From: Rusty Russell <rusty@rustcorp.com.au>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
jeremy@goop.org, ebiederm@xmission.com, travis@sgi.com,
herbert@gondor.apana.org.au, xemul@openvz.org,
penberg@cs.helsinki.fi
Subject: Re: [patch 3/4] cpu alloc: The allocator
Date: Mon, 6 Oct 2008 07:10:43 +1000 [thread overview]
Message-ID: <200810060810.43511.rusty@rustcorp.com.au> (raw)
In-Reply-To: <48E614A0.60209@linux-foundation.org>
On Friday 03 October 2008 22:48:32 Christoph Lameter wrote:
> Andrew Morton wrote:
> > But I'd have though that it would be possible to only allocate the
> > storage for online CPUs. That would be a pretty significant win for
> > some system configurations?
>
> We have tried that but currently the kernel (core and in particular arch
> code) keeps state for all possible cpus in percpu segments. Would require
> more extensive cleanup of numerous arches to do.
It shouldn't be a big win, since possible ~= online for most systems. And
having all the per-cpu users register online and offline cpu callbacks is
error prone and a PITA.
Rusty.
WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
jeremy@goop.org, ebiederm@xmission.com, travis@sgi.com,
herbert@gondor.apana.org.au, xemul@openvz.org,
penberg@cs.helsinki.fi
Subject: Re: [patch 3/4] cpu alloc: The allocator
Date: Mon, 6 Oct 2008 07:10:43 +1000 [thread overview]
Message-ID: <200810060810.43511.rusty@rustcorp.com.au> (raw)
In-Reply-To: <48E614A0.60209@linux-foundation.org>
On Friday 03 October 2008 22:48:32 Christoph Lameter wrote:
> Andrew Morton wrote:
> > But I'd have though that it would be possible to only allocate the
> > storage for online CPUs. That would be a pretty significant win for
> > some system configurations?
>
> We have tried that but currently the kernel (core and in particular arch
> code) keeps state for all possible cpus in percpu segments. Would require
> more extensive cleanup of numerous arches to do.
It shouldn't be a big win, since possible ~= online for most systems. And
having all the per-cpu users register online and offline cpu callbacks is
error prone and a PITA.
Rusty.
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next prev parent reply other threads:[~2008-10-05 21:10 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-29 19:35 [patch 0/4] Cpu alloc V6: Replace percpu allocator in modules.c Christoph Lameter
2008-09-29 19:35 ` Christoph Lameter
2008-09-29 19:35 ` [patch 1/4] Make the per cpu reserve configurable Christoph Lameter
2008-09-29 19:35 ` Christoph Lameter
2008-09-29 19:35 ` [patch 2/4] percpu: Rename variables PERCPU_ENOUGH_ROOM -> PERCPU_AREA_SIZE Christoph Lameter
2008-09-29 19:35 ` Christoph Lameter
2008-09-29 19:35 ` [patch 3/4] cpu alloc: The allocator Christoph Lameter
2008-09-29 19:35 ` Christoph Lameter
2008-09-30 6:35 ` Pekka Enberg
2008-09-30 6:35 ` Pekka Enberg
2008-09-30 11:38 ` Christoph Lameter
2008-09-30 11:38 ` Christoph Lameter
2008-09-30 11:48 ` Pekka Enberg
2008-09-30 11:48 ` Pekka Enberg
2008-09-30 12:12 ` Christoph Lameter
2008-09-30 12:12 ` Christoph Lameter
2008-10-03 7:33 ` Andrew Morton
2008-10-03 7:33 ` Andrew Morton
2008-10-03 7:43 ` Pekka Enberg
2008-10-03 7:43 ` Pekka Enberg
2008-10-03 8:20 ` Andrew Morton
2008-10-03 8:20 ` Andrew Morton
2008-10-03 14:15 ` Christoph Lameter
2008-10-03 14:15 ` Christoph Lameter
2008-10-03 12:48 ` Christoph Lameter
2008-10-03 12:48 ` Christoph Lameter
2008-10-05 21:10 ` Rusty Russell [this message]
2008-10-05 21:10 ` Rusty Russell
2008-10-07 13:27 ` Christoph Lameter
2008-10-07 13:27 ` Christoph Lameter
2008-09-29 19:35 ` [patch 4/4] cpu alloc: Use cpu allocator instead of the builtin modules per cpu allocator Christoph Lameter
2008-09-29 19:35 ` Christoph Lameter
2008-09-30 22:28 ` Rusty Russell
2008-09-30 22:28 ` Rusty Russell
2008-09-30 22:27 ` [patch 0/4] Cpu alloc V6: Replace percpu allocator in modules.c Rusty Russell
2008-09-30 22:27 ` Rusty Russell
2008-10-07 23:34 ` Andrew Morton
2008-10-07 23:34 ` Andrew Morton
2008-10-08 15:10 ` Christoph Lameter
2008-10-08 15:10 ` Christoph Lameter
-- strict thread matches above, loose matches on Subject: below --
2008-09-19 14:58 [patch 0/4] Cpu alloc V5: " Christoph Lameter
2008-09-19 14:59 ` [patch 3/4] cpu alloc: The allocator Christoph Lameter
2008-09-19 14:59 ` Christoph Lameter
2008-09-19 15:23 ` KOSAKI Motohiro
2008-09-19 15:23 ` KOSAKI Motohiro
2008-09-19 16:27 ` Eric Dumazet
2008-09-19 16:27 ` Eric Dumazet
2008-09-19 16:49 ` Christoph Lameter
2008-09-19 16:49 ` Christoph Lameter
2008-09-19 17:00 ` Christoph Lameter
2008-09-19 17:00 ` Christoph Lameter
2008-09-19 20:32 ` Christoph Lameter
2008-09-19 20:32 ` Christoph Lameter
2008-09-18 23:36 [patch 0/4] Cpu alloc V4: Replace percpu allocator in modules.c Christoph Lameter
2008-09-18 23:36 ` [patch 3/4] cpu alloc: The allocator Christoph Lameter
2008-09-19 7:58 ` Pekka Enberg
2008-09-19 13:11 ` Christoph Lameter
2008-09-19 14:12 ` Pekka Enberg
2008-09-19 14:27 ` Christoph Lameter
2008-09-19 14:35 ` Pekka Enberg
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