From: Alan <alan@lxorguk.ukuu.org.uk>
To: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@osdl.org>, Ingo Molnar <mingo@elte.hu>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [patch] sched: avoid div in rebalance_tick
Date: Fri, 12 Jan 2007 09:59:40 +0000 [thread overview]
Message-ID: <20070112095940.0795a998@localhost.localdomain> (raw)
In-Reply-To: <20070112060213.GB28611@wotan.suse.de>
On Fri, 12 Jan 2007 07:02:13 +0100
Nick Piggin <npiggin@suse.de> wrote:
> Just noticed this while looking at a bug.
> Avoid an expensive integer divide 3 times per CPU per tick.
Integer divide is cheap on some modern processors, and multibit shift
isn't on all embedded ones.
How about putting back scale = 1 and using
scale += scale;
instead of the shift and getting what ought to be even better results
next prev parent reply other threads:[~2007-01-12 9:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-12 6:02 [patch] sched: avoid div in rebalance_tick Nick Piggin
2007-01-12 9:59 ` Alan [this message]
2007-01-12 10:27 ` Nick Piggin
2007-01-13 6:46 ` Nick Piggin
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