linux-kernel - Memory management timer optimizations for power saving

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Message-ID: <1F18D6510CF0474A8C9500565A7E41A20544D91D8C@NOK-EUMSG-02.mgdnok.nokia.com>
Date:	Mon, 18 May 2009 14:40:59 +0200
From:	<Tero.Kristo@...ia.com>
To:	<linux-kernel@...r.kernel.org>
Subject: Memory management timer optimizations for power saving

Hi,

I've been looking at some timer optimizations for the kernel to get it to sleep as long as possible, and to allow maximum power saving in embedded ARM environment. One of the most severe timer users appears to be memory management, with reap_work and wb_timer expiring rather often (I am seeing something like one timer expiring every two seconds or so.) In the attached patch I have changed the timers to deferred type, i.e. they can be delayed until next wakeup occurs from some other source, like another timer or some peripheral I/O. Can you see any problems doing something like this? A potential issue could be that some data writeback to permanent storage gets delayed, and in case of a sudden power loss it might be lost completely.

-Tero

Download attachment "0001-Memory-management-timer-optimizations-for-power-savi.patch" of type "application/octet-stream" (1221 bytes)