From: Andi Kleen <ak@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Yan, Zheng" <zheng.z.yan@intel.com>,
linux-kernel@vger.kernel.org, mingo@elte.hu, eranian@google.com
Subject: Re: [RFC PATCH 5/7] perf, x86: use the PEBS auto reload mechanism when possible
Date: Wed, 28 May 2014 07:46:43 -0700 [thread overview]
Message-ID: <20140528144643.GG29957@tassilo.jf.intel.com> (raw)
In-Reply-To: <20140528075937.GO11096@twins.programming.kicks-ass.net>
On Wed, May 28, 2014 at 09:59:37AM +0200, Peter Zijlstra wrote:
> On Wed, May 28, 2014 at 02:18:08PM +0800, Yan, Zheng wrote:
> > When a fixed period is specified, this patch make perf use the PEBS
> > auto reload mechanism. This makes normal profiling faster, because
> > it avoids one costly MSR write in the PMI handler.
> >
>
> You can't do this unconditionally. Like I think you mention in the next
> patch, we need the PMI to fix up lots of cases.
There are two cases:
(1) Fixed period specified with PEBS.
The PMI still runs with threshold=1, but we can use the PEBS
auto-reload mechanism to automatically rewrite the counter which is
faster.
(2) Free running mode with more constraints
This is case (1)
-andi
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2014-05-28 14:46 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-28 6:18 [RFC PATCH 0/7] perf, x86: large PEBS interrupt threshold Yan, Zheng
2014-05-28 6:18 ` [RFC PATCH 1/7] perf, core: Add all PMUs to pmu_idr Yan, Zheng
2014-05-28 6:59 ` Peter Zijlstra
2014-05-28 6:18 ` [RFC PATCH 2/7] perf, core: introduce pmu context switch callback Yan, Zheng
2014-05-28 6:18 ` [RFC PATCH 3/7] perf, x86: use context switch callback to flush LBR stack Yan, Zheng
2014-05-28 6:18 ` [RFC PATCH 4/7] tools, perf: Allow the user to disable time stamps Yan, Zheng
2014-05-28 6:18 ` [RFC PATCH 5/7] perf, x86: use the PEBS auto reload mechanism when possible Yan, Zheng
2014-05-28 7:59 ` Peter Zijlstra
2014-05-28 14:46 ` Andi Kleen [this message]
2014-05-28 15:36 ` Peter Zijlstra
2014-05-28 6:18 ` [RFC PATCH 6/7] perf, x86: large PEBS interrupt threshold Yan, Zheng
2014-05-28 8:10 ` Peter Zijlstra
2014-05-28 12:54 ` Stephane Eranian
2014-05-28 15:02 ` Peter Zijlstra
2014-05-28 14:58 ` Andi Kleen
2014-05-28 15:24 ` Stephane Eranian
2014-05-28 16:51 ` Andi Kleen
2014-05-28 17:05 ` Stephane Eranian
2014-05-28 17:10 ` Peter Zijlstra
2014-05-28 17:12 ` Andi Kleen
2014-05-28 17:19 ` Peter Zijlstra
2014-05-28 17:45 ` Andi Kleen
2014-05-28 17:49 ` Peter Zijlstra
2014-05-28 17:09 ` Peter Zijlstra
2014-05-28 15:35 ` Peter Zijlstra
2014-05-28 16:08 ` Andi Kleen
2014-05-28 17:05 ` Peter Zijlstra
2014-05-28 17:25 ` Andi Kleen
2014-05-28 17:40 ` Stephane Eranian
2014-05-28 17:47 ` Andi Kleen
2014-05-28 19:28 ` Peter Zijlstra
2014-05-28 6:18 ` [RFC PATCH 7/7] perf, x86: drain PEBS buffer during context switch Yan, Zheng
2014-05-28 8:12 ` Peter Zijlstra
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