From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932246Ab0LMGwf (ORCPT ); Mon, 13 Dec 2010 01:52:35 -0500 Received: from mga02.intel.com ([134.134.136.20]:4695 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755462Ab0LMGtr (ORCPT ); Mon, 13 Dec 2010 01:49:47 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.59,335,1288594800"; d="scan'208";a="583111656" Message-Id: <20101213064841.668000194@intel.com> User-Agent: quilt/0.48-1 Date: Mon, 13 Dec 2010 14:43:27 +0800 From: Wu Fengguang To: Andrew Morton CC: Jan Kara , Wu Fengguang CC: Christoph Hellwig CC: Trond Myklebust CC: Dave Chinner CC: "Theodore Ts'o" CC: Chris Mason CC: Peter Zijlstra CC: Mel Gorman CC: Rik van Riel CC: KOSAKI Motohiro CC: Greg Thelen CC: Minchan Kim Cc: linux-mm Cc: Cc: LKML Subject: [PATCH 38/47] btrfs: wait on too many nr_async_bios References: <20101213064249.648862451@intel.com> Content-Disposition: inline; filename=btrfs-nr_async_bios-wait.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tests show that btrfs is repeatedly moving _all_ PG_dirty pages into PG_writeback state. It's desirable to have some limit on the number of writeback pages. Signed-off-by: Wu Fengguang --- fs/btrfs/disk-io.c | 7 +++++++ 1 file changed, 7 insertions(+) before patch: http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/tests/3G/btrfs-1dd-1M-8p-2952M-2.6.37-rc5+-2010-12-08-21-30/vmstat-dirty-300.png after patch: http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/tests/3G/btrfs-1dd-1M-8p-2952M-2.6.37-rc5+-2010-12-08-21-14/vmstat-dirty-300.png --- linux-next.orig/fs/btrfs/disk-io.c 2010-12-09 12:21:03.000000000 +0800 +++ linux-next/fs/btrfs/disk-io.c 2010-12-09 12:25:00.000000000 +0800 @@ -590,6 +590,7 @@ int btrfs_wq_submit_bio(struct btrfs_fs_ extent_submit_bio_hook_t *submit_bio_done) { struct async_submit_bio *async; + int limit; async = kmalloc(sizeof(*async), GFP_NOFS); if (!async) @@ -617,6 +618,12 @@ int btrfs_wq_submit_bio(struct btrfs_fs_ btrfs_queue_worker(&fs_info->workers, &async->work); + limit = btrfs_async_submit_limit(fs_info); + + if (atomic_read(&fs_info->nr_async_bios) > limit) + wait_event(fs_info->async_submit_wait, + (atomic_read(&fs_info->nr_async_bios) < limit)); + while (atomic_read(&fs_info->async_submit_draining) && atomic_read(&fs_info->nr_async_submits)) { wait_event(fs_info->async_submit_wait,