From: Andi Kleen <ak@linux.intel.com>
To: Vince Weaver <vweaver1@eecs.utk.edu>
Cc: Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Stephane Eranian <eranian@gmail.com>,
Lin Ming <ming.m.lin@intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
torvalds@linux-foundation.org
Subject: Re: [PATCH 1/1] perf tools: Add missing user space support for config1/config2
Date: Mon, 25 Apr 2011 15:12:58 -0700 [thread overview]
Message-ID: <20110425221258.GA21442@tassilo.jf.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1104251736220.12389@cl320.eecs.utk.edu>
> The PAPI tool was using the perf_events interface in the 2.6.39-git
> kernels to collect offcore response results by properly setting the
> config1 register on Nehalem and Westmere machines.
I already had some users for this functionality too. Offcore
events are quite useful for various analysis: basically every time
you have a memory performance problem -- especially a NUMA
problem -- they can help you a lot tracking it down.
They answer questions like "who accesses memory on another node"
As far as I'm concerned b52c55c6a25e4515b5e075a989ff346fc251ed09
is a bad feature regression.
>
> Now it has been disabled for unclear reasons.
Also unfortunately only partial. Previously you could at least
write the MSR from user space through /dev/cpu/*/msr, but now the kernel
randomly rewrites it if anyone else uses cache events.
Right now I have some frontend scripts which are doing this,
but it's really quite nasty.
It's very sad we have to go through this.
-Andi
next prev parent reply other threads:[~2011-04-25 22:13 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-21 17:41 [GIT PULL 0/1] perf/urgent Fix missing " Arnaldo Carvalho de Melo
2011-04-21 17:41 ` [PATCH 1/1] perf tools: Add missing user space " Arnaldo Carvalho de Melo
2011-04-22 6:34 ` Ingo Molnar
2011-04-22 8:06 ` Ingo Molnar
2011-04-22 21:37 ` Peter Zijlstra
2011-04-22 21:54 ` Peter Zijlstra
2011-04-22 22:19 ` Peter Zijlstra
2011-04-22 23:54 ` Andi Kleen
2011-04-23 7:49 ` Peter Zijlstra
2011-04-22 22:57 ` Peter Zijlstra
2011-04-23 0:00 ` Andi Kleen
2011-04-23 7:50 ` Peter Zijlstra
2011-04-23 8:13 ` Ingo Molnar
2011-07-01 15:23 ` [tip:perf/core] perf, arch: Add generic NODE cache events tip-bot for Peter Zijlstra
2011-04-25 17:12 ` [PATCH 1/1] perf tools: Add missing user space support for config1/config2 Vince Weaver
2011-04-25 17:54 ` Ingo Molnar
2011-04-25 21:46 ` Vince Weaver
2011-04-25 22:12 ` Andi Kleen [this message]
2011-04-26 7:23 ` Ingo Molnar
2011-04-26 7:38 ` Ingo Molnar
2011-04-26 20:51 ` Vince Weaver
2011-04-27 6:52 ` Ingo Molnar
2011-04-28 22:16 ` Vince Weaver
2011-04-28 23:30 ` Thomas Gleixner
2011-04-29 2:28 ` Andi Kleen
2011-04-29 19:32 ` Ingo Molnar
2011-04-26 9:49 ` Peter Zijlstra
2011-04-26 9:25 ` Peter Zijlstra
2011-04-26 20:33 ` Vince Weaver
2011-04-26 21:19 ` Cyrill Gorcunov
2011-04-26 21:25 ` Don Zickus
2011-04-26 21:33 ` Cyrill Gorcunov
2011-04-27 6:43 ` Ingo Molnar
2011-04-28 22:10 ` Vince Weaver
2011-04-22 16:22 ` Andi Kleen
2011-04-22 19:54 ` Ingo Molnar
2011-04-22 8:47 Stephane Eranian
2011-04-22 9:23 ` Ingo Molnar
2011-04-22 9:41 ` Stephane Eranian
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