On Fri, Jun 05, 2015 at 09:21:43PM +0200, Markus "Shorty" Uckelmann wrote:
If you don't explicitly lock things into memory, file I/O can and will cause idle pages to get pushed out. It happens less often if you manipulate swappines.
So, is a swappiness value of 60 not recommended for servers?
It's probably a fine default. For my most recent purposes, a web-scale search engine, I locked a ton of daemons into memory with mlockall (on latency-optimized clusters) and set swappiness to 0 on all clusters (including batch-optimized clusters.)
This last bit was because I don't expect my systems to ever swap... I only have a small amount of swap configured to reduce the mayhem caused by OOMs, and give my home-grown oom daemon (which is locked into memory, of course) time to open fire on my choice of offending process.
-- greg