From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751877AbXHNHDt (ORCPT ); Tue, 14 Aug 2007 03:03:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750796AbXHNHDg (ORCPT ); Tue, 14 Aug 2007 03:03:36 -0400 Received: from mga09.intel.com ([134.134.136.24]:33565 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750747AbXHNHDe (ORCPT ); Tue, 14 Aug 2007 03:03:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.19,258,1183359600"; d="scan'208";a="117252410" Date: Mon, 13 Aug 2007 23:56:57 -0700 From: "Siddha, Suresh B" To: Christoph Lameter Cc: "Siddha, Suresh B" , lethal@linux-sh.org, penberg@cs.helsinki.fi, linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: Re: [patch] slab: revert "slab: fix alien cache handling" Message-ID: <20070814065657.GF10033@linux-os.sc.intel.com> References: <20070813175824.GB12874@linux-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 13, 2007 at 01:58:48PM -0700, Christoph Lameter wrote: > On Mon, 13 Aug 2007, Siddha, Suresh B wrote: > > > Can we revert git commit 3cdc0ed0cea50ea08dd146c1bbc82b1bcc2e1b80 ? > > Only if you find another way to fix the bug that is addressed there. Does the appended version fix both the issues? Name alien in cache_free_alien is confusing, as the function does two things. free through alien caches or direct remote free.. thanks, suresh --- Skip calling cache_free_alien() when the platform is not numa capable. This will avoid cache misses that happen while accessing slabp (which is per page memory reference) to get nodeid. Instead use a global variable to skip the call, which is mostly likely to be present in the cache. This gives a 0.8% performance boost with the database oltp workload on a quad-core SMP platform and by any means the number is not small :) Signed-off-by: Suresh Siddha --- diff --git a/mm/slab.c b/mm/slab.c index a684778..6f6abef 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -883,6 +883,7 @@ static void __slab_error(const char *function, struct kmem_cache *cachep, */ static int use_alien_caches __read_mostly = 1; +static int numa_platform __read_mostly = 1; static int __init noaliencache_setup(char *s) { use_alien_caches = 0; @@ -1399,8 +1400,10 @@ void __init kmem_cache_init(void) int order; int node; - if (num_possible_nodes() == 1) + if (num_possible_nodes() == 1) { use_alien_caches = 0; + numa_platform = 0; + } for (i = 0; i < NUM_INIT_LISTS; i++) { kmem_list3_init(&initkmem_list3[i]); @@ -3558,7 +3561,14 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp) check_irq_off(); objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0)); - if (cache_free_alien(cachep, objp)) + /* + * Skip calling cache_free_alien() when the platform is not numa. + * This will avoid cache misses that happen while accessing slabp (which + * is per page memory reference) to get nodeid. Instead use a global + * variable to skip the call, which is mostly likely to be present in + * the cache. + */ + if (numa_platform && cache_free_alien(cachep, objp)) return; if (likely(ac->avail < ac->limit)) {