[Beowulf] itanium vs. x86-64
kyron at neuralbs.com
Wed Feb 11 04:12:43 PST 2009
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:
>>> 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."
>> Yes, Oprofile is a fantastic switch to turn on for profiling the entire
> 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
> 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)
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