Re: [patch] mm: unlockless reclaim

[Nick Piggin <npiggin@suse.de>]

On Thu, Jul 12, 2007 at 01:00:07AM -0700, Andrew Morton wrote:
> On Thu, 12 Jul 2007 09:55:32 +0200 Nick Piggin <npiggin@suse.de> wrote:
> 
> > > 
> > > mutter.
> > > 
> > > So why does __pagevec_release_nonlru() check the page refcount?
> > 
> > It doesn't
> 
> yes it does

That was in answer to your question: I mean: it doesn't need to.


> > although it will have to return the count to zero of course.
> > 
> > I don't want to submit that because the lockless pagecache always needs
> > the refcount to be checked :) And which I am actually going to submit to
> > you after you chuck out a few patches.
> > 
> > But unlock_page is really murderous on my powerpc (with all the
> > unlock-speeup patches, dd if=/dev/zero of=/dev/null of a huge sparse file
> > goes up by 10% throughput on the G5!!).
> 
> well this change won't help that much.

Oh, well the dd includes reclaim and so it ends up doing 2 locks for
each page (1 to reading, 1 to reclaim). So this alone supposedly should
help by 5% :)


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