From: Andi Kleen <ak@muc.de>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Nathan Lynch <ntl@pobox.com>, Andrew Morton <akpm@osdl.org>,
Eric Dumazet <dada1@cosmosbay.com>,
riel@redhat.com, linux-kernel@vger.kernel.org, torvalds@osdl.org,
mingo@elte.hu, 76306.1226@compuserve.com, wli@holomorphy.com,
Paul Jackson <pj@sgi.com>
Subject: Re: [PATCH] percpu data: only iterate over possible CPUs
Date: 9 Feb 2006 18:37:26 +0100
Date: Thu, 9 Feb 2006 18:37:26 +0100 [thread overview]
Message-ID: <20060209173726.GA39278@muc.de> (raw)
In-Reply-To: <20060209161331.GE20554@osiris.boeblingen.de.ibm.com>
On Thu, Feb 09, 2006 at 05:13:31PM +0100, Heiko Carstens wrote:
> > > Presumably not all architectures are doing that.
> > powerpc/ppc64, for instance, determines the number of possible cpus
> > from information exported by firmware (and I'm mystified as to why
> > other platforms don't do this). So it's typical to have a kernel an a
> > pSeries partition with NR_CPUS=128, but cpu_possible_map = 0xff.
>
> Simply because there is no such interface on s390. The only thing we know
> for sure is that if we are running under z/VM the user is free to
> configure up to 63 additional virtual cpus on the fly...
x86-64 had the same problem, but we now require that you
boot with additional_cpus=... for how many you want. Default is 0
(used to be half available CPUs but that lead to confusion)
Also the firmware has a way now to give this information automatically.
You can of course make it default to 64, but it will cost you
several MB of memory in usually unused copies of per cpu data.
-Andi
next prev parent reply other threads:[~2006-02-09 17:37 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 [this message]
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
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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