From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: [patch 2/4] KVM: MMU: collapse remote TLB flushes on root sync Date: Mon, 01 Dec 2008 22:32:03 -0200 Message-ID: <20081202003333.674155915@localhost.localdomain> References: <20081202003201.739616208@localhost.localdomain> Cc: kvm@vger.kernel.org, Marcelo Tosatti To: Avi Kivity Return-path: Received: from mx2.redhat.com ([66.187.237.31]:53759 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752782AbYLBAkP (ORCPT ); Mon, 1 Dec 2008 19:40:15 -0500 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id mB20eFH4002734 for ; Mon, 1 Dec 2008 19:40:15 -0500 Content-Disposition: inline; filename=kvm-collapse-tlb-flush Sender: kvm-owner@vger.kernel.org List-ID: Collapse remote TLB flushes on root sync. kernbench is 2.7% faster on 4-way guest. Improvements have been seen with other loads such as AIM7. Signed-off-by: Marcelo Tosatti Index: kvm/arch/x86/kvm/mmu.c =================================================================== --- kvm.orig/arch/x86/kvm/mmu.c +++ kvm/arch/x86/kvm/mmu.c @@ -621,7 +621,7 @@ static u64 *rmap_next(struct kvm *kvm, u return NULL; } -static void rmap_write_protect(struct kvm *kvm, u64 gfn) +static int rmap_write_protect(struct kvm *kvm, u64 gfn) { unsigned long *rmapp; u64 *spte; @@ -667,8 +667,7 @@ static void rmap_write_protect(struct kv spte = rmap_next(kvm, rmapp, spte); } - if (write_protected) - kvm_flush_remote_tlbs(kvm); + return write_protected; } static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp) @@ -1083,7 +1082,8 @@ static int kvm_sync_page(struct kvm_vcpu return 1; } - rmap_write_protect(vcpu->kvm, sp->gfn); + if (rmap_write_protect(vcpu->kvm, sp->gfn)) + kvm_flush_remote_tlbs(vcpu->kvm); kvm_unlink_unsync_page(vcpu->kvm, sp); if (vcpu->arch.mmu.sync_page(vcpu, sp)) { kvm_mmu_zap_page(vcpu->kvm, sp); @@ -1162,6 +1162,14 @@ static void mmu_sync_children(struct kvm kvm_mmu_pages_init(parent, &parents, &pages); while (mmu_unsync_walk(parent, &pages)) { + int protected = 0; + + for_each_sp(pages, sp, parents, i) + protected |= rmap_write_protect(vcpu->kvm, sp->gfn); + + if (protected) + kvm_flush_remote_tlbs(vcpu->kvm); + for_each_sp(pages, sp, parents, i) { kvm_sync_page(vcpu, sp); mmu_pages_clear_parents(&parents); @@ -1226,7 +1234,8 @@ static struct kvm_mmu_page *kvm_mmu_get_ sp->role = role; hlist_add_head(&sp->hash_link, bucket); if (!metaphysical) { - rmap_write_protect(vcpu->kvm, gfn); + if (rmap_write_protect(vcpu->kvm, gfn)) + kvm_flush_remote_tlbs(vcpu->kvm); account_shadowed(vcpu->kvm, gfn); } if (shadow_trap_nonpresent_pte != shadow_notrap_nonpresent_pte) --