[Beowulf] big read triggers migration and slow memory IO?

[Stuart Barkley]

On Wed, 8 Jul 2015 at 17:26 -0000, mathog wrote:

> This big Dell (PowerEdge T620/03GCP, 48 CPUs, >500Gb RAM) keeps
> throwing me curve balls.

Even though I doubt it is your problem, this smells similar to the
zone_reclaim_mode issues we saw last year.

You might check 'sar -B' output.  Specifically the 'pgscand/s' column.

Check the setting of /proc/sys/vm/zone_reclaim_mode (it should be 0).

See: http://www.beowulf.org/pipermail/beowulf/2014-September/032835.html

Stuart
-- 
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