From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-mm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [QUICKLIST 0/4] Arch independent quicklists V2
Date: Tue, 13 Mar 2007 04:27:42 -0800 [thread overview]
Message-ID: <20070313042742.e35b7511.akpm@linux-foundation.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0703130413080.5720@schroedinger.engr.sgi.com>
> On Tue, 13 Mar 2007 04:17:26 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:
> On Tue, 13 Mar 2007, Andrew Morton wrote:
>
> > > On Tue, 13 Mar 2007 00:13:25 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:
> > > Page table pages have the characteristics that they are typically zero
> > > or in a known state when they are freed.
> >
> > Well if they're zero then perhaps they should be released to the page
> > allocator to satisfy the next __GFP_ZERO request. If that request is
> > for a pagetable page, we break even (except we get to remove
> > special-case code). If that __GFP_ZERO allocation was or some
> > application other than for a pagetable, we win.
>
> Nope that wont work.
>
> 1. We need to support other states of pages other than zeroed.
What does this mean?
> 2. Prezeroing does not make much sense if a large portion of the
> page is being used. Performance is better if the whole page
> is zeroed directly before use.Prezeroing only makes sense for sparse
> allocations like the page table pages.
This is not related to the above discussion.
> > (Will require some work in the page allocator)
> > (That work will open the path to using the idle thread to prezero pages)
>
> I already tried that 3 years ago and there was *no* benefit for usual
> users of the a page allocator. The advantage exists only if a small
> portion of the page is used. F.e. For one cacheline there was a 4x
> improvement. See lkml archives for prezeroing.
Unsurprised. Were non-temporal stores tried?
next prev parent reply other threads:[~2007-03-13 11:27 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-13 7:13 [QUICKLIST 0/4] Arch independent quicklists V2 Christoph Lameter
2007-03-13 7:13 ` [QUICKLIST 1/4] Generic quicklist implementation Christoph Lameter
2007-03-13 9:05 ` Paul Mundt
2007-03-15 20:51 ` Christoph Lameter
2007-03-13 7:13 ` [QUICKLIST 2/4] Quicklist support for i386 Christoph Lameter
2007-03-13 7:13 ` [QUICKLIST 3/4] Quicklist support for x86_64 Christoph Lameter
2007-03-13 7:13 ` [QUICKLIST 4/4] Quicklist support for sparc64 Christoph Lameter
2007-03-13 8:53 ` [QUICKLIST 0/4] Arch independent quicklists V2 Andrew Morton
2007-03-13 8:03 ` Nick Piggin
2007-03-13 11:52 ` Andrew Morton
2007-03-13 11:06 ` Nick Piggin
2007-03-13 12:15 ` Andrew Morton
2007-03-13 11:20 ` Christoph Lameter
2007-03-13 12:30 ` Andrew Morton
2007-03-15 20:23 ` Christoph Lameter
2007-03-13 11:30 ` Nick Piggin
2007-03-13 12:47 ` Andrew Morton
2007-03-13 12:01 ` Nick Piggin
2007-03-13 13:11 ` Andrew Morton
2007-03-13 12:18 ` Nick Piggin
2007-03-13 17:30 ` Jeremy Fitzhardinge
2007-03-13 20:03 ` Matt Mackall
2007-03-13 20:17 ` Jeremy Fitzhardinge
2007-03-13 20:21 ` Matt Mackall
2007-03-13 21:07 ` David Miller
2007-03-13 21:14 ` Matt Mackall
2007-03-13 21:36 ` Jeremy Fitzhardinge
2007-03-13 21:46 ` Peter Chubb
2007-03-13 21:48 ` David Miller
2007-03-14 1:12 ` William Lee Irwin III
2007-03-15 23:12 ` William Lee Irwin III
2007-03-13 23:58 ` Paul Mackerras
2007-03-13 11:17 ` Christoph Lameter
2007-03-13 12:27 ` Andrew Morton [this message]
2007-03-15 20:28 ` Christoph Lameter
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