From: Wu Fengguang <fengguang.wu@intel.com>
To: linux-mm <linux-mm@kvack.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Richard Kennedy <richard@rsk.demon.co.uk>,
"Martin J. Bligh" <mbligh@google.com>,
Wu Fengguang <fengguang.wu@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Theodore Ts'o <tytso@mit.edu>, Dave Chinner <david@fromorbit.com>,
Jan Kara <jack@suse.cz>, Mel Gorman <mel@csn.ul.ie>,
Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Chris Mason <chris.mason@oracle.com>,
Christoph Hellwig <hch@lst.de>, Li Shaohua <shaohua.li@intel.com>
Subject: [PATCH 13/17] writeback: reduce per-bdi dirty threshold ramp up time
Date: Sun, 12 Sep 2010 23:49:58 +0800 [thread overview]
Message-ID: <20100912155204.602761236@intel.com> (raw)
In-Reply-To: 20100912154945.758129106@intel.com
[-- Attachment #1: writeback-speedup-per-bdi-threshold-ramp-up.patch --]
[-- Type: text/plain, Size: 1780 bytes --]
Reduce the dampening for the control system, yielding faster
convergence.
Currently it converges at a snail's pace for slow devices (in order of
minutes). For really fast storage, the convergence speed should be fine.
It makes sense to make it reasonably fast for typical desktops.
After patch, it converges in ~10 seconds for 60MB/s writes and 4GB mem.
So expect ~1s for a fast 600MB/s storage under 4GB mem, or ~4s under
16GB mem, which looks good.
$ while true; do grep BdiDirtyThresh /debug/bdi/8:0/stats; sleep 1; done
BdiDirtyThresh: 0 kB
BdiDirtyThresh: 118748 kB
BdiDirtyThresh: 214280 kB
BdiDirtyThresh: 303868 kB
BdiDirtyThresh: 376528 kB
BdiDirtyThresh: 411180 kB
BdiDirtyThresh: 448636 kB
BdiDirtyThresh: 472260 kB
BdiDirtyThresh: 490924 kB
BdiDirtyThresh: 499596 kB
BdiDirtyThresh: 507068 kB
...
DirtyThresh: 530392 kB
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Richard Kennedy <richard@rsk.demon.co.uk>
CC: Martin J. Bligh <mbligh@google.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
mm/page-writeback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- linux-next.orig/mm/page-writeback.c 2010-08-30 10:24:00.000000000 +0800
+++ linux-next/mm/page-writeback.c 2010-08-30 10:27:10.000000000 +0800
@@ -131,7 +131,7 @@ static int calc_period_shift(void)
else
dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) /
100;
- return 2 + ilog2(dirty_total - 1);
+ return ilog2(dirty_total - 1) - 1;
}
/*
--
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next prev parent reply other threads:[~2010-09-12 15:55 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-12 15:49 [PATCH 00/17] [RFC] soft and dynamic dirty throttling limits Wu Fengguang
2010-09-12 15:49 ` [PATCH 01/17] writeback: remove the internal 5% low bound on dirty_ratio Wu Fengguang
2010-09-13 9:23 ` Johannes Weiner
2010-09-13 9:51 ` Mel Gorman
2010-09-13 9:57 ` Wu Fengguang
2010-09-13 10:10 ` Mel Gorman
2010-09-12 15:49 ` [PATCH 02/17] writeback: IO-less balance_dirty_pages() Wu Fengguang
2010-09-13 8:45 ` Dave Chinner
2010-09-13 11:38 ` Wu Fengguang
2010-09-12 15:49 ` [PATCH 03/17] writeback: per-task rate limit to balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 04/17] writeback: quit throttling when bdi dirty/writeback pages go down Wu Fengguang
2010-09-12 15:49 ` [PATCH 05/17] writeback: quit throttling when signal pending Wu Fengguang
2010-09-12 20:46 ` Neil Brown
2010-09-13 1:55 ` Wu Fengguang
2010-09-13 3:21 ` Neil Brown
2010-09-13 3:48 ` Wu Fengguang
2010-09-14 8:23 ` KOSAKI Motohiro
2010-09-14 8:33 ` Wu Fengguang
2010-09-14 8:44 ` KOSAKI Motohiro
2010-09-14 9:17 ` Wu Fengguang
2010-09-14 9:25 ` KOSAKI Motohiro
2010-09-12 15:49 ` [PATCH 06/17] writeback: move task dirty fraction to balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 07/17] writeback: add trace event for balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 08/17] writeback: account per-bdi accumulated written pages Wu Fengguang
2010-09-12 15:59 ` Wu Fengguang
2010-09-14 8:32 ` KOSAKI Motohiro
2010-09-12 15:49 ` [PATCH 09/17] writeback: bdi write bandwidth estimation Wu Fengguang
2010-09-12 15:49 ` [PATCH 10/17] writeback: show bdi write bandwidth in debugfs Wu Fengguang
2010-09-12 15:49 ` [PATCH 11/17] writeback: make nr_to_write a per-file limit Wu Fengguang
2010-09-12 15:49 ` [PATCH 12/17] writeback: scale IO chunk size up to device bandwidth Wu Fengguang
2010-09-12 15:49 ` Wu Fengguang [this message]
2010-09-12 16:15 ` [PATCH 13/17] writeback: reduce per-bdi dirty threshold ramp up time Wu Fengguang
2010-09-12 15:49 ` [PATCH 14/17] vmscan: add scan_control.priority Wu Fengguang
2010-09-12 15:50 ` [PATCH 15/17] mm: lower soft dirty limits on memory pressure Wu Fengguang
2010-09-13 9:40 ` Wu Fengguang
2010-09-12 15:50 ` [PATCH 16/17] mm: create /vm/dirty_pressure in debugfs Wu Fengguang
2010-09-12 15:50 ` [PATCH 17/17] writeback: consolidate balance_dirty_pages() variable names Wu Fengguang
2010-10-12 14:17 ` [PATCH 00/17] [RFC] soft and dynamic dirty throttling limits Christoph Hellwig
2010-10-13 3:07 ` Dave Chinner
2010-10-13 3:23 ` Wu Fengguang
2010-10-13 8:26 ` Wu Fengguang
2010-10-13 9:26 ` Dave Chinner
2010-11-01 6:24 ` Dave Chinner
2010-11-04 3:41 ` Wu Fengguang
2010-11-04 12:48 ` Dave Chinner
2010-11-04 13:12 ` Christoph Hellwig
2010-11-05 14:56 ` Wu Fengguang
2010-11-06 10:42 ` Dave Chinner
2010-10-14 13:12 ` Wu Fengguang
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