Re: [PATCH 4/10] alternate 4-level page tables patches

[Andi Kleen <ak@suse.de>]

On Sat, Dec 18, 2004 at 08:05:26PM +1100, Nick Piggin wrote:
> Nick Piggin wrote:
> >4/10
> >
> >
> >------------------------------------------------------------------------
> >
> >
> >
> >Rename clear_page_tables to clear_page_range. clear_page_range takes byte
> >ranges, and aggressively frees page table pages. Maybe useful to control
> >page table memory consumption on 4-level architectures (and even 3 level
> >ones).
> >
> 
> I maybe didn't do this patch justice by hiding it away in this series.
> It may be worthy of its own thread - surely there must be some significant
> downsides if nobody had implemented it in the past (or maybe just a fact
> of "that doesn't happen much").

Yes, more could be done in this area. When I did 4level I just tried
to keep the same semantics without optimizing anything.

Another way I thought about was to have a reference count of the used
ptes/pmds per page table page in struct page and free the page when it goes 
to zero. That would give perfect garbage collection. Drawback is that
it may be a bit intrusive again.

-Andi

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"aart@kvack.org"> aart@kvack.org </a>