From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Nick Piggin <npiggin@suse.de>
Cc: Christoph Lameter <cl@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Zhang Yanmin <yanmin_zhang@linux.intel.com>,
Matthew Wilcox <willy@linux.intel.com>,
Matt Mackall <mpm@selenic.com>, Mel Gorman <mel@csn.ul.ie>
Subject: Re: [RFC V2 SLEB 00/14] The Enhanced(hopefully) Slab Allocator
Date: Tue, 25 May 2010 12:53:43 +0300 [thread overview]
Message-ID: <AANLkTikXp5LlKLK1deKOQpciUFNugjlQah5QpNcImf39@mail.gmail.com> (raw)
In-Reply-To: <20100525093410.GH5087@laptop>
Hi Nick,
On Tue, May 25, 2010 at 12:34 PM, Nick Piggin <npiggin@suse.de> wrote:
>> The main selling point for SLUB was NUMA. Has the situation changed?
>
> Well one problem with SLAB was really just those alien caches. AFAIK
> they were added by Christoph Lameter (maybe wrong), and I didn't ever
> actually see much justification for them in the changelog. noaliencache
> can be and is used on bigger machines, and SLES and RHEL kernels are
> using SLAB on production NUMA systems up to thousands of CPU Altixes,
> and have been looking at working on SGI's UV, and hundreds of cores
> POWER7 etc.
Yes, Christoph and some other people introduced alien caches IIRC for
big iron SGI boxes. As for benchmarks, commit
e498be7dafd72fd68848c1eef1575aa7c5d658df ("Numa-aware slab allocator
V5") mentions AIM.
On Tue, May 25, 2010 at 12:34 PM, Nick Piggin <npiggin@suse.de> wrote:
> I have not seen NUMA benchmarks showing SLUB is significantly better.
> I haven't done much testing myself, mind you. But from indications, we
> could probably quite easily drop the alien caches setup and do like a
> simpler single remote freeing queue per CPU or something like that.
Commit 81819f0fc8285a2a5a921c019e3e3d7b6169d225 ("SLUB core") mentions
kernbench improvements.
Other than these two data points, I unfortunately don't have any as I
wasn't involved with merging of either of the patches. If other NUMA
people know better, please feel free to share the data.
On Tue, May 25, 2010 at 11:16 AM, Nick Piggin <npiggin@suse.de> wrote:
> I think we should: modernise SLAB code, add missing debug features,
> possibly turn off alien caches by default, chuck out SLUB, and then
> require that future changes have some reasonable bar set to justify
> them.
>
> I would not be at all against adding changes that transform SLAB to
> SLUB or SLEB or SLQB. That's how it really should be done in the
> first place.
Like I said, as a maintainer I'm happy to merge patches to modernize
SLAB but I still think you're underestimating the effort especially
considering the fact that we can't afford many performance regressions
there either. I guess trying to get rid of alien caches would be the
first logical step there.
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next prev parent reply other threads:[~2010-05-25 9:53 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-21 21:14 Christoph Lameter
2010-05-21 21:14 ` [RFC V2 SLEB 01/14] slab: Introduce a constant for a unspecified node Christoph Lameter
2010-06-07 21:44 ` David Rientjes
2010-06-07 22:30 ` Christoph Lameter
2010-06-08 5:41 ` Pekka Enberg
2010-06-08 6:20 ` David Rientjes
2010-06-08 6:34 ` Pekka Enberg
2010-06-08 23:35 ` David Rientjes
2010-06-09 5:55 ` Pekka Enberg
2010-06-09 6:20 ` David Rientjes
2010-05-21 21:14 ` [RFC V2 SLEB 02/14] SLUB: Constants need UL Christoph Lameter
2010-05-21 21:14 ` [RFC V2 SLEB 03/14] SLUB: Use kmem_cache flags to detect if Slab is in debugging mode Christoph Lameter
2010-06-08 3:57 ` David Rientjes
2010-05-21 21:14 ` [RFC V2 SLEB 04/14] SLUB: discard_slab_unlock Christoph Lameter
2010-05-21 21:14 ` [RFC V2 SLEB 05/14] SLUB: is_kmalloc_cache Christoph Lameter
2010-06-08 8:54 ` David Rientjes
2010-05-21 21:14 ` [RFC V2 SLEB 06/14] SLUB: Get rid of the kmalloc_node slab Christoph Lameter
2010-06-09 6:14 ` David Rientjes
2010-06-09 16:14 ` Christoph Lameter
2010-06-09 16:26 ` Pekka Enberg
2010-06-10 6:07 ` Pekka Enberg
2010-05-21 21:14 ` [RFC V2 SLEB 07/14] SLEB: The Enhanced Slab Allocator Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 08/14] SLEB: Resize cpu queue Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 09/14] SLED: Get rid of useless function Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 10/14] SLEB: Remove MAX_OBJS limitation Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 11/14] SLEB: Add per node cache (with a fixed size for now) Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 12/14] SLEB: Make the size of the shared cache configurable Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 13/14] SLEB: Enhanced NUMA support Christoph Lameter
2010-05-21 21:15 ` [RFC V2 SLEB 14/14] SLEB: Allocate off node objects from remote shared caches Christoph Lameter
2010-05-22 8:37 ` [RFC V2 SLEB 00/14] The Enhanced(hopefully) Slab Allocator Pekka Enberg
2010-05-24 7:03 ` Nick Piggin
2010-05-24 15:06 ` Christoph Lameter
2010-05-25 2:06 ` Nick Piggin
2010-05-25 6:55 ` Pekka Enberg
2010-05-25 7:07 ` Nick Piggin
2010-05-25 8:03 ` Pekka Enberg
2010-05-25 8:16 ` Nick Piggin
2010-05-25 9:19 ` Pekka Enberg
2010-05-25 9:34 ` Nick Piggin
2010-05-25 9:53 ` Pekka Enberg [this message]
2010-05-25 10:19 ` Nick Piggin
2010-05-25 10:45 ` Pekka Enberg
2010-05-25 11:06 ` Nick Piggin
2010-05-25 15:13 ` Linus Torvalds
2010-05-25 15:43 ` Nick Piggin
2010-05-25 17:02 ` Pekka Enberg
2010-05-25 17:19 ` Nick Piggin
2010-05-25 17:35 ` Pekka Enberg
2010-05-25 17:40 ` Nick Piggin
2010-05-25 10:07 ` David Rientjes
2010-05-25 10:02 ` David Rientjes
2010-05-25 10:47 ` Pekka Enberg
2010-05-25 19:57 ` David Rientjes
2010-05-25 14:13 ` Christoph Lameter
2010-05-25 14:34 ` Nick Piggin
2010-05-25 14:43 ` Nick Piggin
2010-05-25 14:48 ` Christoph Lameter
2010-05-25 15:11 ` Nick Piggin
2010-05-25 15:28 ` Christoph Lameter
2010-05-25 15:37 ` Nick Piggin
2010-05-27 14:24 ` Christoph Lameter
2010-05-27 14:37 ` Nick Piggin
2010-05-27 15:52 ` Christoph Lameter
2010-05-27 16:07 ` Nick Piggin
2010-05-27 16:57 ` Christoph Lameter
2010-05-28 8:39 ` Nick Piggin
2010-05-25 14:40 ` Nick Piggin
2010-05-25 14:48 ` Christoph Lameter
2010-05-25 15:12 ` Nick Piggin
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