* kernel thread "flush-254:12" eats 100% CPU
@ 2011-09-07 15:46 Marcin M
2011-09-07 17:27 ` Marcin M
2011-09-08 5:15 ` Tao Ma
0 siblings, 2 replies; 5+ messages in thread
From: Marcin M @ 2011-09-07 15:46 UTC (permalink / raw)
To: linux-ext4
Hello!
I hope i'm writing to correct place (but i suspect g.l.kernel list could
be proper also) :)
I'm observing situation like in subject. From time to time
"flush-254:12" takes 100% of cpu for a couple of minutes. Then
everything becomes ok.
This problem appears on my two different boxes.
box A)
bare metal, i686, hardened-kernel-2.6.{37-38}
on this box kernel thread never stops to do 100% of cpu. I've to reboot
box (using sysrq, because i could't even umount partition associated
with this thread)
My workarround for it: i changed ext4 to xfs on dm device and problem
disappeared
box B)
xen, full virtualization, x86_64, kernels:
hardened-kernel-{2.6.39,3.0.3,3.0.4} and 3.1.0-rc4-git2
problem is as i described above, flush took one cpu for a couple minutes
and then everythings works correctly.
And again, 254-12 device is ext4 filesystem.
In both cases it was used lvm. At box B, additionaly i'm using dmcrypt.
Box B is configured in this way: sda->lvm2->dmcrypt->filesystem.
How can i help to debug this problem? Or maybe it's fixed already?
Regards,
Marcin.
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: kernel thread "flush-254:12" eats 100% CPU
2011-09-07 15:46 kernel thread "flush-254:12" eats 100% CPU Marcin M
@ 2011-09-07 17:27 ` Marcin M
2011-09-08 5:15 ` Tao Ma
1 sibling, 0 replies; 5+ messages in thread
From: Marcin M @ 2011-09-07 17:27 UTC (permalink / raw)
To: linux-ext4
Suplement.
High cpu load appears in random time interval.
All filesystems which has this problem was created with smaller than
default block size. I've got a few other fs with small black size but
thread flush-254 always appear on the same device.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: kernel thread "flush-254:12" eats 100% CPU
2011-09-07 15:46 kernel thread "flush-254:12" eats 100% CPU Marcin M
2011-09-07 17:27 ` Marcin M
@ 2011-09-08 5:15 ` Tao Ma
2011-09-08 9:45 ` Marcin M
2011-09-26 13:50 ` Marcin M
1 sibling, 2 replies; 5+ messages in thread
From: Tao Ma @ 2011-09-08 5:15 UTC (permalink / raw)
To: Marcin M; +Cc: linux-ext4
On 09/07/2011 11:46 PM, Marcin M wrote:
> Hello!
> I hope i'm writing to correct place (but i suspect g.l.kernel list could
> be proper also) :)
> I'm observing situation like in subject. From time to time
> "flush-254:12" takes 100% of cpu for a couple of minutes. Then
> everything becomes ok.
> This problem appears on my two different boxes.
>
> box A)
> bare metal, i686, hardened-kernel-2.6.{37-38}
> on this box kernel thread never stops to do 100% of cpu. I've to reboot
> box (using sysrq, because i could't even umount partition associated
> with this thread)
> My workarround for it: i changed ext4 to xfs on dm device and problem
> disappeared
So do you have the backstrace for it? Just wonder what it is doing.
echo t > /proc/sysrq-trigger should tell us what the flusher is doing at
that time.
Thanks
Tao
>
> box B)
> xen, full virtualization, x86_64, kernels:
> hardened-kernel-{2.6.39,3.0.3,3.0.4} and 3.1.0-rc4-git2
> problem is as i described above, flush took one cpu for a couple minutes
> and then everythings works correctly.
>
> And again, 254-12 device is ext4 filesystem.
> In both cases it was used lvm. At box B, additionaly i'm using dmcrypt.
> Box B is configured in this way: sda->lvm2->dmcrypt->filesystem.
>
> How can i help to debug this problem? Or maybe it's fixed already?
>
> Regards,
> Marcin.
>
> --
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: kernel thread "flush-254:12" eats 100% CPU
2011-09-08 5:15 ` Tao Ma
@ 2011-09-08 9:45 ` Marcin M
2011-09-26 13:50 ` Marcin M
1 sibling, 0 replies; 5+ messages in thread
From: Marcin M @ 2011-09-08 9:45 UTC (permalink / raw)
To: linux-ext4
W dniu 08.09.2011 07:15, Tao Ma pisze:
> So do you have the backstrace for it? Just wonder what it is doing.
> echo t> /proc/sysrq-trigger should tell us what the flusher is doing at
> that time.
I don't have backstrace, if you tellme how to get it then i'll do it:)
I did echo t>.... when flush was too active, here it is:
[70946.742426] flush-254:12 R running task 0 27198 2
0x00000000
[70946.742426] ffff88001ea5bde0 0000000000000046 0000000000000265
ffff88001ead56a0
[70946.742426] 000000000000fe00 ffff88000f515fd8 0000000000004000
ffff88000f514000
[70946.742426] ffff88000f515fd8 000000000000fe00 ffff88001ea5bde0
000000000000fe00
[70946.742426] Call Trace:
[70946.742426] [<ffffffff8119d2c3>] ?
radix_tree_gang_lookup_tag_slot+0x83/0xe0
[70946.742426] [<ffffffff81083a43>] ? find_get_pages_tag+0x33/0x130
[70946.742426] [<ffffffff8102ed7d>] ? __cond_resched+0x1d/0x30
[70946.742426] [<ffffffff812fb50f>] ? _cond_resched+0x2f/0x40
[70946.742426] [<ffffffff811353ef>] ? write_cache_pages_da+0x32f/0x380
[70946.742426] [<ffffffff8115d7f5>] ? jbd2__journal_start+0xd5/0x120
[70946.742426] [<ffffffff8113f358>] ? ext4_journal_start_sb+0x68/0x170
[70946.742426] [<ffffffff8113567e>] ? ext4_da_writepages+0x23e/0x440
[70946.742426] [<ffffffff810ee72e>] ? writeback_single_inode+0x11e/0x2c0
[70946.742426] [<ffffffff810eecb0>] ? writeback_sb_inodes+0x1c0/0x280
[70946.742426] [<ffffffff810ef17e>] ? __writeback_inodes_wb+0x8e/0xc0
[70946.742426] [<ffffffff810ef383>] ? wb_writeback+0x1d3/0x1e0
[70946.742426] [<ffffffff810e4791>] ? get_nr_dirty_inodes+0x51/0x80
[70946.742426] [<ffffffff810efbfe>] ? wb_do_writeback+0x1ce/0x1e0
[70946.742426] [<ffffffff810efc92>] ? bdi_writeback_thread+0x82/0x150
[70946.742426] [<ffffffff810efc10>] ? wb_do_writeback+0x1e0/0x1e0
[70946.742426] [<ffffffff810efc10>] ? wb_do_writeback+0x1e0/0x1e0
[70946.742426] [<ffffffff81050a46>] ? kthread+0x96/0xa0
[70946.742426] [<ffffffff812fe974>] ? kernel_thread_helper+0x4/0x10
[70946.742426] [<ffffffff810509b0>] ? kthread_worker_fn+0x120/0x120
[70946.742426] [<ffffffff812fe970>] ? gs_change+0xb/0xb
Thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: kernel thread "flush-254:12" eats 100% CPU
2011-09-08 5:15 ` Tao Ma
2011-09-08 9:45 ` Marcin M
@ 2011-09-26 13:50 ` Marcin M
1 sibling, 0 replies; 5+ messages in thread
From: Marcin M @ 2011-09-26 13:50 UTC (permalink / raw)
To: linux-ext4
Hello,
Is it something that i can do to help with this problem?
Regards.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-09-26 13:50 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2011-09-07 15:46 kernel thread "flush-254:12" eats 100% CPU Marcin M
2011-09-07 17:27 ` Marcin M
2011-09-08 5:15 ` Tao Ma
2011-09-08 9:45 ` Marcin M
2011-09-26 13:50 ` Marcin M
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