From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH RFC V9 0/19] Paravirtualized ticket spinlocks Date: Wed, 10 Jul 2013 13:47:17 +0300 Message-ID: <20130710104717.GR24941@redhat.com> References: <1372171802.3804.30.camel@oc2024037011.ibm.com> <51CAAA26.4090204@linux.vnet.ibm.com> <20130626113744.GA6300@hawk.usersys.redhat.com> <20130626125240.GY18508@redhat.com> <51CAEF45.3010203@linux.vnet.ibm.com> <20130626161130.GB18152@redhat.com> <51CB2AD9.5060508@linux.vnet.ibm.com> <51DBD3C2.2040807@linux.vnet.ibm.com> <20130710103325.GP24941@redhat.com> <20130710104047.GP25631@dyad.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20130710104047.GP25631@dyad.programming.kicks-ass.net> 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 Cc: jeremy@goop.org, Raghavendra K T , kvm@vger.kernel.org, linux-doc@vger.kernel.org, riel@redhat.com, virtualization@lists.linux-foundation.org, andi@firstfloor.org, hpa@zytor.com, stefano.stabellini@eu.citrix.com, xen-devel@lists.xensource.com, x86@kernel.org, mingo@redhat.com, habanero@linux.vnet.ibm.com, Andrew Jones , konrad.wilk@oracle.com, ouyang@cs.pitt.edu, avi.kivity@gmail.com, tglx@linutronix.de, chegu_vinod@hp.com, gregkh@suse.de, linux-kernel@vger.kernel.org, srivatsa.vaddagiri@gmail.com, attilio.rao@citrix.com, pbonzini@redhat.com, torvalds@linux-foundation.org, stephan.diestelhorst@amd.com List-Id: xen-devel@lists.xenproject.org On Wed, Jul 10, 2013 at 12:40:47PM +0200, Peter Zijlstra wrote: > On Wed, Jul 10, 2013 at 01:33:25PM +0300, Gleb Natapov wrote: > > Here's an idea, trim the damn email ;-) -- not only directed at gleb. > Good idea. > > > Ingo, Gleb, > > > > > > From the results perspective, Andrew Theurer, Vinod's test results are > > > pro-pvspinlock. > > > Could you please help me to know what will make it a mergeable > > > candidate?. > > > > > I need to spend more time reviewing it :) The problem with PV interfaces > > is that they are easy to add but hard to get rid of if better solution > > (HW or otherwise) appears. > > How so? Just make sure the registration for the PV interface is optional; that > is, allow it to fail. A guest that fails the PV setup will either have to try > another PV interface or fall back to 'native'. > We have to carry PV around for live migration purposes. PV interface cannot disappear under a running guest. > > > I agree that Jiannan's Preemptable Lock idea is promising and we could > > > evaluate that approach, and make the best one get into kernel and also > > > will carry on discussion with Jiannan to improve that patch. > > That would be great. The work is stalled from what I can tell. > > I absolutely hated that stuff because it wrecked the native code. Yes, the idea was to hide it from native code behind PV hooks. -- Gleb.