[PATCH 0/3] sync livelock fixes

* [PATCH 0/3] sync livelock fixes
@ 2011-04-30 22:36 Wu Fengguang
  2011-04-30 22:36 ` [PATCH 1/3] writeback: introduce wbc.for_sync to cover the two sync stages Wu Fengguang
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Wu Fengguang @ 2011-04-30 22:36 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Jan Kara, Dave Chinner, Christoph Hellwig, Wu Fengguang, LKML,
	linux-fsdevel

Andrew,

I wrote a simple script to test sync livelock and this patchset is working as
expected:

	sync time: 2
	Dirty:             26492 kB
	Writeback:         30260 kB
	NFS_Unstable:          0 kB
	WritebackTmp:          0 kB
	sync NOT livelocked

In particular patch 2 fixes the sync livelock problem introduced by patch
"writeback: try more writeback as long as something was written".

Thanks,
Fengguang
---

#!/bin/sh

umount /dev/sda7
# mkfs.xfs -f /dev/sda7
mkfs.ext4 /dev/sda7
mount /dev/sda7 /fs

echo $((50<<20)) > /proc/sys/vm/dirty_bytes

pid=
for i in `seq 10`
do     
	dd if=/dev/zero of=/fs/zero-$i bs=1M count=1000 &
	pid="$pid $!"
done

sleep 1

tic=$(date +'%s')
sync
tac=$(date +'%s')

echo
echo sync time: $((tac-tic))
egrep '(Dirty|Writeback|NFS_Unstable)' /proc/meminfo

pidof dd > /dev/null && { kill -9 $pid; echo sync NOT livelocked; }

^ permalink raw reply	[flat|nested] 6+ messages in thread