From: Christoph Lameter <clameter@sgi.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: matthew@wil.cx, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
penberg@cs.helsinki.fi,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
linux-arch@vger.kernel.org
Subject: Re: [patch 08/10] SLUB: Optional fast path using cmpxchg_local
Date: Tue, 30 Oct 2007 11:58:08 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0710301155240.12746@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <20071030114933.904a4cf8.akpm@linux-foundation.org>
On Tue, 30 Oct 2007, Andrew Morton wrote:
> Let's cc linux-arch: presumably other architectures can implement cpu-local
> cmpxchg and would see some benefit from doing so.
Matheiu had a whole series of cmpxchg_local patches. Ccing him too. I
think he has some numbers for other architectures.
> The semantics are "atomic wrt interrutps on this cpu, not atomic wrt other
> cpus", yes?
Right.
> Do you have a feel for how useful it would be for arch maintainers to implement
> this? IOW, is it worth their time?
That depends on the efficiency of a cmpxchg_local vs. the interrupt
enable/ disable sequence on a particular arch. On x86 this yields about
50% so it doubles the speed of the fastpath. On other architectures the
cmpxchg is so slow that it is not worth it (ia64 f.e.)
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next prev parent reply other threads:[~2007-10-30 18:58 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-28 3:31 [patch 00/10] SLUB: SMP regression tests on Dual Xeon E5345 (8p) and new performance patches Christoph Lameter
2007-10-28 3:31 ` [patch 01/10] SLUB: Consolidate add_partial and add_partial_tail to one function Christoph Lameter
2007-10-28 13:07 ` Pekka J Enberg
2007-10-28 3:31 ` [patch 02/10] SLUB: Noinline some functions to avoid them being folded into alloc/free Christoph Lameter
2007-10-28 13:08 ` Pekka J Enberg
2007-10-29 23:25 ` Matt Mackall
2007-10-28 3:31 ` [patch 03/10] SLUB: Move kmem_cache_node determination into add_full and add_partial Christoph Lameter
2007-10-28 13:09 ` Pekka J Enberg
2007-10-28 3:32 ` [patch 04/10] SLUB: Avoid checking for a valid object before zeroing on the fast path Christoph Lameter
2007-10-28 13:10 ` Pekka J Enberg
2007-10-28 3:32 ` [patch 05/10] SLUB: __slab_alloc() exit path consolidation Christoph Lameter
2007-10-28 13:11 ` Pekka J Enberg
2007-10-28 3:32 ` [patch 06/10] SLUB: Provide unique end marker for each slab Christoph Lameter
2007-10-28 3:32 ` [patch 07/10] SLUB: Avoid referencing kmem_cache structure in __slab_alloc Christoph Lameter
2007-10-28 13:12 ` Pekka J Enberg
2007-10-30 18:38 ` Andrew Morton
2007-10-28 3:32 ` [patch 08/10] SLUB: Optional fast path using cmpxchg_local Christoph Lameter
2007-10-28 13:05 ` Pekka J Enberg
2007-10-29 2:59 ` Christoph Lameter
2007-10-29 3:34 ` Christoph Lameter
2007-10-30 18:30 ` Andrew Morton
2007-10-30 18:49 ` Andrew Morton
2007-10-30 18:58 ` Christoph Lameter [this message]
2007-10-30 19:12 ` Mathieu Desnoyers
2007-10-31 1:52 ` [PATCH] local_t Documentation update 2 Mathieu Desnoyers
2007-10-31 2:28 ` [patch 08/10] SLUB: Optional fast path using cmpxchg_local Mathieu Desnoyers
2007-10-28 3:32 ` [patch 09/10] SLUB: Do our own locking via slab_lock and slab_unlock Christoph Lameter
2007-10-28 15:10 ` Pekka J Enberg
2007-10-28 15:14 ` Pekka J Enberg
2007-10-29 3:03 ` Christoph Lameter
2007-10-29 6:30 ` Pekka Enberg
2007-10-30 4:50 ` Nick Piggin
2007-10-30 18:32 ` Christoph Lameter
2007-10-31 1:17 ` Nick Piggin
2007-10-28 3:32 ` [patch 10/10] SLUB: Restructure slab alloc Christoph Lameter
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