linux-kernel - Re: Memory policy question for NUMA arch....

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Date:	Wed, 7 Apr 2010 11:00:14 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Rick Sherm <rick.sherm@...oo.com>
Cc:	linux-numa@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Memory policy question for NUMA arch....

On Tue, Apr 06, 2010 at 01:46:44PM -0700, Rick Sherm wrote:
> On a NUMA host, if a driver calls __get_free_pages() then 
> it will eventually invoke ->alloc_pages_current(..). The comment 
> above/within alloc_pages_current() says 'current->mempolicy' will be 
> used.So what memory policy will kick-in if the driver is trying to 
> allocate some memory blocks during driver load time(say from probe_one)? System-wide default policy,correct?

Actually the policy of the modprobe or the kernel boot up if built in
(which is interleaving)

> 
> What if the driver wishes to i) stay confined to a 'cpulist' OR ii) use a different mem-policy? How 
> do I achieve this?
> I will choose the 'cpulist' after I am successfuly able to affinitize the MSI-X vectors.

You can do that right now by running numactl ... modprobe ...

Yes there should be probably a better way, like using a policy
based on the affinity of the PCI device.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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