From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
mingo@elte.hu, Lin Ming <ming.m.lin@intel.com>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [BUG] perf_event: inst_retired:any_p:c=16:i=1 is not equivalent to cpu_clk_unhalted:thread_p
Date: Tue, 18 Jan 2011 19:36:33 +0100 [thread overview]
Message-ID: <1295375793.30950.1056.camel@laptop> (raw)
In-Reply-To: <AANLkTinVc=VRo+2=M3x5HEoF__SOJn7kBk7Ek0R94TG9@mail.gmail.com>
On Tue, 2011-01-18 at 19:05 +0100, Stephane Eranian wrote:
> Peter,
>
> commit 7639dae0ca11038286bbbcda05f2bef601c1eb8d
> Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Tue Dec 14 21:26:40 2010 +0100
>
> perf, x86: Provide a PEBS capable cycle event
>
>
>
> Even with the transformation cmask=16:invert=1, you are not quite
> counting the same thing.
>
> inst_retired:any_p:c=16:i=1 is different from cpu_clk_unhalted:thread_p
>
> Simply because, I think, this form of inst_retired counts in HALTED state.
Drad it does indeed:
# perf stat -a -e cycles:p -e cycles sleep 1
Performance counter stats for 'sleep 1':
61,634,870 cycles
26,703,249 cycles
1.000860820 seconds time elapsed
> This automatic transformation would be "okay" in per-thread mode, but
> not in system-wide mode. It should not be done under the cover. I would
> rather have this option at the user level.
Agreed, since its not identical it had best be done in userspace, too
bad :/ I'll revert this patch.
next prev parent reply other threads:[~2011-01-18 18:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-18 18:05 [BUG] perf_event: inst_retired:any_p:c=16:i=1 is not equivalent to cpu_clk_unhalted:thread_p Stephane Eranian
2011-01-18 18:36 ` Peter Zijlstra [this message]
2011-01-18 20:26 ` Stephane Eranian
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