From: Mike Galbraith <bitbucket@online.de>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Andi Kleen <ak@linux.intel.com>,
lenb@kernel.org, tglx@linutronix.de, peterz@infradead.org
Subject: Re: [PATCH] Trace idle entry and exit times
Date: Sat, 07 Dec 2013 05:57:32 +0100 [thread overview]
Message-ID: <1386392252.5673.31.camel@marge.simpson.net> (raw)
In-Reply-To: <1386377164-2223-1-git-send-email-andi@firstfloor.org>
On Fri, 2013-12-06 at 16:46 -0800, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> This patch creates 4 new trace points: one at the beginning of idle,
> one before entering mwait, one after exiting mwait, and one after
> finishing the idle code. This is useful to trace down any
> additional latencies caused by the ever-growing idle code.
>
> Idle latencies are a common source of performance problems, so it's
> important to be able to measure them.
You mean stuff like.. oh, say 60 cores doing zero work every 12ms
munching ~20% cpu?
- 97.57% [kernel] [k] _raw_spin_lock_irqsave ▒
- _raw_spin_lock_irqsave ▒
- 97.02% clockevents_notify ◆
intel_idle ▒
cpuidle_idle_call ▒
cpu_idle ▒
- 2.97% tick_broadcast_oneshot_control ▒
tick_notify ▒
notifier_call_chain ▒
clockevents_notify ▒
intel_idle ▒
cpuidle_idle_call ▒
cpu_idle
C2 is super green, it's hug'n the sh*t outta them trees :)
-Mike
next prev parent reply other threads:[~2013-12-07 4:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-07 0:46 [PATCH] Trace idle entry and exit times Andi Kleen
2013-12-07 4:57 ` Mike Galbraith [this message]
2013-12-07 5:20 ` Andi Kleen
2013-12-07 8:22 ` Mike Galbraith
2013-12-07 17:29 ` Andi Kleen
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