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SubjectRe: 100% iowait on one of cpus in current -git
Date
On Monday 22 October 2007 11:41:57 Peter Zijlstra wrote:
> On Mon, 2007-10-22 at 08:22 +0200, Maxim Levitsky wrote:
> > Hi,
> >
> > I found a bug in current -git:
> >
> > On my system on of cpus stays 100% in iowait mode (I have core 2 duo)
> > Otherwise the system works OK, no disk activity and/or slowdown.
> > Suspecting that this is a swap-related problem I tried to turn swap of, but it doesn't affect anything.
> > It is probably some accounting bug.
> >
> > If I start with init=/bin/bash, then this disappears.
> > I tried then to start usual /etc/init.d scripts then, and first one to show this bug was gpm.
> > but then I rebooted the system to X without gpm, and I still see 100% iowait.
> >
> > No additional messages in dmesg.
>
> does sysrq-t show any D state tasks?
>
>
This one:
Probably per-block device dirty writeback?
I am compiling now revision 1f7d6668c29b1dfa307a44844f9bb38356fc989b
Thanks for the pointer.



[ 673.365631] pdflush D c21bdecc 0 221 2
[ 673.365635] c21bdee0 00000046 00000002 c21bdecc c21bdec4 00000000 c21b3000 00000002
[ 673.365643] c0134892 c21b3164 c1e00200 00000001 c7109280 c21bdec0 c03ff849 c21bdef0
[ 673.365650] 00052974 00000000 000000ff 00000000 00000000 00000000 c21bdef0 000529dc
[ 673.365657] Call Trace:
[ 673.365659] [<c03fd728>] schedule_timeout+0x48/0xc0
[ 673.365663] [<c03fd50e>] io_schedule_timeout+0x5e/0xb0
[ 673.365667] [<c0170d11>] congestion_wait+0x71/0x90
[ 673.365671] [<c016b92e>] wb_kupdate+0x9e/0xf0
[ 673.365675] [<c016beb2>] pdflush+0x102/0x1d0
[ 673.365679] [<c013fa82>] kthread+0x42/0x70
[ 673.365683] [<c01050df>] kernel_thread_helper+0x7/0x18


Best regards,
Maxim Levitsky
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