How to handle high cpu usage due to Kswapd process

Hi,

We have a server running SAP applications. Recently kswapd used 99% sys and load was around 130 and machine hanged completely.

RHEL 5.8 64 Bit
RAM is 28 GB, SWAP is 20 GB

Out of this 17 GB RAM was used and 9 GB cache was still present. SWAP usage was 3 GB. But there was no pages in/out and swap in/out at that time.

Only thing was there were many SAP application processes in running state continuously. And to fix the issue, server was rebooted.

Please share details on swap fine tuning

Thanks
Iyappan V