From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 2/2] KVM: Use the scheduler preemption hooks to make kvm preemptible Date: Thu, 12 Jul 2007 08:43:08 +0300 Message-ID: <4695BF6C.9000501@qumranet.com> References: <11841693332609-git-send-email-avi@qumranet.com> <1184169333786-git-send-email-avi@qumranet.com> <68676e00707111310v4862974am37dc7c723486b96c@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Luca Return-path: In-Reply-To: <68676e00707111310v4862974am37dc7c723486b96c-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Luca wrote: > On 7/11/07, Avi Kivity wrote: >> Current kvm disables preemption while the new virtualization >> registers are >> in use. This of course is not very good for latency sensitive >> workloads (one >> use of virtualization is to offload user interface and other latency >> insensitive stuff to a container, so that it is easier to analyze the >> remaining workload). This patch re-enables preemption for kvm; >> preemption >> is now only disabled when switching the registers in and out, and during >> the switch to guest mode and back. > [...] >> diff --git a/drivers/kvm/Kconfig b/drivers/kvm/Kconfig >> index 33fa28a..92644b5 100644 >> --- a/drivers/kvm/Kconfig >> +++ b/drivers/kvm/Kconfig >> @@ -10,7 +10,7 @@ if VIRTUALIZATION >> >> config KVM >> tristate "Kernel-based Virtual Machine (KVM) support" >> - depends on X86 && EXPERIMENTAL >> + depends on X86 && EXPERIMENTAL && PREEMPT_HOOKS >> depends on X86_CMPXCHG64 || 64BIT > > select PREEMPT_HOOKS maybe? > Yes. And default PREEMPT_HOOKS to n in the first patch. I'll make both these changes. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/