From: Thomas Gleixner <tglx@linutronix.de>
To: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Harvey Harrison <harvey.harrison@gmail.com>,
Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH] bitops: simplify generic bit finding functions
Date: Mon, 28 Apr 2008 17:58:44 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.1.10.0804281757340.3261@apollo.tec.linutronix.de> (raw)
In-Reply-To: <1209395443.25700.1250273669@webmail.messagingengine.com>
On Mon, 28 Apr 2008, Alexander van Heukelum wrote:
> > See patch below. It gives back the 1400 bytes on SPARC64 and other
> > platforms that have no instruction for find bit.
>
> Hi,
>
> I, personally, see this patch as a stopgap measure. The real problem
> is that the generic __ffs is inlined and ends up generating a lot
> of instructions.
>
> Until the generic implementation of __ffs is fixed not to be an
> enormous inline function, this seems to be a reasonable thing
> to do, though it's a shame that the optimization is now default-
> off for architectures with a good implementation of __ffs.
Yup, it hasn't been there before and we explicitely enable it on
x86. If there are other archs which have a good one it's a nobrainer
to enable it.
Thanks,
tglx
next prev parent reply other threads:[~2008-04-28 16:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-27 20:19 Harvey Harrison
2008-04-27 20:26 ` Linus Torvalds
2008-04-27 20:29 ` Harvey Harrison
2008-04-27 20:36 ` Al Viro
2008-04-27 20:38 ` Harvey Harrison
2008-04-27 20:38 ` Linus Torvalds
2008-04-27 21:02 ` Al Viro
2008-04-28 14:04 ` Thomas Gleixner
2008-04-28 15:10 ` Alexander van Heukelum
2008-04-28 15:58 ` Thomas Gleixner [this message]
2008-04-28 16:25 ` Linus Torvalds
2008-04-28 16:47 ` Thomas Gleixner
2008-04-28 16:54 ` Linus Torvalds
2008-04-28 19:26 ` Thomas Gleixner
2008-04-28 19:37 ` Linus Torvalds
2008-04-28 21:55 ` Ingo Molnar
2008-04-29 10:01 ` [PATCH] bitops: remove "optimizations" Thomas Gleixner
2008-04-29 10:03 ` David Miller
2008-04-29 12:34 ` David Miller
2008-04-29 14:20 ` Ingo Molnar
2008-04-29 22:31 ` David Miller
2008-04-29 16:51 ` Thomas Gleixner
2008-04-29 22:58 ` David Miller
2008-04-29 23:30 ` David Miller
2008-04-28 19:57 ` [PATCH] bitops: simplify generic bit finding functions Andi Kleen
2008-04-28 14:58 ` Alexander van Heukelum
2008-04-28 14:32 ` Alexander van Heukelum
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