Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965603AbbGVQdo (ORCPT ); Wed, 22 Jul 2015 12:33:44 -0400 Received: from relay.parallels.com ([195.214.232.42]:51442 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965204AbbGVQdk (ORCPT ); Wed, 22 Jul 2015 12:33:40 -0400 Date: Wed, 22 Jul 2015 19:33:17 +0300 From: Vladimir Davydov To: Andrew Morton CC: Andres Lagar-Cavilla , Minchan Kim , Raghavendra K T , Johannes Weiner , Michal Hocko , "Greg Thelen" , Michel Lespinasse , "David Rientjes" , Pavel Emelyanov , Cyrill Gorcunov , Jonathan Corbet , , , , , Subject: Re: [PATCH -mm v9 5/8] mmu-notifier: add clear_young callback Message-ID: <20150722163317.GO23374@esperanza> References: <20150721085108.GA18673@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20150721085108.GA18673@esperanza> X-Originating-IP: [10.30.4.177] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2530 Lines: 58 Hi Andrew, Would you mind merging this incremental patch to the original one? Or should I better resubmit the whole series with all the fixes? On Tue, Jul 21, 2015 at 11:51:08AM +0300, Vladimir Davydov wrote: > On Mon, Jul 20, 2015 at 11:34:21AM -0700, Andres Lagar-Cavilla wrote: > > On Sun, Jul 19, 2015 at 5:31 AM, Vladimir Davydov > [...] > > > +static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn, > > > + struct mm_struct *mm, > > > + unsigned long start, > > > + unsigned long end) > > > +{ > > > + struct kvm *kvm = mmu_notifier_to_kvm(mn); > > > + int young, idx; > > > + > > > > > If you need to cut out another version please add comments as to the two > > issues raised: > > - This doesn't proactively flush TLBs -- not obvious if it should. > > - This adversely affects performance in Pre_haswell Intel EPT. > > Oops, I stopped reading your e-mail in reply to the previous version of > this patch as soon as I saw the Reviewed-by tag, so I missed your > request for the comment, sorry about that. > > Here it goes (incremental): > --- > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index ff4173ce6924..e69a5cb99571 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -397,6 +397,19 @@ static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn, > > idx = srcu_read_lock(&kvm->srcu); > spin_lock(&kvm->mmu_lock); > + /* > + * Even though we do not flush TLB, this will still adversely > + * affect performance on pre-Haswell Intel EPT, where there is > + * no EPT Access Bit to clear so that we have to tear down EPT > + * tables instead. If we find this unacceptable, we can always > + * add a parameter to kvm_age_hva so that it effectively doesn't > + * do anything on clear_young. > + * > + * Also note that currently we never issue secondary TLB flushes > + * from clear_young, leaving this job up to the regular system > + * cadence. If we find this inaccurate, we might come up with a > + * more sophisticated heuristic later. > + */ > young = kvm_age_hva(kvm, start, end); > spin_unlock(&kvm->mmu_lock); > srcu_read_unlock(&kvm->srcu, idx); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/