[PATCH] sched: avoid div in rebalance_tick

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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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Nick Piggin 2007-02-12 00:53:51 -08:00 • committed by Linus Torvalds

parent 0a9ac38246

commit ff91691bcc

1 changed files with 5 additions and 3 deletions

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kernel/sched.c

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