> hold me to that.
> 
> 
> Thanks.  I'll give it a try, but my initial attempt seems to
> indicate that one needs to be root to use hwpmc.  
> 
> laptop:kargl[210] pmcstat -S unhalted-cycles -O /tmp/samples.out ../penetration
> pmcstat: ERROR: Cannot allocate system-mode pmc with specification
> "unhalted-cycles": Operation not permitted
> 

You only need to be root to profile the kernel or someone else's process.

This tutorial might help:

www.dcbsdcon.org/speakers/slides/neville-neil_dcbsdcon2009.pdf

Best,
George