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From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	linux-next@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] percpu: use percpu allocator on UP too
Date: Sat, 04 Sep 2010 09:54:36 +0300	[thread overview]
Message-ID: <4C81ED2C.6000304@cs.helsinki.fi> (raw)
In-Reply-To: <4C8121BC.7040609@kernel.org>

On 3.9.2010 19.26, Tejun Heo wrote:
> On UP, percpu allocations were redirected to kmalloc.  This has the
> following problems.
>
> * For certain amount of allocations (determined by
>    PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu
>    allocator can be used before the usual kernel memory allocator is
>    brought online.  On SMP, this is used to initialize the kernel
>    memory allocator.
>
> * percpu allocator honors alignment upto PAGE_SIZE but kmalloc()
>    doesn't.  For example, workqueue makes use of larger alignments for
>    cpu_workqueues.
>
> Currently, users of percpu allocators need to handle UP differently,
> which is somewhat fragile and ugly.  Other than small amount of
> memory, there isn't much to lose by enabling percpu allocator on UP.
> It can simply use kernel memory based chunk allocation which was added
> for SMP archs w/o MMUs.
>
> This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and
> makes UP build use percpu-km.  As percpu addresses and kernel
> addresses are always identity mapped and static percpu variables don't
> need any special treatment, nothing is arch dependent and mm/percpu.c
> implements generic setup_per_cpu_areas() for UP.
>
> Signed-off-by: Tejun Heo<tj@kernel.org>
> Cc: Christoph Lameter<cl@linux-foundation.org>
> Cc: Pekka Enberg<penberg@cs.helsinki.fi>

Acked-by: Pekka Enberg <penberg@kernel.org>

Is this going into some public append-only branch I could cherry-pick 
the changeset from to my 'slub/cleanups' branch?

			Pekka

  parent reply	other threads:[~2010-09-04  6:54 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-24  2:07 linux-next: build failure after merge of the final tree (slab tree related) Stephen Rothwell
2010-08-24 17:41 ` Pekka Enberg
2010-08-24 17:59   ` Christoph Lameter
2010-08-24 18:32     ` Pekka Enberg
2010-08-24 18:53       ` Christoph Lameter
2010-08-25  8:18         ` Tejun Heo
2010-08-25  8:57           ` Pekka Enberg
2010-08-25 13:50             ` Christoph Lameter
2010-08-26  8:35               ` Tejun Heo
2010-09-03 16:25                 ` [PATCH 1/3] vmalloc: pcpu_get/free_vm_areas() aren't needed on UP Tejun Heo
2010-09-03 17:16                   ` Christoph Lameter
2010-09-03 16:26                 ` [PATCH 2/3] percpu: reduce PCPU_MIN_UNIT_SIZE to 32k Tejun Heo
2010-09-03 17:18                   ` Christoph Lameter
2010-09-03 16:26                 ` [PATCH 3/3] percpu: use percpu allocator on UP too Tejun Heo
2010-09-03 18:43                   ` Christoph Lameter
2010-09-04  6:54                   ` Pekka Enberg [this message]
2010-09-04  9:47                     ` Tejun Heo
2010-09-08  9:17                       ` Tejun Heo
2010-09-10 14:59                         ` Tejun Heo
2010-09-18 17:47                           ` Pekka Enberg
2010-09-03 16:27                 ` [PATCH RESEND 1/3] vmalloc: pcpu_get/free_vm_areas() aren't needed on UP Tejun Heo
2010-08-25 20:12           ` linux-next: build failure after merge of the final tree (slab tree related) Christoph Lameter
2010-08-25 21:37             ` Christoph Lameter
2010-08-25  0:13   ` Stephen Rothwell
2010-08-25  4:46     ` Pekka Enberg
2010-08-25 14:07       ` Christoph Lameter
2010-08-26  0:01         ` David Rientjes
2010-08-26  1:35           ` Christoph Lameter
2010-08-26  3:16             ` David Rientjes
2010-08-26 14:41               ` Christoph Lameter
2010-08-26 18:16                 ` Pekka Enberg

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