From: Theodore Tso Subject: Re: ext4 not currently doing (much) multi-block allocation? Date: Sun, 15 Feb 2009 08:36:18 -0500 Message-ID: <20090215133618.GE10706@mini-me.lan> References: <20090215053206.GA4803@mini-me.lan> <20090215110528.GE22585@skywalker> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: "Aneesh Kumar K.V" Return-path: Received: from THUNK.ORG ([69.25.196.29]:41138 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753862AbZBONgh (ORCPT ); Sun, 15 Feb 2009 08:36:37 -0500 Content-Disposition: inline In-Reply-To: <20090215110528.GE22585@skywalker> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Feb 15, 2009 at 04:35:28PM +0530, Aneesh Kumar K.V wrote: > Here is how it works. During writepages we loop through the dirty pages > and build largest contiguous block extent (mpage_add_bh_to_extent). Then we call > mpage_da_map_blocks. mpage_da_map_blocks does the mutli block request. > Once we have the blocks allocated we map these blocks to the pages. And > then we writeback one page at a time using writepage callback. mpage_da_map_blocks() calls mpd->get_block, which is set to ext4_da_get_block_write(), which allocates a single block at a time (max_blocks is set to bh->b_size >> inode->i_blkbits). Put another way, where is the call to ext4_get_blocks_wrap() which does the multi-block request? I don't see it... - Ted