Hi, I am testing cassandra 1.1 on a 1 node cluster. 8 core, 16 gb ram, 6 data disks raid0, no swap configured
cassandra 1.1.1 heap size: 8 gigs key cache size in mb: 800 (used only 200mb till now) memtable_total_space_in_mb : 2048 I am running a read workload.. about 30 reads/second. no writes at all. The system runs fine for roughly 12 hours. jconsole shows that my heap size has hardly touched 4 gigs. top shows - SHR increasing slowly from 100 mb to 6.6 gigs in these 12 hrs RES increases slowly from 6 gigs all the way to 15 gigs buffers are at a healthy 25 mb at some point and that goes down to 2 mb in these 12 hrs VIRT stays at 85 gigs I understand that SHR goes up because of mmap, RES goes up because it is showing SHR value as well. After around 10-12 hrs, the cpu utilization of the system starts increasing, and i notice that kswapd0 process starts becoming more active. Gradually, the system cpu becomes high almost 70%, and the client starts getting continuous timeouts. The fact that the buffers went down from 20 mb to 2 mb suggests that kswapd0 is probably swapping out the pagecache. Is there a way out of this to avoid the kswapd0 starting to do things even when there is no swap configured? This is very easily reproducible for me, and would like a way out of this situation. Do i need to adjust vm memory management stuff like pagecache, vfs_cache_pressure.. things like that? just some extra information, jna is installed, mlockall is successful. there is no compaction running. would appreciate any help on this. Thanks Gurpreet
