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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Dimitri Sivanich <sivanich@sgi.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@elte.hu>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [patch 0/3] move calc_load to softirq
Date: Sat, 02 May 2009 19:06:25 -0000	[thread overview]
Message-ID: <20090502190500.513452861@linutronix.de> (raw)

calc_load() calculates the load average, which is a rough estimate at
best. Right now calc_load() is called from do_timer() under the xtime
lock write locked and with interrupts disabled. Dimitri Sivanich
noticed 55us xtime lock hold times on a 64 cpu system. He suggested to
split calc_load() out of do_timer() and move it out of the xtime
locked section of each caller of do_timer():
http://lkml.org/lkml/2009/4/10/318

The following patch series moves the load average calculation to the
timer softirq and removes the xtime lock dependency in the generic
code. This reduces also the interrupt off section of the timer
interrupt.

Thanks,

	tglx




             reply	other threads:[~2009-05-02 19:08 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-02 19:06 Thomas Gleixner [this message]
2009-05-02 19:06 ` [patch 1/3] timers: use function instead of macro for calc_load Thomas Gleixner
2009-05-07 18:16   ` Dimitri Sivanich
2009-05-02 19:06 ` [patch 2/3] timer: move calc_load to softirq Thomas Gleixner
2009-05-02 19:24   ` Andrew Morton
2009-05-02 19:54     ` Thomas Gleixner
2009-05-07 18:18       ` Dimitri Sivanich
2009-05-02 19:06 ` [patch 3/3] tiemrs: cleanup avenrun users Thomas Gleixner

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