Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934860AbZJNQEi (ORCPT ); Wed, 14 Oct 2009 12:04:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934838AbZJNQEg (ORCPT ); Wed, 14 Oct 2009 12:04:36 -0400 Received: from smtp2.ultrahosting.com ([74.213.174.253]:42142 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934850AbZJNQEf (ORCPT ); Wed, 14 Oct 2009 12:04:35 -0400 Date: Wed, 14 Oct 2009 11:56:29 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Pekka Enberg cc: Mel Gorman , David Rientjes , Tejun Heo , linux-kernel@vger.kernel.org, Mathieu Desnoyers , Zhang Yanmin Subject: Re: [this_cpu_xx V6 7/7] this_cpu: slub aggressive use of this_cpu operations in the hotpaths In-Reply-To: <4AD5F3F8.8080603@cs.helsinki.fi> Message-ID: References: <4AD4D8B6.6010700@cs.helsinki.fi> <20091014133457.GB5027@csn.ul.ie> <20091014154944.GD5027@csn.ul.ie> <4AD5F3F8.8080603@cs.helsinki.fi> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1121 Lines: 41 On Wed, 14 Oct 2009, Pekka Enberg wrote: > SLAB is able to queue lots of large objects but SLUB can't do that because it > has no queues. In SLUB, each CPU gets a page assigned to it that serves as a > "queue" but the size of the queue gets smaller as object size approaches page > size. > > We try to offset that with higher order allocations but IIRC we don't increase > the order linearly with object size and cap it to some reasonable maximum. You can test to see if larger pages have an influence by passing slub_max_order=6 or so on the kernel command line. You can force a large page use in slub by setting slub_min_order=3 f.e. Or you can force a mininum number of objecxcts in slub through f.e. slub_min_objects=50 slub_max_order=6 slub_min_objects=50 should result in pretty large slabs with lots of in page objects that allow slub to queue better. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/