it takes long time to login

[file system]

some times. system runs very slow. it runs idle average 23%

dmesg says 'hw tcp v4 csum failed'
it has lots of messages like above.

can you say that messages?

[Jeroen Peereboom]

Sounds like hardware checksum failed for tcp v4. The NIC (network interface card) may perform checksums on incoming and / or outgoing network traffic.
Network problem? Cabling? NIC defective?

JP

[Sung Oh]

Hello,

I agreed with JP, and you might be able to fix your problem by

1. upgrade your NIC divers

Or

2. Upgrade your kernel to newer version.

you can also check your current network status about checksum errors with following command.

#netstat -s|grep -F -e 'bad segments'

I hope this helps,

Sung