From: Linus Torvalds <torvalds@linux-foundation.org>
To: Balbir Singh <balbir@in.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@skynet.ie>,
npiggin@suse.de, clameter@engr.sgi.com, mingo@elte.hu,
jschopp@austin.ibm.com, arjan@infradead.org, mbligh@mbligh.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: The performance and behaviour of the anti-fragmentation related patches
Date: Thu, 1 Mar 2007 19:44:27 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.64.0703011939120.12485@woody.linux-foundation.org> (raw)
In-Reply-To: <45E7835A.8000908@in.ibm.com>
On Fri, 2 Mar 2007, Balbir Singh wrote:
>
> > My personal opinion is that while I'm not a huge fan of virtualization,
> > these kinds of things really _can_ be handled more cleanly at that layer,
> > and not in the kernel at all. Afaik, it's what IBM already does, and has
> > been doing for a while. There's no shame in looking at what already works,
> > especially if it's simpler.
>
> Could you please clarify as to what "that layer" means - is it the
> firmware/hardware for virtualization? or does it refer to user space?
Virtualization in general. We don't know what it is - in IBM machines it's
a hypervisor. With Xen and VMware, it's usually a hypervisor too. With
KVM, it's obviously a host Linux kernel/user-process combination.
The point being that in the guests, hotunplug is almost useless (for
bigger ranges), and we're much better off just telling the virtualization
hosts on a per-page level whether we care about a page or not, than to
worry about fragmentation.
And in hosts, we usually don't care EITHER, since it's usually done in a
hypervisor.
> It would also be useful to have a resource controller like per-container
> RSS control (container refers to a task grouping) within the kernel or
> non-virtualized environments as well.
.. but this has again no impact on anti-fragmentation.
In other words, I really don't see a huge upside. I see *lots* of
downsides, but upsides? Not so much. Almost everybody who wants unplug
wants virtualization, and right now none of the "big virtualization"
people would want to have kernel-level anti-fragmentation anyway sicne
they'd need to do it on their own.
Linus
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next prev parent reply other threads:[~2007-03-02 3:44 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-01 10:12 The performance and behaviour of the anti-fragmentation related patches Mel Gorman
2007-03-02 0:09 ` Andrew Morton
2007-03-02 0:44 ` Linus Torvalds
2007-03-02 1:52 ` Balbir Singh
2007-03-02 3:44 ` Linus Torvalds [this message]
2007-03-02 3:59 ` Andrew Morton
2007-03-02 5:11 ` Linus Torvalds
2007-03-02 5:50 ` KAMEZAWA Hiroyuki
2007-03-02 6:15 ` Paul Mundt
2007-03-02 17:01 ` Mel Gorman
2007-03-02 16:20 ` Mark Gross
2007-03-02 17:07 ` Andrew Morton
2007-03-02 17:35 ` Mark Gross
2007-03-02 18:02 ` Andrew Morton
2007-03-02 19:02 ` Mark Gross
2007-03-02 17:16 ` Linus Torvalds
2007-03-02 18:45 ` Mark Gross
2007-03-02 19:03 ` Linus Torvalds
2007-03-02 23:58 ` Martin J. Bligh
2007-03-02 4:18 ` Balbir Singh
2007-03-02 5:13 ` Jeremy Fitzhardinge
2007-03-06 4:16 ` Paul Mackerras
2007-03-02 16:58 ` Mel Gorman
2007-03-02 17:05 ` Joel Schopp
2007-03-05 3:21 ` Nick Piggin
2007-03-05 15:20 ` Joel Schopp
2007-03-05 16:01 ` Nick Piggin
2007-03-05 16:45 ` Joel Schopp
2007-05-03 8:49 ` Andy Whitcroft
2007-03-02 1:39 ` Balbir Singh
2007-03-02 2:34 ` KAMEZAWA Hiroyuki
2007-03-02 3:05 ` Christoph Lameter
2007-03-02 3:57 ` Nick Piggin
2007-03-02 4:06 ` Christoph Lameter
2007-03-02 4:21 ` Nick Piggin
2007-03-02 4:31 ` Christoph Lameter
2007-03-02 5:06 ` Nick Piggin
2007-03-02 5:40 ` Christoph Lameter
2007-03-02 5:49 ` Nick Piggin
2007-03-02 5:53 ` Christoph Lameter
2007-03-02 6:08 ` Nick Piggin
2007-03-02 6:19 ` Christoph Lameter
2007-03-02 6:29 ` Nick Piggin
2007-03-02 6:51 ` Christoph Lameter
2007-03-02 7:03 ` Andrew Morton
2007-03-02 7:19 ` Nick Piggin
2007-03-02 7:44 ` Christoph Lameter
2007-03-02 8:12 ` Nick Piggin
2007-03-02 8:21 ` Christoph Lameter
2007-03-02 8:38 ` Nick Piggin
2007-03-02 17:09 ` Christoph Lameter
2007-03-04 1:26 ` Rik van Riel
2007-03-04 1:51 ` Andrew Morton
2007-03-04 1:58 ` Rik van Riel
2007-03-02 5:50 ` Christoph Lameter
2007-03-02 4:29 ` Andrew Morton
2007-03-02 4:33 ` Christoph Lameter
2007-03-02 4:58 ` Andrew Morton
2007-03-02 4:20 ` Paul Mundt
2007-03-02 13:50 ` Arjan van de Ven
2007-03-02 15:29 ` Rik van Riel
2007-03-02 16:58 ` Andrew Morton
2007-03-02 17:09 ` Mel Gorman
2007-03-02 17:23 ` Christoph Lameter
2007-03-02 17:35 ` Andrew Morton
2007-03-02 17:43 ` Rik van Riel
2007-03-02 18:06 ` Andrew Morton
2007-03-02 18:15 ` Christoph Lameter
2007-03-02 18:23 ` Andrew Morton
2007-03-02 18:23 ` Rik van Riel
2007-03-02 19:31 ` Christoph Lameter
2007-03-02 19:40 ` Rik van Riel
2007-03-02 21:12 ` Bill Irwin
2007-03-02 21:19 ` Rik van Riel
2007-03-02 21:52 ` Andrew Morton
2007-03-02 22:03 ` Rik van Riel
2007-03-02 22:22 ` Andrew Morton
2007-03-02 22:34 ` Rik van Riel
2007-03-02 22:51 ` Martin Bligh
2007-03-02 22:54 ` Rik van Riel
2007-03-02 23:28 ` Martin J. Bligh
2007-03-03 0:24 ` Andrew Morton
2007-03-02 22:52 ` Chuck Ebbert
2007-03-02 22:59 ` Andrew Morton
2007-03-02 23:20 ` Rik van Riel
2007-03-03 1:40 ` William Lee Irwin III
2007-03-03 1:58 ` Andrew Morton
2007-03-03 3:55 ` William Lee Irwin III
2007-03-03 0:33 ` William Lee Irwin III
2007-03-03 0:54 ` Andrew Morton
2007-03-03 3:15 ` Christoph Lameter
2007-03-03 4:19 ` William Lee Irwin III
2007-03-03 17:16 ` Martin J. Bligh
2007-03-03 17:50 ` Christoph Lameter
2007-03-02 20:59 ` Bill Irwin
2007-03-02 1:52 ` Bill Irwin
2007-03-02 10:38 ` Mel Gorman
2007-03-02 16:31 ` Joel Schopp
2007-03-02 21:37 ` Bill Irwin
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