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From: David Rientjes <rientjes@google.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Anton Blanchard <anton@samba.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: ppc: RECLAIM_DISTANCE 10?
Date: Wed, 19 Feb 2014 13:45:14 -0800 (PST)	[thread overview]
Message-ID: <alpine.DEB.2.02.1402191339000.31921@chino.kir.corp.google.com> (raw)
In-Reply-To: <20140219091959.GD14783@dhcp22.suse.cz>

On Wed, 19 Feb 2014, Michal Hocko wrote:

> Interesting. So is the PPC NUMA basically about local vs. very distant?

The point is that it's impossible to tell how distant they are from one 
NUMA domain to the next NUMA domain.

> Should REMOTE_DISTANCE reflect that as well? Or can we have 
> distance < REMOTE_DISTANCE and it would still make sense to have
> zone_reclaim enabled?
> 

Ppc doesn't want to allocate in a different NUMA domain unless required, 
the latency of a remote access is too high.  Everything that isn't in the 
same domain has a distance >10 and is setup as 2^(domain hops) * 10.  We 
don't have the ability like with a SLIT to define remote nodes to have 
local latency vs remote or costly latency so the safe setting is a 
RECLAIM_DISTANCE of 10.

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  reply	other threads:[~2014-02-19 21:45 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-18  9:06 Michal Hocko
2014-02-18 22:27 ` David Rientjes
2014-02-19  8:16   ` Michal Hocko
2014-02-19  8:20     ` David Rientjes
2014-02-19  9:19       ` Michal Hocko
2014-02-19 21:45         ` David Rientjes [this message]
2014-02-18 23:34 ` Nishanth Aravamudan
2014-02-18 23:58   ` Nishanth Aravamudan
2014-02-19  0:40     ` Nishanth Aravamudan
2014-02-19  1:43     ` David Rientjes
2014-02-19  8:33       ` Michal Hocko
2014-02-19 16:24       ` Nishanth Aravamudan
2014-02-19 16:33         ` Nishanth Aravamudan
2014-02-20  9:55           ` Michal Hocko
2014-02-19  8:23   ` Michal Hocko
2014-02-19 16:26     ` Nishanth Aravamudan
2014-02-19 17:03     ` [RFC PATCH] mm: exclude memory less nodes from zone_reclaim Michal Hocko
2014-02-19 17:16       ` Nishanth Aravamudan
2014-02-19 17:32         ` Michal Hocko
2014-02-19 17:49           ` Nishanth Aravamudan
2014-02-19 19:40             ` Michal Hocko
2014-02-19 17:53       ` Nishanth Aravamudan
2014-02-19 21:56         ` David Rientjes
2014-02-19 23:05           ` Nishanth Aravamudan
2014-02-20  9:50             ` Michal Hocko

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