varnishd killed by OOM, How can I configure the varnishd to avoid this problem?

The following error message is taken from my log message. varnishd server is getting killed for over use of memory. We have done all the possible settings to avoid it, Still the same problem happens with multiple VMs, not just one rare incident. Aug 26 08:26:25 host kernel: [15332346.565597] Out of memory in UB 206: OOM killed process 24966 (varnishd) score 0 vm:520484kB, rss:203660kB, swap:12124kB Aug 26 08:26:25 host varnishd: Child (24966) died signal=9 We are having multiple VMs, most of them are running websites. In some VMs, where the load is high, due to limited RAM, the varnishd is getting killed. Some relavent configuration value from /etc/sysconfig/varnish VARNISH_MAX_THREADS=1000 VARNISH_STORAGE_SIZE=256M Server is having 2GB RAM. What configuration needs to be done for varnishd to avoid this problem?