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Peter Kjellstrom wrote:
<blockquote cite="mid:200902110939.07718.cap@nsc.liu.se" type="cite">
<pre wrap="">On Wednesday 11 February 2009, Eric Thibodeau wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Tom Elken wrote:
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">Which profilers can
benefit from all this info?
</pre>
</blockquote>
<pre wrap="">We have found Oprofile to be a useful text-oriented tool:
<a class="moz-txt-link-freetext" href="http://oprofile.sourceforge.net/about/">http://oprofile.sourceforge.net/about/</a>
>From the Overview on this page:
"OProfile is a system-wide profiler for Linux systems, capable of
profiling all running code at low overhead. OProfile is released under
the GNU GPL.
It consists of a kernel driver and a daemon for collecting sample data,
and several post-profiling tools for turning data into information.
OProfile leverages the hardware performance counters of the CPU to enable
profiling of a wide variety of interesting statistics, which can also be
used for basic time-spent profiling. All code is profiled: hardware and
software interrupt handlers, kernel modules, the kernel, shared
libraries, and applications."
-Tom
</pre>
</blockquote>
<pre wrap="">Yes, Oprofile is a fantastic switch to turn on for profiling the entire
system.
</pre>
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<pre wrap=""><!---->
Compared to Tau it is _very_ simplistic and won't take long to learn (that
scores points for both Oprofile and Tau depending on what you want).
</pre>
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Well, I was assuming this was the Beowulf ML and that people are
usually interested in parallel stuff ;) I'll agree that, TAU is a
beast, mostly due to its versatility which requires attention when
setting up. But, IMHO, using it is quite simple and it provides
intuitive and powerful viewing tools. The only issue I have for the
moment is one of the interfaces being very slow to generate
graphs...can't pinpoint why...guess I'll have to profile TAU :P<br>
<br>
<blockquote cite="mid:200902110939.07718.cap@nsc.liu.se" type="cite">
<blockquote type="cite">
<pre wrap="">Now, last time I tried to use it it totally crashed my system.
</pre>
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<pre wrap=""><!---->
I've used Oprofile many times over the last few years and on many different
systems and have yet to see one crash.
</pre>
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Yeah, like I said, _my_ single use crashed the system and I had to move
forward.<br>
<blockquote cite="mid:200902110939.07718.cap@nsc.liu.se" type="cite">
<pre wrap="">
...
Worth noting here is that Oprofile uses its own kernel module (which ships
with current kernels from both CentOS-5/RHEL5 and kernel.org) while Tau
depends on PAPI.
PAPI typically uses the perfctr kernel module/patch which you'll have to patch
into your kernel on your own and it conflicts (run time) with Oprofile.
Alternatively you can build PAPI on top of perfmon2 (also probably a kernel
patch) but this I havn't tried.
</pre>
</blockquote>
Yes in both cases. I just recently patched a 2.6.28 gentoo-sources with
no problems but only using the perfctr patch set from it's homepage
(the one packaged with PAPI lags too much)<br>
<blockquote cite="mid:200902110939.07718.cap@nsc.liu.se" type="cite">
<pre wrap="">
/Peter
</pre>
</blockquote>
Eric
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