linux-kernel - Re: [PATCH] bitops: simplify generic bit finding functions

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Date:	Mon, 28 Apr 2008 21:57:33 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Harvey Harrison <harvey.harrison@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>
Subject: Re: [PATCH] bitops: simplify generic bit finding functions

Linus Torvalds <torvalds@...ux-foundation.org> writes:
>
> Is there a real hot path anywhere that actually uses this and depends on 
> it?

A long time ago during profiling I found that in the scheduler back then
for_each_cpu() with find_next_bit() was somewhat hot. But I'm not sure it 
still would be in the new scheduler anyways and the test case a little
dumb anyways (overscheduling user space)

Still I think for_each_cpu() should be reasonably stream lined code.

-Andi
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