Re: [PATCH] mempolicy:add GFP_THISNODE when allocing new page

[Bob Liu <lliubbo@gmail.com>]

On Tue, Apr 20, 2010 at 1:47 AM, Christoph Lameter
<cl@linux-foundation.org> wrote:
> On Sat, 17 Apr 2010, Bob Liu wrote:
>
>> > GFP_THISNODE forces allocation from the node. Without it we will fallback.
>> >
>>
>> Yeah, but I think we shouldn't fallback at this case, what we want is
>> alloc a page
>> from exactly the dest node during migrate_to_node(dest).So I added
>> GFP_THISNODE.
>
> Why would we want that?
>

Because if dest node have no memory, it will fallback to other nodes.
The dest node's fallback nodes may be nodes in nodemask from_nodes.
It maybe make circulation ?.(I am not sure.)

What's more,i think it against the user's request.
The user wants to move pages from from_nodes to to_nodes, if fallback
happened, the pages may be moved to other nodes instead of any node in
nodemask to_nodes.
I am not sure if the user can expect this and accept.

Thanks a lot for your patient reply. :)
-- 
Regards,
--Bob

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