From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751291Ab1JCXMw (ORCPT ); Mon, 3 Oct 2011 19:12:52 -0400 Received: from out3.smtp.messagingengine.com ([66.111.4.27]:56120 "EHLO out3.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750745Ab1JCXMv (ORCPT ); Mon, 3 Oct 2011 19:12:51 -0400 X-Sasl-enc: m00n+AOIXWzIORQ7JbJ1/W/zbc4L8V0Mxt1dd2CRvQOj 1317683353 Date: Mon, 3 Oct 2011 16:06:32 -0700 From: Greg KH To: Seth Jennings Cc: gregkh@suse.de, cascardo@holoscopio.com, dan.magenheimer@oracle.com, rdunlap@xenotime.net, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] staging: zcache: reduce tmem bucket lock contention Message-ID: <20111003230632.GA12719@kroah.com> References: <1317306746-27072-1-git-send-email-sjenning@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317306746-27072-1-git-send-email-sjenning@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 29, 2011 at 09:32:26AM -0500, Seth Jennings wrote: > tmem uses hash buckets each with their own rbtree and lock to > quickly lookup tmem objects. tmem has TMEM_HASH_BUCKETS (256) > buckets per pool. However, because of the way the tmem_oid is > generated for frontswap pages, only 16 unique tmem_oids are being > generated, resulting in only 16 of the 256 buckets being used. > This cause high lock contention for the per bucket locks. > > This patch changes SWIZ_BITS to include more bits of the offset. > The result is that all 256 hash buckets are potentially used resulting in a > 95% drop in hash bucket lock contention. This patch is somehow corrupted and can't be applied, care to resend it with Dan's acked-by so that I can apply it? thanks, greg k-h