From: Nick Piggin <npiggin@suse.de>
To: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
avi@redhat.com, akpm@linux-foundation.org,
torvalds@linux-foundation.org
Subject: Re: [RFC][PATCH 0/4] ZERO PAGE again v2
Date: Mon, 13 Jul 2009 08:46:41 +0200 [thread overview]
Message-ID: <20090713064641.GL14666@wotan.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0907101201280.2456@sister.anvils>
On Fri, Jul 10, 2009 at 12:18:07PM +0100, Hugh Dickins wrote:
> On Wed, 8 Jul 2009, Andrea Arcangeli wrote:
> > On Tue, Jul 07, 2009 at 06:06:29PM +0900, KAMEZAWA Hiroyuki wrote:
> > harmful as there's a double page fault generated instead of a single
> > one, kksmd has a cost but zeropage isn't free either in term of page
> > faults too)
>
> Much as I like KSM, I have to agree with Avi, that if people are
> wanting the ZERO_PAGE back in compute-intensive loads, then relying
I can't imagine ZERO_PAGE would be too widely used in compute-intensive
loads. At least, not serious stuff. Nobody wants to spend 4K of cache
and one TLB entry for one or two non-zero floating point numbers in a
big sparse matrix. Not to mention the cache and memory overhead of just
scanning through lots of zeros.
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next prev parent reply other threads:[~2009-07-13 6:25 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-07 7:51 [RFC][PATCH 0/4] ZERO PAGE again v2 KAMEZAWA Hiroyuki
2009-07-07 7:52 ` [RFC][PATCH 1/4] introduce pte_zero() KAMEZAWA Hiroyuki
2009-07-07 7:54 ` [RFC][PATCH 2/4] use ZERO_PAGE for READ fault in regular anonymous mapping KAMEZAWA Hiroyuki
2009-07-07 7:59 ` [RFC][PATCH 3/4] get_user_pages READ fault handling special cases KAMEZAWA Hiroyuki
2009-07-07 16:50 ` Linus Torvalds
2009-07-08 0:03 ` KAMEZAWA Hiroyuki
2009-07-08 1:38 ` KAMEZAWA Hiroyuki
2009-07-08 2:27 ` Linus Torvalds
2009-07-07 8:01 ` [RFC][PATCH 4/4] add get user pages nozero KAMEZAWA Hiroyuki
2009-07-07 8:47 ` [RFC][PATCH 0/4] ZERO PAGE again v2 Nick Piggin
2009-07-07 9:05 ` Avi Kivity
2009-07-07 9:18 ` KAMEZAWA Hiroyuki
2009-07-07 9:26 ` Avi Kivity
2009-07-07 9:06 ` KAMEZAWA Hiroyuki
2009-07-07 14:00 ` Nick Piggin
2009-07-07 16:59 ` Linus Torvalds
2009-07-08 6:21 ` Nick Piggin
2009-07-08 16:07 ` Linus Torvalds
2009-07-09 7:47 ` Nick Piggin
2009-07-09 17:54 ` Linus Torvalds
2009-07-10 2:09 ` Nick Piggin
2009-07-10 3:38 ` Linus Torvalds
2009-07-10 3:51 ` Nick Piggin
2009-07-08 17:32 ` Andrea Arcangeli
2009-07-09 1:12 ` KAMEZAWA Hiroyuki
2009-07-10 11:18 ` Hugh Dickins
2009-07-10 13:42 ` Andrea Arcangeli
2009-07-10 14:12 ` KAMEZAWA Hiroyuki
2009-07-10 15:16 ` Andrea Arcangeli
2009-07-10 15:32 ` KAMEZAWA Hiroyuki
2009-07-10 17:09 ` Hugh Dickins
2009-07-13 6:46 ` Nick Piggin [this message]
2009-07-13 7:24 ` Nick Piggin
-- strict thread matches above, loose matches on Subject: below --
2009-07-07 15:50 KAMEZAWA Hiroyuki
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