From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757154Ab3EVT4U (ORCPT ); Wed, 22 May 2013 15:56:20 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:40011 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757105Ab3EVT4R (ORCPT ); Wed, 22 May 2013 15:56:17 -0400 From: Xiao Guangrong To: gleb@redhat.com Cc: avi.kivity@gmail.com, mtosatti@redhat.com, pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Xiao Guangrong Subject: [PATCH v7 04/11] KVM: MMU: zap pages in batch Date: Thu, 23 May 2013 03:55:53 +0800 Message-Id: <1369252560-11611-5-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <1369252560-11611-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> References: <1369252560-11611-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13052219-2674-0000-0000-0000091330B5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Zap at lease 10 pages before releasing mmu-lock to reduce the overload caused by requiring lock After the patch, kvm_zap_obsolete_pages can forward progress anyway, so update the comments [ It improves kernel building 0.6% ~ 1% ] Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 35 +++++++++++------------------------ 1 files changed, 11 insertions(+), 24 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index f302540..688e755 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4203,14 +4203,18 @@ restart: spin_unlock(&kvm->mmu_lock); } +#define BATCH_ZAP_PAGES 10 static void kvm_zap_obsolete_pages(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; LIST_HEAD(invalid_list); + int batch = 0; restart: list_for_each_entry_safe_reverse(sp, node, &kvm->arch.active_mmu_pages, link) { + int ret; + /* * No obsolete page exists before new created page since * active_mmu_pages is the FIFO list. @@ -4219,28 +4223,6 @@ restart: break; /* - * Do not repeatedly zap a root page to avoid unnecessary - * KVM_REQ_MMU_RELOAD, otherwise we may not be able to - * progress: - * vcpu 0 vcpu 1 - * call vcpu_enter_guest(): - * 1): handle KVM_REQ_MMU_RELOAD - * and require mmu-lock to - * load mmu - * repeat: - * 1): zap root page and - * send KVM_REQ_MMU_RELOAD - * - * 2): if (cond_resched_lock(mmu-lock)) - * - * 2): hold mmu-lock and load mmu - * - * 3): see KVM_REQ_MMU_RELOAD bit - * on vcpu->requests is set - * then return 1 to call - * vcpu_enter_guest() again. - * goto repeat; - * * Since we are reversely walking the list and the invalid * list will be moved to the head, skip the invalid page * can help us to avoid the infinity list walking. @@ -4248,13 +4230,18 @@ restart: if (sp->role.invalid) continue; - if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { + if (batch >= BATCH_ZAP_PAGES && + (need_resched() || spin_needbreak(&kvm->mmu_lock))) { + batch = 0; kvm_mmu_commit_zap_page(kvm, &invalid_list); cond_resched_lock(&kvm->mmu_lock); goto restart; } - if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list)) + ret = kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + batch += ret; + + if (ret) goto restart; } -- 1.7.7.6