From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754249Ab1HXGQJ (ORCPT ); Wed, 24 Aug 2011 02:16:09 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:57141 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750795Ab1HXGQH (ORCPT ); Wed, 24 Aug 2011 02:16:07 -0400 Date: Wed, 24 Aug 2011 02:16:02 -0400 From: Christoph Hellwig To: Dave Chinner Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, khlebnikov@openvz.org Subject: Re: [PATCH 01/13] fs: Use a common define for inode slab caches Message-ID: <20110824061602.GA24077@infradead.org> References: <1314089786-20535-1-git-send-email-david@fromorbit.com> <1314089786-20535-2-git-send-email-david@fromorbit.com> <20110823091307.GA21492@infradead.org> <20110823092041.GX3162@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110823092041.GX3162@dastard> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 23, 2011 at 07:20:41PM +1000, Dave Chinner wrote: > > Why do we keep the SLAB_HWCACHE_ALIGN flag for some filesystems? > > I didn't touch that one, mainly because I think that there are > different reasons for wanting cacheline alignment. e.g. a filesystem > aimed primarily at embedded systms with slow CPUs and little memory > doesn't want to waste memory on cacheline alignment.... A little grepping shows jffs2 is a counter example, because it exactly wants SLAB_HWCACHE_ALIGN to avoid issues with mtd dma. I'm fine with defering this for now, but the state of using SLAB_HWCACHE_ALIGN or not is just as much as mess as the rest of the inode slab flags was. I'd go as far as calling the whole existance of most slab flags an utter mess, but that is another fight.