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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