From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751981AbZIWMnq (ORCPT ); Wed, 23 Sep 2009 08:43:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750977AbZIWMnp (ORCPT ); Wed, 23 Sep 2009 08:43:45 -0400 Received: from mga03.intel.com ([143.182.124.21]:41517 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751230AbZIWMnj (ORCPT ); Wed, 23 Sep 2009 08:43:39 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,438,1249282800"; d="scan'208";a="190735397" Message-Id: <20090923124027.456325340@intel.com> User-Agent: quilt/0.48-1 Date: Wed, 23 Sep 2009 20:33:39 +0800 From: Wu Fengguang To: Andrew Morton To: Jens Axboe CC: Jan Kara , Wu Fengguang CC: "Theodore Ts'o" CC: Dave Chinner CC: Chris Mason CC: Christoph Hellwig CC: Peter Zijlstra CC: Cc: LKML Subject: [PATCH 1/6] writeback: balance_dirty_pages() shall write more than dirtied pages References: <20090923123337.990689487@intel.com> Content-Disposition: inline; filename=writeback-ratelimit.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some filesystem may choose to write much more than ratelimit_pages before calling balance_dirty_pages_ratelimited_nr(). So it is safer to determine number to write based on real number of dirtied pages. The increased write_chunk may make the dirtier more bumpy. This is filesystem writers' duty not to dirty too much at a time without checking the ratelimit. Signed-off-by: Wu Fengguang --- mm/page-writeback.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- linux.orig/mm/page-writeback.c 2009-09-23 16:31:46.000000000 +0800 +++ linux/mm/page-writeback.c 2009-09-23 16:33:19.000000000 +0800 @@ -44,12 +44,12 @@ static long ratelimit_pages = 32; /* * When balance_dirty_pages decides that the caller needs to perform some * non-background writeback, this is how many pages it will attempt to write. - * It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably + * It should be somewhat larger than dirtied pages to ensure that reasonably * large amounts of I/O are submitted. */ -static inline long sync_writeback_pages(void) +static inline long sync_writeback_pages(unsigned long dirtied) { - return ratelimit_pages + ratelimit_pages / 2; + return dirtied + dirtied / 2; } /* The following parameters are exported via /proc/sys/vm */ @@ -476,7 +476,8 @@ get_dirty_limits(unsigned long *pbackgro * If we're over `background_thresh' then pdflush is woken to perform some * writeout. */ -static void balance_dirty_pages(struct address_space *mapping) +static void balance_dirty_pages(struct address_space *mapping, + unsigned long write_chunk) { long nr_reclaimable, bdi_nr_reclaimable; long nr_writeback, bdi_nr_writeback; @@ -484,7 +485,6 @@ static void balance_dirty_pages(struct a unsigned long dirty_thresh; unsigned long bdi_thresh; unsigned long pages_written = 0; - unsigned long write_chunk = sync_writeback_pages(); unsigned long pause = 1; struct backing_dev_info *bdi = mapping->backing_dev_info; @@ -640,9 +640,10 @@ void balance_dirty_pages_ratelimited_nr( p = &__get_cpu_var(bdp_ratelimits); *p += nr_pages_dirtied; if (unlikely(*p >= ratelimit)) { + ratelimit = sync_writeback_pages(*p); *p = 0; preempt_enable(); - balance_dirty_pages(mapping); + balance_dirty_pages(mapping, ratelimit); return; } preempt_enable();