Re: [PATCH v6][RFC] Fix hugetlb pool allocation with empty nodes

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 11.06.2007 [20:19:24 -0700], Christoph Lameter wrote:
> On Mon, 11 Jun 2007, Nishanth Aravamudan wrote:
> 
> > > Ahh did not see that. Can you not call simply into interleave() from 
> > > mempolicy.c? It will get you the counter that you need.
> > 
> > You just told me that mempolicy.c is built conditionally on NUMA.
> > alloc_fresh_huge_page() is not, it only depeonds on CONFIG_HUGETLB_PAGE!
> 
> Well you just need to have the appropriate fallbacks defined in
> mempolicy.h

Ok, I understand that.

> > The only interleave functions I see in mempolicy.c are:
> > 
> > interleave_nodes(), which takes a mempolicy, which I don't have in
> > hugetlb.c
> > 
> > interleave_nid(), which also takes a mempolicy
> > 
> > I guess I could try and use huge_zonelist(), but I don't see the point?
> 
> Export a function for the interleave functionality so that we do not
> have to replicate the same thing in various locations in the kernel.

But I don't understand this at all.

This is *not* generically available, unless every caller has its own
private static variable. I don't know how to do that in C.

You're asking me to complicate patches that work just fine right now.
Well, excluding a hasty patch that I didn't compile-test. All I'm trying
to do is ask for some guidance.

What we have here is:

alloc_fresh_huge_page() should return 1 after a successful allocation of
a huge page on a different node, in a round-robin fashion, on every
invocation; or 0, if no huge page could be allocated.

I don't see how to make that generic in a simple way. It relies on an
interator that is private to the function, not to any structure. And
this is really a one-time allocation right now (hugepages).

Thanks,
Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

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