Re: large page patch (fwd) (fwd)

Linus Torvalds
2002-08-09T17:00:24Z

On Fri, 9 Aug 2002, Daniel Phillips wrote:
> >
> > Note that even active defrag won't be able to handle the case where you
> > want have lots of big pages, consituting a large percentage of available
> > memory.
>
> Perhaps I'm missing something, but I don't see why.

The statistics are against you. rmap won't help at all with all the other
kernel allocations, and the dcache/icache is often large, and on big
machines while there may be tens of thousands of idle entries, there will
also be hundreds of _non_idle entries that you can't just remove.

> Slab allocations would not have GFP_DEFRAG (I mistakenly wrote GFP_LARGE
> earlier) and so would be allocated outside ZONE_LARGE.

.. at which poin tyou then get zone balancing problems.

Or we end up with the same kind of special zone that we have _anyway_ in
the current large-page patch, in which case the point of doing this is
what?

Linus