Re: VM fixes [2/4]

[Andrea Arcangeli <andrea@suse.de>]

On Fri, Dec 31, 2004 at 08:12:42AM +1100, Nick Piggin wrote:
> Andrea Arcangeli wrote:
> >This is the forward port to 2.6 of the lowmem_reserved algorithm I
> >invented in 2.4.1*, merged in 2.4.2x already and needed to fix workloads
> >like google (especially without swap) on x86 with >1G of ram, but it's
> >needed in all sort of workloads with lots of ram on x86, it's also
> >needed on x86-64 for dma allocations. This brings 2.6 in sync with
> >latest 2.4.2x.
> >
> 
> This looks OK to me. It really simplifies the code there a lot too.
> 
> The only questions I have are: should it be on by default? I don't think
> we ever reached an agreement. I'd say yes, after a run in -mm because it
> does potentially fix corner cases where lower zones get filled with un-
> freeable memory which could have been satisfied with higher zones.

Great, thanks for the review! I definitely agree it should be on by
default, I already had an hang report that was solved by more recent
kernels and that probably can only be explained by lowmem_reserve since
there aren't other mm changes in 2.6.5 based trees. 

> And second, any chance you could you port it to the mm patches already in
> -mm? Won't be a big job, just some clashes in __alloc_pages...

I already had to port to 2.6.5 too, and that's enough for now unless I
first get a positive ack that it will be merged (if I hadn't more
interesting things to develop, I would be happily porting it).