[CentOS] kswapd taking 100% cpu with no swap on system

Mon May 9 13:07:57 UTC 2011
Ali Ahsan <ali.ahsan at panasiangroup.com>

Thanks for reply,I dont know it has some thing to do with linux 
scheduler  but some on suggested about linux scheduler cat 
/sys/block/sda/queue/scheduler there are quite few of them noop 
[anticipatory] deadline cfq.I have changed from cfq default to 
anticipatory,Now problem is less for me kswapd0  take 10-50% of cpu in 
very short bust less then milliseconds.Also i have changed 
/proc/sys/vm/pagecache from 100 to 10.  Any more suggestion will help me 
make server better,As for i have read the best scheduler for databases 
are deadline like for mysql it worked great.

On 05/09/2011 06:01 PM, Peter Kjellström wrote:
> On Saturday, May 07, 2011 09:35:48 PM Ali Ahsan wrote:
>> Hi All
>> I have xeon server with 16 Gb Ram and no Swap memory.I am running
>> cassandra server on two node in cluster.When there is high load on
>> server kswapd0 kicks inn and take 100% cpu and make machine very slow
>> and we need to restart out cassandra server.I have  latest kernel
>> 2.6.18-238.9.1.el5.Please let me know how can i fix this issue .Its
>> hurting us badly this our production server any quick help will be
>> appreciated.
> There is more than one bug that causes this behaviour. A few related memory
> managent situations (possibly responsible) may actually be avoided if you add
> some swap (even if it's not used). My suggestion would be to add some swap,
> set swappiness to 0 and see what happens.
> /Peter
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S.Ali Ahsan

Senior System Engineer

e-Business (Pvt) Ltd

49-C Jail Road, Lahore, P.O. Box 676
Lahore 54000, Pakistan

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Email: ali.ahsan at panasiangroup.com



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