From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>, Wu Fengguang <fengguang.wu@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Andrea Righi <arighi@develer.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: linux-mm <linux-mm@kvack.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 16/27] writeback: smoothed global/bdi dirty pages
Date: Thu, 03 Mar 2011 14:45:21 +0800 [thread overview]
Message-ID: <20110303074950.704987840@intel.com> (raw)
In-Reply-To: 20110303064505.718671603@intel.com
[-- Attachment #1: writeback-smooth-dirty.patch --]
[-- Type: text/plain, Size: 3985 bytes --]
Maintain a smoothed version of dirty pages for use in the throttle
bandwidth calculations.
default_backing_dev_info.avg_dirty holds the smoothed global dirty
pages.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
include/linux/backing-dev.h | 2 +
mm/backing-dev.c | 3 +
mm/page-writeback.c | 62 ++++++++++++++++++++++++++++++++++
3 files changed, 67 insertions(+)
--- linux-next.orig/mm/page-writeback.c 2011-03-03 14:44:07.000000000 +0800
+++ linux-next/mm/page-writeback.c 2011-03-03 14:44:10.000000000 +0800
@@ -472,6 +472,64 @@ unsigned long bdi_dirty_limit(struct bac
return bdi_dirty;
}
+static void bdi_update_dirty_smooth(struct backing_dev_info *bdi,
+ unsigned long dirty)
+{
+ unsigned long avg = bdi->avg_dirty;
+ unsigned long old = bdi->old_dirty;
+
+ if (unlikely(!avg)) {
+ avg = dirty;
+ goto update;
+ }
+
+ /*
+ * dirty pages are departing upwards, follow up
+ */
+ if (avg < old && old <= dirty) {
+ avg += (old - avg) >> 3;
+ goto update;
+ }
+
+ /*
+ * dirty pages are departing downwards, follow down
+ */
+ if (avg > old && old >= dirty) {
+ avg -= (avg - old) >> 3;
+ goto update;
+ }
+
+ /*
+ * This can filter out one half unnecessary updates when bdi_dirty is
+ * fluctuating around the balance point, and is most effective on XFS,
+ * whose pattern is
+ * .
+ * [.] dirty [-] avg . .
+ * . .
+ * . . . . . .
+ * --------------------------------------- . .
+ * . . . . . .
+ * . . . . . .
+ * . . . . . .
+ * . . . . . .
+ * . . . .
+ * . . . . (flucuated)
+ * . . . .
+ * . . . .
+ *
+ * @avg will remain flat at the cost of being biased towards high. In
+ * practice the error tend to be much smaller: thanks to more coarse
+ * grained fluctuations, @avg becomes the real average number for the
+ * last two rising lines of @dirty.
+ */
+ goto out;
+
+update:
+ bdi->avg_dirty = avg;
+out:
+ bdi->old_dirty = dirty;
+}
+
static void __bdi_update_write_bandwidth(struct backing_dev_info *bdi,
unsigned long elapsed,
unsigned long written)
@@ -537,6 +595,10 @@ void bdi_update_bandwidth(struct backing
goto unlock;
__bdi_update_write_bandwidth(bdi, elapsed, written);
+ if (thresh) {
+ bdi_update_dirty_smooth(bdi, bdi_dirty);
+ bdi_update_dirty_smooth(&default_backing_dev_info, dirty);
+ }
snapshot:
bdi->written_stamp = written;
--- linux-next.orig/include/linux/backing-dev.h 2011-03-03 14:44:07.000000000 +0800
+++ linux-next/include/linux/backing-dev.h 2011-03-03 14:44:10.000000000 +0800
@@ -79,6 +79,8 @@ struct backing_dev_info {
unsigned long written_stamp;
unsigned long write_bandwidth;
unsigned long avg_bandwidth;
+ unsigned long avg_dirty;
+ unsigned long old_dirty;
struct prop_local_percpu completions;
int dirty_exceeded;
--- linux-next.orig/mm/backing-dev.c 2011-03-03 14:44:07.000000000 +0800
+++ linux-next/mm/backing-dev.c 2011-03-03 14:44:10.000000000 +0800
@@ -675,6 +675,9 @@ int bdi_init(struct backing_dev_info *bd
bdi->write_bandwidth = INIT_BW;
bdi->avg_bandwidth = INIT_BW;
+ bdi->avg_dirty = 0;
+ bdi->old_dirty = 0;
+
err = prop_local_init_percpu(&bdi->completions);
if (err) {
--
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next prev parent reply other threads:[~2011-03-03 6:45 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-03 6:45 [PATCH 00/27] IO-less dirty throttling v6 Wu Fengguang
2011-03-03 6:45 ` [PATCH 01/27] writeback: add bdi_dirty_limit() kernel-doc Wu Fengguang
2011-03-03 6:45 ` [PATCH 02/27] writeback: avoid duplicate balance_dirty_pages_ratelimited() calls Wu Fengguang
2011-03-03 6:45 ` [PATCH 03/27] writeback: skip balance_dirty_pages() for in-memory fs Wu Fengguang
2011-03-03 6:45 ` [PATCH 04/27] writeback: reduce per-bdi dirty threshold ramp up time Wu Fengguang
2011-03-03 6:45 ` [PATCH 05/27] btrfs: avoid duplicate balance_dirty_pages_ratelimited() calls Wu Fengguang
2011-03-03 6:45 ` [PATCH 06/27] btrfs: lower the dirty balance poll interval Wu Fengguang
2011-03-04 6:22 ` Dave Chinner
2011-03-04 7:57 ` Wu Fengguang
2011-03-03 6:45 ` [PATCH 07/27] btrfs: wait on too many nr_async_bios Wu Fengguang
2011-03-03 6:45 ` [PATCH 08/27] nfs: dirty livelock prevention is now done in VFS Wu Fengguang
2011-03-03 6:45 ` [PATCH 09/27] nfs: writeback pages wait queue Wu Fengguang
2011-03-03 16:07 ` Peter Zijlstra
2011-03-04 1:53 ` Wu Fengguang
2011-03-03 16:08 ` Peter Zijlstra
2011-03-04 2:01 ` Wu Fengguang
2011-03-04 9:10 ` Peter Zijlstra
2011-03-04 9:26 ` Peter Zijlstra
2011-03-04 14:38 ` Wu Fengguang
2011-03-04 14:41 ` Peter Zijlstra
2011-03-03 6:45 ` [PATCH 10/27] nfs: limit the commit size to reduce fluctuations Wu Fengguang
2011-03-03 6:45 ` [PATCH 11/27] nfs: limit the commit range Wu Fengguang
2011-03-03 6:45 ` [PATCH 12/27] nfs: lower writeback threshold proportionally to dirty threshold Wu Fengguang
2011-03-03 6:45 ` [PATCH 13/27] writeback: account per-bdi accumulated written pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 14/27] writeback: account per-bdi accumulated dirtied pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 15/27] writeback: bdi write bandwidth estimation Wu Fengguang
2011-03-03 6:45 ` Wu Fengguang [this message]
2011-03-03 6:45 ` [PATCH 17/27] writeback: smoothed dirty threshold and limit Wu Fengguang
2011-03-03 6:45 ` [PATCH 18/27] writeback: enforce 1/4 gap between the dirty/background thresholds Wu Fengguang
2011-03-03 6:45 ` [PATCH 19/27] writeback: dirty throttle bandwidth control Wu Fengguang
2011-03-07 21:34 ` Wu Fengguang
2011-03-29 21:08 ` Wu Fengguang
2011-03-03 6:45 ` [PATCH 20/27] writeback: IO-less balance_dirty_pages() Wu Fengguang
2011-03-03 6:45 ` [PATCH 21/27] writeback: show bdi write bandwidth in debugfs Wu Fengguang
2011-03-03 6:45 ` [PATCH 22/27] writeback: trace dirty_throttle_bandwidth Wu Fengguang
2011-03-03 6:45 ` [PATCH 23/27] writeback: trace balance_dirty_pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 24/27] writeback: trace global_dirty_state Wu Fengguang
2011-03-03 6:45 ` [PATCH 25/27] writeback: make nr_to_write a per-file limit Wu Fengguang
2011-03-03 6:45 ` [PATCH 26/27] writeback: scale IO chunk size up to device bandwidth Wu Fengguang
2011-03-03 6:45 ` [PATCH 27/27] writeback: trace writeback_single_inode Wu Fengguang
2011-03-03 20:12 ` [PATCH 00/27] IO-less dirty throttling v6 Vivek Goyal
2011-03-03 20:48 ` Vivek Goyal
2011-03-04 9:06 ` Wu Fengguang
2011-04-04 18:12 ` async write IO controllers Wu Fengguang
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