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From: Andi Kleen <ak@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kan Liang <kan.liang@intel.com>,
	peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
	linux-kernel@vger.kernel.org, eranian@google.com,
	jolsa@kernel.org
Subject: Re: [PATCH 0/3]measure SMI cost
Date: Fri, 24 Mar 2017 04:40:51 -0700	[thread overview]
Message-ID: <20170324114051.GC9371@tassilo.jf.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1703240942590.3688@nanos>

> > A new --smi-cost mode in perf stat is implemented to measure the SMI cost
> > by calculating cycles and aperf results. In practice, the percentages of
> > SMI cycles should be more useful than absolute value.
> 
> That's only true for performance oriented analysis, but for analyzing the
> root cause of latencies the actual cycles are definitely interesting.

perf stat also prints the absolute cycles of course (unless you do --metric-only)

It cannot print individual cycles (per SMI occurrence), the only
way to do that would be to poll constantly.

-Andi

  reply	other threads:[~2017-03-24 11:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-23 18:25 [PATCH 0/3]measure SMI cost kan.liang
2017-03-23 18:25 ` [PATCH 1/3] perf/x86: add sysfs entry to freeze counter on SMI kan.liang
2017-03-23 20:31   ` Peter Zijlstra
2017-03-23 20:48     ` Liang, Kan
2017-03-23 22:23     ` Andi Kleen
2017-03-24  8:16       ` Peter Zijlstra
2017-03-23 20:32   ` Peter Zijlstra
2017-03-24  8:31     ` Thomas Gleixner
2017-03-24 14:15       ` Liang, Kan
2017-03-24 14:23         ` Peter Zijlstra
2017-03-23 18:25 ` [PATCH 2/3] tools lib api fs: Add sysfs__write_int function kan.liang
2017-03-28  3:38   ` Elliott, Robert (Persistent Memory)
2017-03-23 18:25 ` [PATCH 3/3] perf stat: Add support to measure SMI cost kan.liang
2017-03-24  8:44 ` [PATCH 0/3]measure " Thomas Gleixner
2017-03-24 11:40   ` Andi Kleen [this message]
2017-03-24 12:07     ` Thomas Gleixner
2017-03-24 14:14       ` Liang, Kan
2017-03-31 21:51 ` Stephane Eranian
2017-04-01  1:41   ` Liang, Kan

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