From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422908AbXCGRUB (ORCPT ); Wed, 7 Mar 2007 12:20:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422905AbXCGRT5 (ORCPT ); Wed, 7 Mar 2007 12:19:57 -0500 Received: from verein.lst.de ([213.95.11.210]:52909 "EHLO mail.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422940AbXCGRTI (ORCPT ); Wed, 7 Mar 2007 12:19:08 -0500 Date: Wed, 7 Mar 2007 18:15:47 +0100 From: Christoph Hellwig To: Michael Nishimoto Cc: Christoph Hellwig , xfs@oss.sgi.com, ecashin@coraid.com, akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] xfs: stop using kmalloc in xfs_buf_get_noaddr Message-ID: <20070307171547.GA22641@lst.de> References: <20070307101324.GC30587@lst.de> <45EEF0B5.40905@agami.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45EEF0B5.40905@agami.com> User-Agent: Mutt/1.3.28i X-Spam-Score: -0.001 () BAYES_44 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 07, 2007 at 09:04:53AM -0800, Michael Nishimoto wrote: > Incore log buffers are not always a power of two of the page size. > In particular, when xfs is running over software raid devices, the > log buffers are allocated to match the size of a stripe. > > However, they are always a multiple of PAGE_SIZE, so we are still safe. It's not actually about beeing safe - any allocation is still safe with this patch. The issue is just that we waste memory because we round up allocations to the next page size. The power of two bit is actually wrong in this mail, it was about another optimization I have that needs some more testing first.