From: Nick Piggin <npiggin@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>,
netdev@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
yanmin_zhang@linux.intel.com, David Miller <davem@davemloft.net>,
Eric Dumazet <dada1@cosmosbay.com>
Subject: Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment
Date: Thu, 6 Mar 2008 03:49:04 +0100 [thread overview]
Message-ID: <20080306024904.GA27150@wotan.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0803051254570.30742@schroedinger.engr.sgi.com>
On Wed, Mar 05, 2008 at 12:56:33PM -0800, Christoph Lameter wrote:
> On Wed, 5 Mar 2008, Nick Piggin wrote:
>
> > It started out as a SLUB regression that was exposing poor code in the
> > percpu allocator due to different SLUB kmalloc alignments. That prompted
>
> That was due to SLUB's support for smaller allocation sizes. AFAICT has
> nothing to do with alignment.
The smaller sizes meant objects were less often aligned on cacheline
boundaries.
> > The SMP flag was just an RFC. I think some people (like Christoph) were
> > being confused about the HWCACHE_ALIGN flag being for avoiding false
> > sharing on SMP systems. It would actually be also generally useful to
> > have the SMP flag (eg. see the sites I added it to in patch #3).
>
> Hmmm. We could define a global constant for that? Determine it on bootup
> and then pass it as an alignment parameter?
We could, but I'd rather just use the flag.
next prev parent reply other threads:[~2008-03-06 2:49 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-03 9:34 [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment Nick Piggin
2008-03-03 9:35 ` [rfc][patch 2/3] slab: introduce SMP alignment Nick Piggin
2008-03-03 19:06 ` Christoph Lameter
2008-03-03 20:03 ` Nick Piggin
2008-03-03 20:09 ` Christoph Lameter
2008-03-03 20:12 ` Nick Piggin
2008-03-03 20:17 ` Christoph Lameter
2008-03-03 20:24 ` Nick Piggin
2008-03-03 20:41 ` Pekka Enberg
2008-03-03 21:23 ` Christoph Lameter
2008-03-03 21:31 ` Christoph Lameter
2008-03-05 0:16 ` Nick Piggin
2008-03-07 4:37 ` Nick Piggin
2008-03-07 5:11 ` Christoph Lameter
2008-03-07 5:19 ` Nick Piggin
2008-03-07 5:26 ` Christoph Lameter
2008-03-07 5:37 ` Nick Piggin
2008-03-11 7:13 ` Nick Piggin
2008-03-12 6:21 ` Christoph Lameter
2008-03-03 9:36 ` [rfc][patch 3/3] use SLAB_ALIGN_SMP Nick Piggin
2008-03-03 9:53 ` Eric Dumazet
2008-03-03 12:41 ` Nick Piggin
2008-03-03 13:00 ` Eric Dumazet
2008-03-03 13:46 ` Nick Piggin
2008-03-03 13:53 ` Pekka Enberg
2008-03-03 14:15 ` Eric Dumazet
2008-03-03 19:10 ` Christoph Lameter
2008-03-03 19:09 ` Christoph Lameter
2008-03-03 20:10 ` Nick Piggin
2008-03-03 20:12 ` Christoph Lameter
2008-03-03 20:18 ` Nick Piggin
2008-03-03 21:14 ` Christoph Lameter
2008-03-03 9:44 ` [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment Pekka Enberg
2008-03-03 12:28 ` Nick Piggin
2008-03-03 19:08 ` Christoph Lameter
2008-03-03 20:06 ` Nick Piggin
2008-03-03 20:10 ` Christoph Lameter
2008-03-03 20:17 ` Nick Piggin
2008-03-03 21:16 ` Christoph Lameter
2008-03-03 21:30 ` Pekka Enberg
2008-03-03 21:32 ` Christoph Lameter
2008-03-03 21:35 ` Pekka Enberg
2008-03-05 0:28 ` Nick Piggin
2008-03-05 20:56 ` Christoph Lameter
2008-03-06 2:49 ` Nick Piggin [this message]
2008-03-06 22:53 ` Christoph Lameter
2008-03-07 2:04 ` Nick Piggin
2008-03-07 2:20 ` Christoph Lameter
2008-03-07 2:25 ` Nick Piggin
2008-03-07 2:27 ` Christoph Lameter
2008-03-07 2:33 ` Nick Piggin
2008-03-07 2:33 ` Christoph Lameter
2008-03-07 5:23 ` Nick Piggin
2008-03-05 0:08 ` Nick Piggin
2008-03-05 0:06 ` Nick Piggin
2008-03-05 0:10 ` David Miller
2008-03-05 21:06 ` Christoph Lameter
2008-03-06 2:57 ` Nick Piggin
2008-03-06 22:56 ` Christoph Lameter
2008-03-07 2:23 ` Nick Piggin
2008-03-07 2:26 ` Christoph Lameter
2008-03-07 2:32 ` Nick Piggin
2008-03-07 2:54 ` Christoph Lameter
2008-03-07 3:10 ` Nick Piggin
2008-03-07 3:18 ` Christoph Lameter
2008-03-07 3:22 ` Nick Piggin
2008-03-07 3:58 ` Christoph Lameter
2008-03-07 4:05 ` Nick Piggin
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