From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752315Ab2GEEPz (ORCPT ); Thu, 5 Jul 2012 00:15:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48873 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751418Ab2GEEPB (ORCPT ); Thu, 5 Jul 2012 00:15:01 -0400 Date: Wed, 4 Jul 2012 23:37:46 -0300 From: Marcelo Tosatti To: Nikunj A Dadhania Cc: peterz@infradead.org, mingo@elte.hu, avi@redhat.com, raghukt@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, jeremy@goop.org, vatsa@linux.vnet.ibm.com, hpa@zytor.com Subject: Re: [PATCH v2 5/7] KVM: Introduce PV kick in flush tlb Message-ID: <20120705023746.GC3652@amt.cnet> References: <20120604050223.4560.2874.stgit@abhimanyu.in.ibm.com> <20120604050755.4560.24727.stgit@abhimanyu.in.ibm.com> <20120703080713.GA12579@amt.cnet> <87r4stckv5.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87r4stckv5.fsf@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 03, 2012 at 01:55:02PM +0530, Nikunj A Dadhania wrote: > On Tue, 3 Jul 2012 05:07:13 -0300, Marcelo Tosatti wrote: > > On Mon, Jun 04, 2012 at 10:38:17AM +0530, Nikunj A. Dadhania wrote: > > > In place of looping continuously introduce a halt if we do not succeed > > > after some time. > > > > > > For vcpus that were running an IPI is sent. In case, it went to sleep > > > between this, we will be doing flush_on_enter(harmless). But as a > > > flush IPI was already sent, that will be processed in ipi handler, > > > this might result into something undesireable, i.e. It might clear the > > > flush_mask of a new request. > > > > > > So after sending an IPI and waiting for a while, do a halt and wait > > > for a kick from the last vcpu. > > > > > > Signed-off-by: Srivatsa Vaddagiri > > > Signed-off-by: Nikunj A. Dadhania > > > > Again, was it determined that this is necessary from data of > > benchmarking on the in-guest-mode/out-guest-mode patch? > > > No, this is more of a fix wrt algo. Please have numbers for the improvement relative to the previous patch. It introduces a dependency, these (pvtlbflush and pvspinlocks) are separate features. It is useful to switch them on/off individually.