Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753425AbZIIPIE (ORCPT ); Wed, 9 Sep 2009 11:08:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753450AbZIIPID (ORCPT ); Wed, 9 Sep 2009 11:08:03 -0400 Received: from mga03.intel.com ([143.182.124.21]:6662 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753425AbZIIPH4 (ORCPT ); Wed, 9 Sep 2009 11:07:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,271,1249282800"; d="scan'208";a="185728223" Message-Id: <20090909150601.159061863@intel.com> References: <20090909145141.293229693@intel.com> User-Agent: quilt/0.46-1 Date: Wed, 09 Sep 2009 22:51:48 +0800 From: Wu Fengguang To: Andrew Morton To: Jens Axboe CC: Dave Chinner CC: Chris Mason CC: Peter Zijlstra CC: Christoph Hellwig CC: jack@suse.cz CC: Artem Bityutskiy Cc: Wu Fengguang , LKML , Subject: [RFC][PATCH 7/7] writeback: balance_dirty_pages() shall write more than dirtied pages Content-Disposition: inline; filename=writeback-ratelimit.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2595 Lines: 69 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 2009-09-09 21:19:21.000000000 +0800 +++ linux/mm/page-writeback.c 2009-09-09 21:25:45.000000000 +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(); struct backing_dev_info *bdi = mapping->backing_dev_info; @@ -638,9 +638,10 @@ 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(); -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/