From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [Xen-devel] [PATCH 0/9] qspinlock stuff -v15 Date: Mon, 16 Mar 2015 14:08:58 +0000 Message-ID: <5506E3FA.7040304@citrix.com> References: <20150316131613.720617163@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150316131613.720617163@infradead.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Peter Zijlstra , Waiman.Long@hp.com Cc: linux-arch@vger.kernel.org, riel@redhat.com, x86@kernel.org, kvm@vger.kernel.org, oleg@redhat.com, scott.norton@hp.com, raghavendra.kt@linux.vnet.ibm.com, paolo.bonzini@gmail.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, mingo@redhat.com, doug.hatch@hp.com, hpa@zytor.com, luto@amacapital.net, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, paulmck@linux.vnet.ibm.com, torvalds@linux-foundation.org, tglx@linutronix.de, david.vrabel@citrix.com List-Id: linux-arch.vger.kernel.org On 16/03/15 13:16, Peter Zijlstra wrote: > Hi Waiman, > > As promised; here is the paravirt stuff I did during the trip to BOS last week. > > All the !paravirt patches are more or less the same as before (the only real > change is the copyright lines in the first patch). > > The paravirt stuff is 'simple' and KVM only -- the Xen code was a little more > convoluted and I've no real way to test that but it should be stright fwd to > make work. > > I ran this using the virtme tool (thanks Andy) on my laptop with a 4x > overcommit on vcpus (16 vcpus as compared to the 4 my laptop actually has) and > it both booted and survived a hackbench run (perf bench sched messaging -g 20 > -l 5000). > > So while the paravirt code isn't the most optimal code ever conceived it does work. > > Also, the paravirt patching includes replacing the call with "movb $0, %arg1" > for the native case, which should greatly reduce the cost of having > CONFIG_PARAVIRT_SPINLOCKS enabled on actual hardware. > > I feel that if someone were to do a Xen patch we can go ahead and merge this > stuff (finally!). I can look at this. It looks pretty straight-forward. > These patches do not implement the paravirt spinlock debug stats currently > implemented (separately) by KVM and Xen, but that should not be too hard to do > on top and in the 'generic' code -- no reason to duplicate all that. I think this is fine. David From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.citrix.com ([66.165.176.89]:48430 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754448AbbCPOJL (ORCPT ); Mon, 16 Mar 2015 10:09:11 -0400 Message-ID: <5506E3FA.7040304@citrix.com> Date: Mon, 16 Mar 2015 14:08:58 +0000 From: David Vrabel MIME-Version: 1.0 Subject: Re: [Xen-devel] [PATCH 0/9] qspinlock stuff -v15 References: <20150316131613.720617163@infradead.org> In-Reply-To: <20150316131613.720617163@infradead.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra , Waiman.Long@hp.com Cc: raghavendra.kt@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, boris.ostrovsky@oracle.com, linux-arch@vger.kernel.org, x86@kernel.org, mingo@redhat.com, doug.hatch@hp.com, xen-devel@lists.xenproject.org, paulmck@linux.vnet.ibm.com, riel@redhat.com, scott.norton@hp.com, paolo.bonzini@gmail.com, tglx@linutronix.de, virtualization@lists.linux-foundation.org, oleg@redhat.com, luto@amacapital.net, david.vrabel@citrix.com, torvalds@linux-foundation.org Message-ID: <20150316140858.eb_4cnCYkIpLPL_oO8D6bapXLvQykD3zIzSZ1llv9aQ@z> On 16/03/15 13:16, Peter Zijlstra wrote: > Hi Waiman, > > As promised; here is the paravirt stuff I did during the trip to BOS last week. > > All the !paravirt patches are more or less the same as before (the only real > change is the copyright lines in the first patch). > > The paravirt stuff is 'simple' and KVM only -- the Xen code was a little more > convoluted and I've no real way to test that but it should be stright fwd to > make work. > > I ran this using the virtme tool (thanks Andy) on my laptop with a 4x > overcommit on vcpus (16 vcpus as compared to the 4 my laptop actually has) and > it both booted and survived a hackbench run (perf bench sched messaging -g 20 > -l 5000). > > So while the paravirt code isn't the most optimal code ever conceived it does work. > > Also, the paravirt patching includes replacing the call with "movb $0, %arg1" > for the native case, which should greatly reduce the cost of having > CONFIG_PARAVIRT_SPINLOCKS enabled on actual hardware. > > I feel that if someone were to do a Xen patch we can go ahead and merge this > stuff (finally!). I can look at this. It looks pretty straight-forward. > These patches do not implement the paravirt spinlock debug stats currently > implemented (separately) by KVM and Xen, but that should not be too hard to do > on top and in the 'generic' code -- no reason to duplicate all that. I think this is fine. David