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Date:      Mon, 17 Jan 2011 09:45:44 +0100
From:      Fabien Thomas <fabien.thomas@netasq.com>
To:        Garrett Cooper <gcooper@FreeBSD.org>
Cc:        George Neville-Neil <gnn@freebsd.org>, freebsd-current@freebsd.org, Ryan Stone <rysto32@gmail.com>, Steve Kargl <sgk@troutmask.apl.washington.edu>
Subject:   Re: Profiling code execution on amd64?
Message-ID:  <88A95F5C-FDE9-425C-AC1B-D90B66A51B9C@netasq.com>
In-Reply-To: <AANLkTikYk0MP=gBnxz3%2BkjF_nRKyqQQO5VK2wUUnRQyM@mail.gmail.com>
References:  <20110113171139.GA32250@troutmask.apl.washington.edu> <AANLkTi=C4L9fn7q8PfJgY=8c24BQnZTC9s7BubsrUYxv@mail.gmail.com> <20110114040549.GA36430@troutmask.apl.washington.edu> <1D4725BB-0A0A-44FB-9FF1-23969C469AA6@freebsd.org> <20110115061023.GA41547@troutmask.apl.washington.edu> <AANLkTikYk0MP=gBnxz3%2BkjF_nRKyqQQO5VK2wUUnRQyM@mail.gmail.com>

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Last time i've used it it was working but I dont think it is really =
useful now (from my POV) because
you cant have a global view of the system with it and all other reports =
overlap.

With the current state you have:
- top mode for fast lookup
- text output (replace gprof for me)
- kcachegrind (calltree) for in depth analysis
- gprof=20

Fabien

> On Fri, Jan 14, 2011 at 10:10 PM, Steve Kargl
> <sgk@troutmask.apl.washington.edu> wrote:
>> On Fri, Jan 14, 2011 at 03:40:46PM -0500, George Neville-Neil wrote:
>>>=20
>>> On Jan 13, 2011, at 23:05 , Steve Kargl wrote:
>>>=20
>>>> On Thu, Jan 13, 2011 at 10:08:30PM -0500, Ryan Stone wrote:
>>>>> I would suggest using hwpmc for profiling:
>>>>>=20
>>>>> # kldload hwpmc
>>>>> # pmcstat -S unhalted-cycles -O /tmp/samples.out ../penetration
>>>>> # pmcstat -R /tmp/samples.out -G /tmp/penetration.txt
>>>>>=20
>>>>>=20
>>>>> 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.
>>>>=20
>>>>=20
>>>> Thanks.  I'll give it a try, but my initial attempt seems to
>>>> indicate that one needs to be root to use hwpmc.
>>>>=20
>>>> 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
>>>>=20
>>>=20
>>> You only need to be root to profile the kernel or someone else's =
process.
>>>=20
>>> This tutorial might help:
>>>=20
>>> www.dcbsdcon.org/speakers/slides/neville-neil_dcbsdcon2009.pdf
>>>=20
>>=20
>> Thanks.  I'll look at the tutorial.  Meanwhile, should gprof
>> be removed from the base system because it appears broken?
>=20
> Instead of just removing things, why not determine why things are
> broken and try to fix them?
> -Garrett
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