Re: [PATCH] populated_map: fix !NUMA case, remove comment

[Lee Schermerhorn <Lee.Schermerhorn@hp.com>]

On Tue, 2007-06-12 at 10:28 -0700, Nishanth Aravamudan wrote:
> On 12.06.2007 [11:06:22 -0400], Lee Schermerhorn wrote:
<snip>
> > 
> > Nish:  when this all settles down, I still need to make sure it works
> > on our platforms with the funny DMA-only node.  What that comes down
> > to is that when alloc_fresh_huge_page() calls:
> 
> Ok, thanks for these details.
> 
> Would you be ok with stabilizing the generic definition of
> node_populated_map as is (any present pages, regardless of location),
> and then trying to figure out how to get your platform to work with
> that?

Yeah, I think that's my only option now that node_populated_map is being
used for other things than huge page setup.

> 
> > 		page = alloc_pages_node(nid,
> >                                GFP_HIGHUSER|__GFP_COMP|GFP_THISNODE,
> >                                HUGETLB_PAGE_ORDER);
> > 
> > I need to get a page that is on nid.  On our platform, GFP_HIGHUSER is
> > going to specify the zonelist for ZONE_NORMAL.  The first zone on this
> > list needs to be on-node for nid.  With the changes you've made to the
> > definition of populated map, I think this won't be the case.  I need
> > to test your latest patches and fix that, if it's broken.
> 
> Ok. But that means your platform is broken now too, right? As in, it's
> not a regression, per se?

Well, my patch [v4] fixed it on my platform.  So this is a regression
relative to my patch.  But, then, my patch had an issue with an x86_64
system where one node is all/mostly DMA32 and other nodes have memory in
higher zones.  Maybe that's OK [or not] for hugepage allocation, but
almost certainly not for regular page interleaving, ...

> 
> I'm much more concerned in the short term about the whole
> memoryless-node issue, which I think is more straight-forward, and
> generic to fix.

Perhaps, but I think we're still going to get off node allocations with
the revised definition of the populated map and the new zonelist
ordering.  I think we'll need to check for and reject off-node
allocations when '_THISNODE is specified.  We can't assume that the
first zone in a node's zonelist for a given gfp_zone is on-node.

[more in response to other mail...]

Lee

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