Re: [RFC] memory defragmentation to satisfy high order allocations

From: Marcelo Tosatti
Date: Fri Oct 01 2004 - 15:41:35 EST


On Fri, Oct 01, 2004 at 01:11:47PM -0700, Andrew Morton wrote:
> Marcelo Tosatti <marcelo.tosatti@xxxxxxxxxxxx> wrote:
> >
> > The following patch implements a "coalesce_memory()" function
> > which takes "zone" and "order" as a parameter.
> >
> > It tries to move enough physically nearby pages to form a free area
> > of "order" size.
> >
> > It does that by checking whether the page can be moved, allocating a new page,
> > unmapping the pte's to it, copying data to new page, remapping the ptes,
> > and reinserting the page on the radix/LRU.
>
> Presumably this duplicates some of the memory hot-remove patches.

As far as I have researched, the memory moving/remapping code
on the hot remove patches dont work correctly. Please correct me.

And what I've seen (from the Fujitsu guys) was quite ugly IMHO.

> Apparently Dave Hansen has working and sane-looking hot remove code
> which is in a close-to-submittable state.

Dave?
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