From: Andrew Morton <akpm@linux-foundation.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>,
linux-mm@kvack.org, Mel Gorman <mel@csn.ul.ie>
Subject: Re: [patch 0/3] Hotcold removal completion
Date: Mon, 11 Feb 2008 23:57:14 -0800 [thread overview]
Message-ID: <20080211235714.1484b0c7.akpm@linux-foundation.org> (raw)
In-Reply-To: <200802121732.29593.nickpiggin@yahoo.com.au>
On Tue, 12 Feb 2008 17:32:29 +1100 Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> On Tuesday 12 February 2008 11:36, Christoph Lameter wrote:
> > The patch that we had in mm for the removal of the cold page queue was
> > merged.
>
> That patch to merge the hot and cold lists has obvious problems.
> It pulls cold pages off the list in the opposite order that hot
> pages come off the list (which is obviously bad); and also it
> allows cold allocations to deplete hot pages (which may not be a
> good idea).
>
> Obviously the half baked code that's there now should be fixed...
> But whether it is to fix hot/cold properly, or to remove it
> completely, I don't really know.
>
Well that sounds bad.
>
> > However, there were 3 more pages that I think are necessary to
> > complete the work. Mel's testing indicated that the patch in mm is inferior
> > to simply removing the hot cold distinction in the VM altogether
> > (see http://marc.info/?t=119507025400001&r=1&w=2).
> >
> > These 3 patches get rid of cold page handling in the VM.
>
> I'm all in favour of removing these. But honestly, I don't think
> kernbench, [td]bench, and aim9 are really great tests when it
> comes to subtle cache behaviour... OTOH, that didn't stop the
> last patch being merged. May as well do it.
I think I'd prefer that we convince ourselves that we didn't just merge a
regression rather than merging more stuff on top of it. Because right now,
page-allocator-get-rid-of-the-list-of-cold-pages.patch reverts cleanly.
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next prev parent reply other threads:[~2008-02-12 7:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-12 0:36 [patch 0/3] Hotcold removal completion Christoph Lameter
2008-02-12 0:36 ` [patch 1/3] Eliminate the hot/cold distinction in the page allocator Christoph Lameter
2008-02-12 0:36 ` [patch 2/3] Remove GFP_COLD Christoph Lameter
2008-02-12 0:36 ` [patch 3/3] Remove cold field from pagevec Christoph Lameter
2008-02-12 6:32 ` [patch 0/3] Hotcold removal completion Nick Piggin
2008-02-12 7:57 ` Andrew Morton [this message]
2008-02-12 20:12 ` Christoph Lameter
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