Peter Kjellstrom wrote:
On Wednesday 11 February 2009, Eric Thibodeau wrote:
Tom Elken wrote:
Which profilers can
benefit from all this info?
We have found Oprofile to be a useful text-oriented tool:
http://oprofile.sourceforge.net/about/
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
Yes, Oprofile is a fantastic switch to turn on for profiling the entire
system.
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).
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
Now, last time I tried to use it it totally crashed my system.
I've used Oprofile many times over the last few years and on many different
systems and have yet to see one crash.
Yeah, like I said, _my_ single use crashed the system and I had to move
forward.
...
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.
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)
/Peter
Eric
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