* deadlock with btrfs heavy i/o and kswapd
@ 2016-09-22 6:41 Stefan Priebe - Profihost AG
2016-09-22 14:28 ` Chris Mason
0 siblings, 1 reply; 4+ messages in thread
From: Stefan Priebe - Profihost AG @ 2016-09-22 6:41 UTC (permalink / raw)
To: linux-btrfs
Hi,
i always encounter btrfs deadlocks / hung tasks, when i have a lot of
cached mem and i'm doing heavy rsync --inplace operations in my system
from btrfs zlib compressed disk A to btrfs zlib compressed disk B.
The last output i see in this case is kswapd0 running for a long time at
100% cpu. Then the whole system get's stuck. I cannot connect to ssh
anymore but the kernel still prints hung tasks every few minutes.
May be relevant the system has NO swap.
vm.vfs_cache_pressure = 100
vm.swappiness = 50
Greets,
Stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: deadlock with btrfs heavy i/o and kswapd
2016-09-22 6:41 deadlock with btrfs heavy i/o and kswapd Stefan Priebe - Profihost AG
@ 2016-09-22 14:28 ` Chris Mason
2016-09-26 6:59 ` Stefan Priebe - Profihost AG
2016-09-27 6:41 ` Stefan Priebe - Profihost AG
0 siblings, 2 replies; 4+ messages in thread
From: Chris Mason @ 2016-09-22 14:28 UTC (permalink / raw)
To: Stefan Priebe - Profihost AG, linux-btrfs
On 09/22/2016 02:41 AM, Stefan Priebe - Profihost AG wrote:
> Hi,
>
> i always encounter btrfs deadlocks / hung tasks, when i have a lot of
> cached mem and i'm doing heavy rsync --inplace operations in my system
> from btrfs zlib compressed disk A to btrfs zlib compressed disk B.
>
> The last output i see in this case is kswapd0 running for a long time at
> 100% cpu. Then the whole system get's stuck. I cannot connect to ssh
> anymore but the kernel still prints hung tasks every few minutes.
>
> May be relevant the system has NO swap.
>
> vm.vfs_cache_pressure = 100
> vm.swappiness = 50
Are you able to capture the stack dumps? A sysrq-w would really help.
-chris
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: deadlock with btrfs heavy i/o and kswapd
2016-09-22 14:28 ` Chris Mason
@ 2016-09-26 6:59 ` Stefan Priebe - Profihost AG
2016-09-27 6:41 ` Stefan Priebe - Profihost AG
1 sibling, 0 replies; 4+ messages in thread
From: Stefan Priebe - Profihost AG @ 2016-09-26 6:59 UTC (permalink / raw)
To: Chris Mason, linux-btrfs
Am 22.09.2016 um 16:28 schrieb Chris Mason:
>
>
> On 09/22/2016 02:41 AM, Stefan Priebe - Profihost AG wrote:
>> Hi,
>>
>> i always encounter btrfs deadlocks / hung tasks, when i have a lot of
>> cached mem and i'm doing heavy rsync --inplace operations in my system
>> from btrfs zlib compressed disk A to btrfs zlib compressed disk B.
>>
>> The last output i see in this case is kswapd0 running for a long time at
>> 100% cpu. Then the whole system get's stuck. I cannot connect to ssh
>> anymore but the kernel still prints hung tasks every few minutes.
>>
>> May be relevant the system has NO swap.
>>
>> vm.vfs_cache_pressure = 100
>> vm.swappiness = 50
>
> Are you able to capture the stack dumps? A sysrq-w would really help.
I wasn't as my netconsole didn't work even on the screen no traces were
visible. Currently i can't reproduce this. I'm still fighting with my
ENOSPC problems while using btrfs and reflinks which is a currently a
showstopper for me.
Greets,
Stefan
> -chris
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: deadlock with btrfs heavy i/o and kswapd
2016-09-22 14:28 ` Chris Mason
2016-09-26 6:59 ` Stefan Priebe - Profihost AG
@ 2016-09-27 6:41 ` Stefan Priebe - Profihost AG
1 sibling, 0 replies; 4+ messages in thread
From: Stefan Priebe - Profihost AG @ 2016-09-27 6:41 UTC (permalink / raw)
To: Chris Mason, linux-btrfs
Hi Chris,
today i had this again. But i can't see any stack traces. I just see.
INFO: kworker/u128:5:24301 blocked for more than 120 seconds.
...
INFO: kworker/u128:5:24301 blocked for more than 120 seconds.
...
INFO: task mysqld:929 blocked for more ...
...
sysrq w just prints:
sysrq: SysRq: Show Blcoked State
but nothing more.
Stefan
Am 22.09.2016 um 16:28 schrieb Chris Mason:
>
>
> On 09/22/2016 02:41 AM, Stefan Priebe - Profihost AG wrote:
>> Hi,
>>
>> i always encounter btrfs deadlocks / hung tasks, when i have a lot of
>> cached mem and i'm doing heavy rsync --inplace operations in my system
>> from btrfs zlib compressed disk A to btrfs zlib compressed disk B.
>>
>> The last output i see in this case is kswapd0 running for a long time at
>> 100% cpu. Then the whole system get's stuck. I cannot connect to ssh
>> anymore but the kernel still prints hung tasks every few minutes.
>>
>> May be relevant the system has NO swap.
>>
>> vm.vfs_cache_pressure = 100
>> vm.swappiness = 50
>
> Are you able to capture the stack dumps? A sysrq-w would really help.
>
> -chris
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-09-27 6:41 UTC | newest]
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2016-09-22 6:41 deadlock with btrfs heavy i/o and kswapd Stefan Priebe - Profihost AG
2016-09-22 14:28 ` Chris Mason
2016-09-26 6:59 ` Stefan Priebe - Profihost AG
2016-09-27 6:41 ` Stefan Priebe - Profihost AG
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