From: Fengguang Wu <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
Greg Thelen <gthelen@google.com>, Ying Han <yinghan@google.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Minchan Kim <minchan.kim@gmail.com>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] mm: use global_dirty_limit in throttle_vm_writeout()
Date: Fri, 2 Mar 2012 14:14:51 +0800 [thread overview]
Message-ID: <20120302061451.GA6468@localhost> (raw)
When starting a memory hog task, a desktop box w/o swap is found to go
unresponsive for a long time. It's solely caused by lots of congestion
waits in throttle_vm_writeout():
gnome-system-mo-4201 553.073384: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1
gnome-system-mo-4201 553.073386: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000
gtali-4237 553.080377: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1
gtali-4237 553.080378: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000
Xorg-3483 553.103375: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1
Xorg-3483 553.103377: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000
The root cause is, the dirty threshold is knocked down a lot by the
memory hog task. Fixed by using global_dirty_limit which decreases
gradually on such events and can guarantee we stay above (the also
decreasing) nr_dirty in the progress of following down to the new
dirty threshold.
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
mm/page-writeback.c | 1 +
1 file changed, 1 insertion(+)
--- linux.orig/mm/page-writeback.c 2012-03-02 14:05:01.633763187 +0800
+++ linux/mm/page-writeback.c 2012-03-02 14:11:52.929772962 +0800
@@ -1472,6 +1472,7 @@ void throttle_vm_writeout(gfp_t gfp_mask
for ( ; ; ) {
global_dirty_limits(&background_thresh, &dirty_thresh);
+ dirty_thresh = hard_dirty_limit(dirty_thresh);
/*
* Boost the allowable dirty threshold a bit for page
--
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next reply other threads:[~2012-03-02 6:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-02 6:14 Fengguang Wu [this message]
2012-03-05 20:06 ` [PATCH] mm: use global_dirty_limit in throttle_vm_writeout() Rik van Riel
2012-03-19 7:37 ` Johannes Weiner
2012-03-21 0:43 ` Minchan Kim
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