Re: [RFC] Reverting NUMA-affine page table allocation

From: Yinghai Lu
Date: Wed Mar 02 2011 - 11:48:00 EST


On 03/02/2011 08:19 AM, Tejun Heo wrote:
> > Hey, Yinghai.
> >
> > On Tue, Mar 01, 2011 at 02:41:55PM -0800, Yinghai Lu wrote:
>>> >>> 2. find_early_table_space() always calculates the amount of the needed
>>> >>> space from 0 to the specified @end. As nodes are registered, each
>>> >>> node would try to allocate accumulative amount of space for page
>>> >>> table. This probably wouldn't cause any actual problem (may affect
>>> >>> emulated configurations a bit tho).
>> >>
>> >> interesting.
> >
> > Yeah, it's a pretty interesting piece of code in need of some cleanup.
No, i mean second one is not causing any problem.

that only take end is intentionally. that will make sure we can get
space for page table even in extreme case.

> >
> > I'm reverting the NUMA-affine page table allocation for now. I wish
> > something like the following happens during the next devel cycle.
> >
> > * General cleanup of page table allocation code. I'm not talking
> > about major rewrite or anything major. Just making the code sane(r)
> > so that they take parameters instead of doing subtle stuff with
> > internal #ifdef's. And hopefully proper documentation.
> >
> > * Redo the NUMA-affine page table allocation in simpler way using
> > cleaned up allocation functions. As suggested before, IMO, just
> > taking top and bottom of nodes is enough. Again, hopefully, with
> > enough documentation on both what and why.
> >
> > If you're interested in doing the above, please go ahead and let me
> > know.

No. please don't revert it.

Ingo, please get patches that will align to 1G ... from

git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-2.6-yinghai.git
memblock

Thanks

Yinghai
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