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From: Keir Fraser <keir@xensource.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Keir Fraser <keir@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>, Andi Kleen <ak@muc.de>,
	<xen-devel@lists.xensource.com>,
	Ian Pratt <Ian.Pratt@xensource.com>,
	<virtualization@lists.osdl.org>,
	Steven Hand <steven.hand@cl.cam.ac.uk>,
	Christian Limpach <Christian.Limpach@xensource.com>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options.
Date: Fri, 16 Feb 2007 11:03:06 +0000	[thread overview]
Message-ID: <C1FB3FEA.98F7%keir@xensource.com> (raw)
In-Reply-To: <20070216025452.d25e3545.akpm@linux-foundation.org>

On 16/2/07 10:54, "Andrew Morton" <akpm@linux-foundation.org> wrote:

> OK, you're screwed.  I agree that the process freezer is the way out of that
> one.
> 
> Ingo said that he's clocked the freezer at a few milliseconds.  But if it's
> any higher than that it'll need to get sped up once we convert cpu hotplug
> to use it.

A few milliseconds is acceptable. Presumably that is under some stress
workload? What we'd really like is to be able to gang-hotplug CPUs to
amortise the freezer overhead.

This initial patchset does not include save/restore support anyway, so in
fact it would be consistent to have CONFIG_PREEMPT configurable. I'm sure
that we are going to have some nasty bugs to fix up as a result, but we
can't fix them until we find them! Then we can convert our save/restore code
to use the freezer before submitting it for inclusion.

 -- Keir


WARNING: multiple messages have this Message-ID
From: Keir Fraser <keir@xensource.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Keir Fraser <keir@xensource.com>
Cc: xen-devel@lists.xensource.com, virtualization@lists.osdl.org,
	linux-kernel@vger.kernel.org,
	Christian Limpach <Christian.Limpach@xensource.com>,
	Chris Wright <chrisw@sous-sol.org>, Andi Kleen <ak@muc.de>,
	Steven Hand <steven.hand@cl.cam.ac.uk>,
	Ian Pratt <Ian.Pratt@xensource.com>
Subject: Re: [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options.
Date: Fri, 16 Feb 2007 11:03:06 +0000	[thread overview]
Message-ID: <C1FB3FEA.98F7%keir@xensource.com> (raw)
In-Reply-To: <20070216025452.d25e3545.akpm@linux-foundation.org>

On 16/2/07 10:54, "Andrew Morton" <akpm@linux-foundation.org> wrote:

> OK, you're screwed.  I agree that the process freezer is the way out of that
> one.
> 
> Ingo said that he's clocked the freezer at a few milliseconds.  But if it's
> any higher than that it'll need to get sped up once we convert cpu hotplug
> to use it.

A few milliseconds is acceptable. Presumably that is under some stress
workload? What we'd really like is to be able to gang-hotplug CPUs to
amortise the freezer overhead.

This initial patchset does not include save/restore support anyway, so in
fact it would be consistent to have CONFIG_PREEMPT configurable. I'm sure
that we are going to have some nasty bugs to fix up as a result, but we
can't fix them until we find them! Then we can convert our save/restore code
to use the freezer before submitting it for inclusion.

 -- Keir

  parent reply	other threads:[~2007-02-16 11:03 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-16 10:00 [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options Christian Limpach
2007-02-16 10:00 ` Christian Limpach
2007-02-16 10:09 ` Andrew Morton
2007-02-16 10:09   ` Andrew Morton
2007-02-16 10:47   ` Keir Fraser
2007-02-16 10:47   ` Keir Fraser
2007-02-16 10:47     ` Keir Fraser
2007-02-16 10:54     ` Andrew Morton
2007-02-16 10:54       ` Andrew Morton
2007-02-16 11:03       ` Keir Fraser
2007-02-16 11:03       ` Keir Fraser [this message]
2007-02-16 11:03         ` Keir Fraser
2007-02-16 17:46         ` [Xen-devel] " Jeremy Fitzhardinge
2007-02-16 17:46           ` Jeremy Fitzhardinge
2007-02-16 19:00           ` [Xen-devel] " Keir Fraser
2007-02-16 19:00           ` Keir Fraser
2007-02-16 19:00             ` Keir Fraser
2007-02-16 19:24             ` [Xen-devel] " Jeremy Fitzhardinge
2007-02-16 19:24               ` Jeremy Fitzhardinge
2007-02-16 21:51             ` [Xen-devel] " Zachary Amsden
2007-02-16 21:51               ` Zachary Amsden
2007-02-16 22:38               ` [Xen-devel] " Dan Hecht
2007-02-17 15:06                 ` Rik van Riel
2007-02-17 15:06                   ` Rik van Riel
2007-02-16 19:00           ` [Xen-devel] " Keir Fraser
2007-02-16 11:03       ` Keir Fraser
2007-02-16 10:47   ` Keir Fraser

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