From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: NUMA packaging and patch |
Date: | 2014-06-09 16:09:59 |
Message-ID: | 20140609160959.GD8406@alap3.anarazel.de |
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Lists: | pgsql-hackers |
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
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