From: Nick Piggin <npiggin@suse.de>
Date: Mon, 12 Feb 2007 08:53:51 +0000 (-0800)
Subject: [PATCH] sched: avoid div in rebalance_tick
X-Git-Tag: v2.6.21-rc1~274^2~96
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ff91691bccdb741efb2df0489058a4961fa79598;p=pandora-kernel.git

[PATCH] sched: avoid div in rebalance_tick

Avoid expensive integer divide 3 times per CPU per tick.

A userspace test of this loop went from 26ns, down to 19ns on a G5; and
from 123ns down to 28ns on a P3.

(Also avoid a variable bit shift, as suggested by Alan. The effect
of this wasn't noticable on the CPUs I tested with).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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