From: Badari Pulavarty Subject: Re: [PATCH] JBD slab cleanups Date: Mon, 17 Sep 2007 15:01:06 -0700 Message-ID: <1190066466.31220.5.camel@dyn9047017100.beaverton.ibm.com> References: <20070828190735.292638294@sgi.com> <1188432669.3799.35.camel@localhost.localdomain> <1188434857.3799.76.camel@localhost.localdomain> <1188605538.3837.51.camel@localhost.localdomain> <20070901183922.GA12907@infradead.org> <20070902152801.GA19962@infradead.org> <20070903134043.GB28962@infradead.org> <20070903193308.GA7771@infradead.org> <1189796027.3841.6.camel@localhost.localdomain> <1190057391.3845.22.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , Christoph Lameter , linux-fsdevel , ext4 development , lkml To: cmm@us.ibm.com Return-path: Received: from e33.co.us.ibm.com ([32.97.110.151]:32897 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758082AbXIQV6Q (ORCPT ); Mon, 17 Sep 2007 17:58:16 -0400 In-Reply-To: <1190057391.3845.22.camel@localhost.localdomain> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, 2007-09-17 at 12:29 -0700, Mingming Cao wrote: > On Fri, 2007-09-14 at 11:53 -0700, Mingming Cao wrote: > > jbd/jbd2: Replace slab allocations with page cache allocations > > > > From: Christoph Lameter > > > > JBD should not pass slab pages down to the block layer. > > Use page allocator pages instead. This will also prepare > > JBD for the large blocksize patchset. > > > > Currently memory allocation for committed_data(and frozen_buffer) for > bufferhead is done through jbd slab management, as Christoph Hellwig > pointed out that this is broken as jbd should not pass slab pages down > to IO layer. and suggested to use get_free_pages() directly. > > The problem with this patch, as Andreas Dilger pointed today in ext4 > interlock call, for 1k,2k block size ext2/3/4, get_free_pages() waste > 1/3-1/2 page space. > > What was the originally intention to set up slabs for committed_data(and > frozen_buffer) in JBD? Why not using kmalloc? > > Mingming Looks good. Small suggestion is to get rid of all kmalloc() usages and consistently use jbd_kmalloc() or jbd2_kmalloc(). Thanks, Badari