Re: [vserver] High Systemload and many Processes in D state

From: Urban Loesch <bind_at_enas.net>
Date: Fri 18 May 2012 - 16:55:25 BST
Message-ID: <4FB670ED.50502@enas.net>

On 18.05.2012 15:56, Ghislain wrote:
> Le 18/05/2012 15:30, Urban Loesch a écrit :
>> Hi Gishlain,
>>
>> thanks for your anwser.
>>
>> If I stop Dovecot then I have to wait a couple of minutes (2-3) and all the processes in D state are disappearing.
>> Also the kernel thread [fsnotify_mark] goes in sleep state and the systemload goes down to normal values.
>>
>
> lucky one mine was D state process locked and only reboot can cure it.

I tested it again to be sure. After stpping Dovecot and wating 2 minutes all D states are gone.

>
>> I use the following cgroup limits:
>>
>> mount options:
>> vserver on /dev/cgroup type cgroup (rw,cpuset,cpu,cpuacct,memory,devices,freezer,net_cls,blkio,perf_event)
>>
>>
>> In /etc/vservers/$VSNAME/cgroup" if have:
>>
>> cpuset.cpus: 0-5
>> cpu.shares: 512
>> memory.limit_in_bytes: 4G
>> memory.memsw.limit_in_bytes: 6G
>
> perhaps you should remove blkio from the cgroup if you do not use it as it seems to be from my point of view the culprit as this is what appeared on
> those versions. As all my servers are vserver patched i really do not know if this is related to cgroup/vserver i never been ale to have a valuable
> trace on this issue. 3.0.28 is pretty recent one so this is curious.

First I tried with "blkio" disabled
mount:
vserver on /dev/cgroup type cgroup (rw,cpuset,cpu,cpuacct,memory,devices,freezer,net_cls,perf_event)

After a couple of minutes the "[fsnotify_mark]" was in D state again.

Now I unmounted cgroup completly. I don't need it on this machine.
Now for 20 minutes it runs normaly.

The [fsnotify_mark] sometimes comes up in D state, but goes in sleep state some seconds after:

# vps -ostat,pid,time,wchan='WCHAN-xxxxxxxxxxxxxxxxxxxx',cmd ax |grep D
STAT PID CONTEXT TIME WCHAN-xxxxxxxxxxxxxxxxxxxx CMD
D 93 0 MAIN 00:00:12 synchronize_sched [fsnotify_mark]
S+ 30193 0 MAIN 00:00:00 pipe_wait grep D
# vps -ostat,pid,time,wchan='WCHAN-xxxxxxxxxxxxxxxxxxxx',cmd ax |grep D
STAT PID CONTEXT TIME WCHAN-xxxxxxxxxxxxxxxxxxxx CMD
S+ 30599 0 MAIN 00:00:00 pipe_wait grep D

The only thing no is, that vserver-stat gimves me no more status info:

# vserver-stat
open(memory.stat): No such file or directory
CTX PROC VSZ RSS userTIME sysTIME UPTIME NAME
154 598 15.5G 0 0m00s00 0m00s00 19m54s54 vsmail1

Perhaps I should try with 3.2.17?

>
>>
>> Currently there is only 1 vServer running on this Host.
>>
>
> this is how i use it most of the time ^^ hardware issue free migration and i keep ssh access even if the guest is hacked...
>
>> Perhaps I should completly disable cgroup? Do you know how I can do this?
>
> disbale no but remount it with blkio disabled to see if it helps.
>
>>
>> Sorry, but I have never heard about dlimit?
>
> then i guess you do not use them ^^

I googled :-)
dlimit is for IO throttling, etc. No I don't need it.

>
> Ghislain.
>

Thanks
Urban
Received on Fri May 18 16:55:30 2012

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