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From: Taeung Song <treeze.taeung@gmail.com>
To: Milian Wolff <milian.wolff@kdab.com>,
	perf group <linux-perf-users@vger.kernel.org>
Subject: Re: What unit is used by "period" for sleep time profiling?
Date: Wed, 24 Feb 2016 02:45:26 +0900	[thread overview]
Message-ID: <56CC9AB6.1080902@gmail.com> (raw)
In-Reply-To: <2312924.dtc4z5l04H@milian-kdab2>

Hi, Milian

On 02/23/2016 11:08 PM, Milian Wolff wrote:
> Hey all,
>
> following the "profiling sleep times" steps on the perf wiki at [1], we can
> get some "Period" numbers. The wiki e.g. shows a number of "502408738".

AFAIK,
When it comes to perf, "Period" means the number of occurrences
of an event, not the number of timer ticks.

The period is raw number of event count of sample.

Perf can collect partial samples from a lot of event
information(who/how much/when/etc.) or get all available samples.
(of course, there are some limits using actual hardware counters)

For example,

# perf record -e cycles -c 1000 sleep 5

As above, if -c option is used,
perf-record can collect a sample every 1000 occurrences
of event 'cycles' for 5 seconds. (sampling period = 1000)


Thanks,
Taeung

  reply	other threads:[~2016-02-23 17:45 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-23 14:08 What unit is used by "period" for sleep time profiling? Milian Wolff
2016-02-23 17:45 ` Taeung Song [this message]
2016-02-23 19:29   ` Milian Wolff

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