Re: [PATCH]: Clean up of __alloc_pages

[Rohit Seth <rohit.seth@intel.com>]

On Mon, 2005-10-03 at 09:57 -0700, Christoph Lameter wrote:
> On Mon, 3 Oct 2005, Rohit Seth wrote:
> 
> > > Seems that this removes the logic intended to prefer local 
> > > allocations over remote pages present in the existing alloc_pages? There 
> > > is the danger that this modification will lead to the allocation of remote 
> > > pages even if local pages are available. Thus reducing performance.
> > Good catch.  I will up level the cpuset check in buffered_rmqueue rather
> > then doing it in get_page_from_freelist.  That should retain the current
> > preferences for local pages.
> 
> This is not only the cpuset check. If there is memory available in an 
> earlier zone then it needs to be taken regardless of later pcp's 
> the zonelist containing pages. Otherwise we did not take the pages nearest 
> to the requested node.
> 

Ah.  Okay.

> > > I would suggest to just check the first zone's pcp instead of all zones.
> > > 
> > 
> > Na. This for most cases will be ZONE_DMA pcp list having nothing much
> > most of the time.  And picking any other zone randomly will be exposed
> > to faulty behavior.
> 
> Maybe only check the first node?
> 

I think conceptually this ask for a new flag __GFP_NODEONLY that
indicate allocations to come from current node only. 

This definitely though means I will need to separate out the allocation
from pcp patch (as Nick suggested earlier).

-rohit

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