From: David Gibson <david@gibson.dropbear.id.au>
To: Andi Kleen <ak@suse.de>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org,
benh@kernel.crashing.org, anton@samba.org, paulus@samba.org,
linuxppc64-dev@lists.linuxppc.org
Subject: Re: RFC: COW for hugepages
Date: Thu, 8 Apr 2004 11:50:43 +1000 [thread overview]
Message-ID: <20040408015043.GA20320@zax> (raw)
In-Reply-To: <20040407143447.4d8f08af.ak@suse.de>
On Wed, Apr 07, 2004 at 02:34:47PM +0200, Andi Kleen wrote:
> On Wed, 7 Apr 2004 17:42:39 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
>
> > Currently the kernel does not implement copy-on-write for huge pages -
> > in fact any sort of page fault on a hugepage results in a SIGBUS.
> > This means that hugepages *always* have MAP_SHARED semantics, even if
> > MAP_PRIVATE is requested, and in particular that they are always
> > shared across a fork(). Particularly when using hugetlbfs as just a
> > source of quasi-anonymous memory, those are rather strange semantics.
>
> [...]
>
> Implementing this for ppc64 only is just wrong. Before you do this
> I would suggest to factor out the common code in the various hugetlbpage
> implementations and then implement it in common code.
Yes, I know it needs to be implemented for the other archs, but I
wanted to get some feedback on the concept before diving into the
other arch details to figure out how to implement it there.
--
David Gibson | For every complex problem there is a
david AT gibson.dropbear.id.au | solution which is simple, neat and
| wrong.
http://www.ozlabs.org/people/dgibson
next prev parent reply other threads:[~2004-04-08 1:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-07 7:42 David Gibson
2004-04-07 7:53 ` Andrew Morton
2004-04-07 8:03 ` Anton Blanchard
2004-04-07 8:29 ` Benjamin Herrenschmidt
2004-04-08 1:57 ` David Gibson
2004-04-07 9:00 ` Zoltan Menyhart
2004-04-08 1:53 ` David Gibson
2004-04-08 11:10 ` Zoltan Menyhart
2004-04-08 14:19 ` David Gibson
2004-04-07 12:34 ` Andi Kleen
2004-04-07 14:27 ` Anton Blanchard
2004-04-07 14:50 ` Andi Kleen
2004-04-07 21:41 ` Anton Blanchard
2004-04-07 21:47 ` Andi Kleen
2004-04-08 1:11 ` Benjamin Herrenschmidt
2004-04-08 2:01 ` Andrew Morton
2004-04-08 3:09 ` David Gibson
2004-04-08 3:24 ` Andrew Morton
2004-04-08 3:56 ` David Gibson
2004-04-08 1:50 ` David Gibson [this message]
2004-04-07 15:21 ` Dave Hansen
2004-04-08 3:22 ` David Gibson
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