linux-kernel - Re: regression: 100% io-wait with 2.6.24-rcX

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Date:	Sun, 13 Jan 2008 14:44:34 +0800
From:	Fengguang Wu <wfg@...l.ustc.edu.cn>
To:	Joerg Platte <jplatte@...sa.net>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: regression: 100% io-wait with 2.6.24-rcX

On Sun, Jan 13, 2008 at 12:32:30AM +0100, Joerg Platte wrote:
> Am Freitag, 11. Januar 2008 schrieb Fengguang Wu:
> > On Thu, Jan 10, 2008 at 11:03:05AM +0100, Joerg Platte wrote:
> > > Am Donnerstag, 10. Januar 2008 schrieb Fengguang Wu:
> > > > > problem, because the iowait problem disappeared today after the
> > > > > regular Debian update. I'll try to install the old package versions
> > > > > to make it show up again. Maybe that helps to debug it.
> > > >
> > > > Thank you. I'm running sid, ext2 as rootfs now ;-)
> > >
> > > The error is back and I'm getting thousands of messages like this with
> > > the patched kernel:
> > >
> > > mm/page-writeback.c 668 wb_kupdate: pdflush(146) 21115 global 3936 0 0 wc
> > > _M > tw 1024 sk 0 requeue_io 301: inode 81441 size 0 at 08:07(sda7)
> > > mm/page-writeback.c 668 wb_kupdate: pdflush(147) 17451 global 3936 0 0 wc
> > > _M > tw 1024 sk 2 requeue_io 301: inode 81441 size 0 at 08:07(sda7)
> > > mm/page-writeback.c 668 wb_kupdate: pdflush(147) 17451 global 3936 0 0 wc
> > > _M > tw 1024 sk 2 requeue_io 301: inode 81441 size 0 at 08:07(sda7)
> >
> > Joerg, what's the output of `dumpe2fs /dev/sda7` and `lsof|grep /tmp`?
> 
> After another reboot I tried to get more information about the konqueror 
> process possibly causing the iowait load by using strace -p. Here is the 
> output:
> 
> gettimeofday({1200180588, 878508}, NULL) = 0
> setitimer(ITIMER_VIRTUAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
> rt_sigaction(SIGVTALRM, {SIG_DFL}, {0xb5cffed0, [VTALRM], SA_RESTART}, 8) = 0
> gettimeofday({1200180588, 879942}, NULL) = 0
> time(NULL)                              = 1200180588
> gettimeofday({1200180588, 880838}, NULL) = 0
> gettimeofday({1200180588, 881284}, NULL) = 0

No idea yet :-/ I'm afraid I have to trouble you again - the bug just
refused to appear in my system. I prepared a kernel module for you to
gather more information:

make && insmod ext2-writeback-debug.ko && sleep 1s && rmmod ext2-writeback-debug
dmesg > ext2-writeback-debug.dmesg

Please do it when 100% iowait appears, and send the dmesg file.

Thank you,
Fengguang

View attachment "Makefile" of type "text/plain" (187 bytes)

View attachment "ext2-writeback-debug.c" of type "text/x-csrc" (3608 bytes)