linux-kernel - Re: [PATCH 6/8] Add __GFP_OTHER

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Date:	Tue, 22 Feb 2011 13:47:47 -0800
From:	Andi Kleen <ak@...ux.intel.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrea Arcangeli <aarcange@...hat.com>, lwoodman@...hat.com
Subject: Re: [PATCH 6/8] Add __GFP_OTHER_NODE flag

On 2/22/2011 1:42 PM, David Rientjes wrote:
>
> This makes the accounting worse, NUMA_LOCAL is defined as "allocation from
> local node," meaning it's local to the allocating cpu, not local to the
> node being targeted.

Local to the process really (and I defined it originally ...)  That is 
what I'm implementing

I don't think "local to some random kernel daemon which changes mappings 
on behalf of others"
makes any sense as semantics.

> Further, preferred_zone has taken on a much more significant meaning other
> than just statistics: it impacts the behavior of memory compaction and how
> long congestion timeouts are, if a timeout is taken at all, depending on
> the I/O being done on behalf of the zone.
>
> A better way to address the issue is by making sure preferred_zone is
> actually correct by using the appropriate zonelist to be passed into the
> allocator in the first place

That is what is done already (well for THP together with my other patches)
The problem is just that local_hit/miss still uses numa_node_id() and 
not the preferred zone
to do the accounting.  In most cases that's fine and intended, just not 
for these
special daemons.


-Andi

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