From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options. Date: Fri, 16 Feb 2007 11:03:06 +0000 Message-ID: References: <20070216025452.d25e3545.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20070216025452.d25e3545.akpm@linux-foundation.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.osdl.org Errors-To: virtualization-bounces@lists.osdl.org To: Andrew Morton , Keir Fraser Cc: Chris Wright , Andi Kleen , xen-devel@lists.xensource.com, virtualization@lists.osdl.org, linux-kernel@vger.kernel.org, Steven Hand , Ian Pratt , Christian Limpach List-Id: virtualization@lists.linuxfoundation.org On 16/2/07 10:54, "Andrew Morton" wrote: > OK, you're screwed. I agree that the process freezer is the way out of t= hat > 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