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Posted to user@cassandra.apache.org by Takenori Sato <ts...@cloudian.com> on 2013/09/10 05:50:23 UTC

/proc/sys/vm/zone_reclaim_mode

Hi,

I am investigating NUMA issues.

I have been aware that bin/cassandra tries to use interleave all policy if
available.

https://issues.apache.org/jira/browse/CASSANDRA-2594
https://issues.apache.org/jira/browse/CASSANDRA-3245

So what about /proc/sys/vm/zone_reclaim_mode? Any recommendations? I didn't
find any in respect to Cassandra.

By default on Linux NUMA machine, this is set 1 that tries to reclaim some
pages in a zone rather than acquiring others from the other zones.

Explicitly disabling this sounds better.

"It may be beneficial to switch off zone reclaim if the system is used for
a file server and all of memory should be used for caching files from disk.
In that case the caching effect is more important than data locality."
https://www.kernel.org/doc/Documentation/sysctl/vm.txt

Thanks!
Takenori