From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH v5 8/8] KVM: MMU: zap pages in batch Date: Thu, 16 May 2013 21:31:24 +0800 Message-ID: <5194DFAC.8010707@linux.vnet.ibm.com> References: <1368706673-8530-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <1368706673-8530-9-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <5194D507.5080005@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: gleb@redhat.com, avi.kivity@gmail.com, mtosatti@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org To: Paolo Bonzini Return-path: Received: from e23smtp09.au.ibm.com ([202.81.31.142]:41069 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754064Ab3EPNbb (ORCPT ); Thu, 16 May 2013 09:31:31 -0400 Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 17 May 2013 10:29:03 +1000 In-Reply-To: <5194D507.5080005@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/16/2013 08:45 PM, Paolo Bonzini wrote: > Il 16/05/2013 14:17, Xiao Guangrong ha scritto: >> Zap at lease 10 pages before releasing mmu-lock to reduce the overload >> caused by requiring lock >> >> [ It improves kernel building 0.6% ~ 1% ] >> >> Signed-off-by: Xiao Guangrong >> --- >> arch/x86/kvm/mmu.c | 11 ++++++++--- >> 1 files changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index e12f431..9c27fda 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -4216,10 +4216,12 @@ restart: >> spin_unlock(&kvm->mmu_lock); >> } >> >> +#define BATCH_ZAP_PAGES 10 >> static void zap_invalid_pages(struct kvm *kvm) >> { >> struct kvm_mmu_page *sp, *node; >> LIST_HEAD(invalid_list); >> + int batch = 0; >> >> restart: >> list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { >> @@ -4256,11 +4258,14 @@ restart: >> * Need not flush tlb since we only zap the sp with invalid >> * generation number. >> */ >> - if (cond_resched_lock(&kvm->mmu_lock)) >> + if ((batch >= BATCH_ZAP_PAGES) && >> + cond_resched_lock(&kvm->mmu_lock)) { >> + batch = 0; >> goto restart; >> + } >> >> - if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list)) >> - goto restart; >> + batch += kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); >> + goto restart; > > Would this look again and again at the same page if > kvm_mmu_prepare_zap_page returns 0? We skip the invalid page (sp->role.invalid) before call kvm_mmu_prepare_zap_page so that kvm_mmu_prepare_zap_page can not meet the same page. ;)