From: Kyle McMartin <kyle@mcmartin.ca>
To: Adrian Bunk <bunk@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: RFC: remove __read_mostly
Date: Thu, 13 Dec 2007 18:54:32 -0500 [thread overview]
Message-ID: <20071213235432.GA26669@fattire.cabal.ca> (raw)
In-Reply-To: <20071213222044.GH21616@stusta.de>
On Thu, Dec 13, 2007 at 11:20:44PM +0100, Adrian Bunk wrote:
> Is there anywhere in the kernel a case where __read_mostly brings a
> measurable improvement or can it be removed?
>
Yes, definitely[1]... the problem is, and this is also true of other
annotations[2], that people go absolutely nuts adding these annotations
without doing any profiling to see whether they actually improve things.
I'd bet, in the __read_mostly case at least, that there's no
improvement in almost all cases.
cheers, Kyle
1. It's hugely relevant on big-SMP machines.
2. I mean __read_mostly, likely, unlikely, etc., not the useful sparse
annotations.
next prev parent reply other threads:[~2007-12-13 23:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-13 22:20 RFC: remove __read_mostly Adrian Bunk
2007-12-13 22:29 ` Andi Kleen
2007-12-13 22:41 ` Adrian Bunk
2007-12-14 16:16 ` Arnd Bergmann
2007-12-14 16:31 ` Eric Dumazet
2007-12-13 22:32 ` David Miller
2007-12-13 22:44 ` Harvey Harrison
2007-12-13 23:06 ` Andi Kleen
2007-12-13 22:48 ` Eric Dumazet
2007-12-13 23:00 ` Adrian Bunk
2007-12-13 23:54 ` Kyle McMartin [this message]
2007-12-14 0:33 ` Andi Kleen
2007-12-17 10:33 ` Andrew Morton
2007-12-17 10:53 ` Eric Dumazet
2007-12-17 11:07 ` Andrew Morton
2007-12-17 12:19 ` Andi Kleen
2007-12-17 12:15 ` Andi Kleen
2007-12-17 12:40 ` Adrian Bunk
2007-12-14 15:24 ` Matt Mackall
2007-12-14 15:38 ` Eric Dumazet
2007-12-14 15:42 ` Matt Mackall
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