Re: large page patch (fwd) (fwd)

Daniel Phillips
2002-08-09T16:14:13Z

On Friday 09 August 2002 17:56, Linus Torvalds wrote:
> On Fri, 9 Aug 2002, Daniel Phillips wrote:
> > This reference describes roughly what I had in mind for active
> > defragmentation, which depends on reverse mapping.
>
> 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.

> Not unless you think I am crazy enough to do garbage collection on kernel
> data structures (repeat after me: "garbage collection is stupid, slow, bad
> for caches, and only for people who cannot count").

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

> Also, I think the jury (ie Andrew) is still out on whether rmap is worth
> it.

Tell me about it. Well, I feel strongly enough about it to spend the next
week coding yet another pte chain optimization.

--
Daniel