From: Eric Dumazet <dada1@cosmosbay.com>
To: Andrew Morton <akpm@osdl.org>
Cc: Andi Kleen <ak@muc.de>,
ashok.raj@intel.com, ntl@pobox.com, riel@redhat.com,
linux-kernel@vger.kernel.org, torvalds@osdl.org, mingo@elte.hu,
76306.1226@compuserve.com, wli@holomorphy.com,
heiko.carstens@de.ibm.com, pj@sgi.com
Subject: Re: [PATCH] percpu data: only iterate over possible CPUs
Date: Fri, 10 Feb 2006 12:09:39 +0100 [thread overview]
Message-ID: <43EC7473.20109@cosmosbay.com> (raw)
In-Reply-To: <20060210024222.67db06f3.akpm@osdl.org>
Andrew Morton a écrit :
> Andi Kleen <ak@muc.de> wrote:
>> On Thursday 09 February 2006 19:04, Andrew Morton wrote:
>>> Ashok Raj <ashok.raj@intel.com> wrote:
>>>> The problem was with ACPI just simply looking at the namespace doesnt
>>>> exactly give us an idea of how many processors are possible in this platform.
>>> We need to fix this asap - the performance penalty for HOTPLUG_CPU=y,
>>> NR_CPUS=lots will be appreciable.
>> What is this performance penalty exactly?
>
> All those for_each_cpu() loops will hit NR_CPUS cachelines instead of
> hweight(cpu_possible_map) cachelines.
You mean NR_CPUS bits, mostly all included in a single cacheline, and even in
a single long word :) for most cases (NR_CPUS <= 32 or 64)
next prev parent reply other threads:[~2006-02-10 11:11 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200602051959.k15JxoHK001630@hera.kernel.org>
2006-02-07 15:15 ` [PATCH] percpu data: only iterate over possible CPUs Heiko Carstens
2006-02-07 15:31 ` Jens Axboe
2006-02-07 16:25 ` Eric Dumazet
2006-02-07 16:42 ` Linus Torvalds
2006-02-07 17:34 ` Andrew Morton
2006-02-07 17:48 ` Linus Torvalds
2006-02-07 18:30 ` Dipankar Sarma
2006-02-07 18:43 ` Linus Torvalds
2006-02-07 18:53 ` Dipankar Sarma
2006-02-07 19:11 ` Linus Torvalds
2006-02-08 4:40 ` Heiko Carstens
2006-02-08 8:55 ` Ivan Kokshaysky
2006-02-08 22:31 ` Rik van Riel
2006-02-09 1:20 ` Rik van Riel
2006-02-09 1:20 ` Rik van Riel
2006-02-09 3:05 ` Andrew Morton
2006-02-09 3:08 ` Andrew Morton
2006-02-09 4:36 ` Eric Dumazet
2006-02-09 4:45 ` Andrew Morton
2006-02-09 4:56 ` Paul Jackson
2006-02-09 16:08 ` Nathan Lynch
2006-02-09 16:13 ` Heiko Carstens
2006-02-09 16:38 ` Rik van Riel
2006-02-09 16:59 ` Nathan Lynch
2006-02-09 17:37 ` Andi Kleen
2006-02-10 10:05 ` Heiko Carstens
2006-02-10 10:13 ` Andi Kleen
2006-02-11 14:49 ` Heiko Carstens
2006-02-11 18:04 ` Andi Kleen
2006-02-09 17:03 ` Ashok Raj
2006-02-09 17:23 ` Nathan Lynch
2006-02-09 18:04 ` Andrew Morton
2006-02-09 18:52 ` Ashok Raj
2006-02-09 20:37 ` Andrew Morton
2006-02-09 21:03 ` Ashok Raj
2006-02-10 10:02 ` Andi Kleen
2006-02-10 10:42 ` Andrew Morton
2006-02-10 11:09 ` Eric Dumazet [this message]
2006-02-10 11:23 ` Andrew Morton
2006-02-10 11:26 ` Andrew Morton
2006-02-10 14:13 ` Eric Dumazet
2006-02-11 0:10 ` Nathan Lynch
2006-02-11 0:25 ` Andrew Morton
2006-02-10 12:10 ` Andi Kleen
2006-02-10 19:08 ` Andrew Morton
2006-02-09 4:39 ` Eric Dumazet
2006-02-09 4:46 ` Nick Piggin
2006-02-09 8:32 Chuck Ebbert
2006-02-09 8:55 ` Paul Jackson
2006-02-09 9:06 ` Andrew Morton
2006-02-09 9:11 ` Andrew Morton
2006-02-09 10:08 ` Heiko Carstens
2006-02-09 10:13 ` Andrew Morton
2006-02-09 10:23 ` Heiko Carstens
2006-02-09 10:31 ` Andrew Morton
2006-02-09 11:47 ` Heiko Carstens
2006-02-09 12:46 ` Eric Dumazet
2006-02-09 13:12 ` Heiko Carstens
2006-02-09 13:55 ` Eric Dumazet
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