On 2014-06-09 08:59:03 -0700, Kevin Grittner wrote:
> > *) There is a lot of advice floating around (for example here:
> > http://frosty-postgres.blogspot.com/2012/08/postgresql-numa-and-zone-reclaim-mode.html )
> > to instruct operators to disable zone_reclaim. Will your changes
> > invalidate any of that advice?
>
> I expect that it will make the need for that far less acute,
> although it is probably still best to disable zone_reclaim (based
> on the documented conditions under which disabling it makes sense).
I think it'll still be important unless you're running an OLTP workload
(i.e. minimal per backend allocations) and your entire workload fits
into shared buffers. What zone_reclaim > 0 essentially does is to never
allocate memory from remote nodes. I.e. it will throw away all numa node
local OS cache to satisfy a memory allocation (including
pagefaults).
I honestly wouldn't expect this to make a huge difference *wrt*
zone_reclaim_mode.
Greetings,
Andres Freund
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services
