lkml.org 
[lkml]   [2009]   [Mar]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 00/35] Cleanup and optimise the page allocator V3
On Mon, Mar 16, 2009 at 06:05:51PM +0100, Nick Piggin wrote:
> On Mon, Mar 16, 2009 at 04:56:28PM +0000, Mel Gorman wrote:
> > On Mon, Mar 16, 2009 at 04:53:42PM +0100, Nick Piggin wrote:
> > > So yes definitely I think there should be a very real impact on
> > > higher order coalescing no matter what you do.
> > >
> >
> > Because this is not straight-forward at all, I'll put lazy buddy onto
> > the back-burner and exhaust all other possibilities before revisiting it
> > again.
>
> If it is such a big improvement, I expect *most* people will want
> it and we probably should do it.

I'll be reinvestigating it in isolation. It's possible that high-order and
compound pages on the PCP lists is enough of a delayed buddy merging that
the benefit from lazy buddy is marginal.

> But just that it will not play
> nicely with fragmentation and so you'd need to look into it and
> devise some way those users can tune it to be nicer.
>

Which is why I'm going to postpone it for now.

> > > unmovable zone fragmentation is more important point because it
> > > eventually can destroy the movable zone.
> > >
> >
> > Which is why rmqueue_fallback() also merges up all buddies before making
> > any decisions but I accept your points.
>
> Right, that merge of buddies will only be able to look at what is
> currently free. Wheras non-lazy buddy can pull out higher orders
> before reallocating them.
>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


\
 
 \ /
  Last update: 2009-03-18 16:09    [W:0.099 / U:0.580 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site