From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3FDDC34026 for ; Tue, 18 Feb 2020 11:00:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1772206E2 for ; Tue, 18 Feb 2020 11:00:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726496AbgBRLAb (ORCPT ); Tue, 18 Feb 2020 06:00:31 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:10637 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726403AbgBRLAa (ORCPT ); Tue, 18 Feb 2020 06:00:30 -0500 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id B6052C161B520BB25B62; Tue, 18 Feb 2020 19:00:23 +0800 (CST) Received: from localhost (10.133.205.84) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.439.0; Tue, 18 Feb 2020 19:00:17 +0800 From: Jay Zhou To: CC: , , , , , Subject: [PATCH] KVM: x86: enable dirty log gradually in small chunks Date: Tue, 18 Feb 2020 19:00:13 +0800 Message-ID: <20200218110013.15640-1-jianjay.zhou@huawei.com> X-Mailer: git-send-email 2.14.1.windows.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.133.205.84] X-CFilter-Loop: Reflected Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org It could take kvm->mmu_lock for an extended period of time when enabling dirty log for the first time. The main cost is to clear all the D-bits of last level SPTEs. This situation can benefit from manual dirty log protect as well, which can reduce the mmu_lock time taken. The sequence is like this: 1. Set all the bits of the first dirty bitmap to 1 when enabling dirty log for the first time 2. Only write protect the huge pages 3. KVM_GET_DIRTY_LOG returns the dirty bitmap info 4. KVM_CLEAR_DIRTY_LOG will clear D-bit for each of the leaf level SPTEs gradually in small chunks Under the Intel(R) Xeon(R) Gold 6152 CPU @ 2.10GHz environment, I did some tests with a 128G windows VM and counted the time taken of memory_global_dirty_log_start, here is the numbers: VM Size Before After optimization 128G 460ms 10ms Signed-off-by: Jay Zhou --- arch/x86/kvm/vmx/vmx.c | 5 +++++ include/linux/kvm_host.h | 5 +++++ virt/kvm/kvm_main.c | 10 ++++++++-- 3 files changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 3be25ec..a8d64f6 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7201,7 +7201,12 @@ static void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu) static void vmx_slot_enable_log_dirty(struct kvm *kvm, struct kvm_memory_slot *slot) { +#if CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT + if (!kvm->manual_dirty_log_protect) + kvm_mmu_slot_leaf_clear_dirty(kvm, slot); +#else kvm_mmu_slot_leaf_clear_dirty(kvm, slot); +#endif kvm_mmu_slot_largepage_remove_write_access(kvm, slot); } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e89eb67..fd149b0 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -360,6 +360,11 @@ static inline unsigned long *kvm_second_dirty_bitmap(struct kvm_memory_slot *mem return memslot->dirty_bitmap + len / sizeof(*memslot->dirty_bitmap); } +static inline void kvm_set_first_dirty_bitmap(struct kvm_memory_slot *memslot) +{ + bitmap_set(memslot->dirty_bitmap, 0, memslot->npages); +} + struct kvm_s390_adapter_int { u64 ind_addr; u64 summary_addr; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 70f03ce..08565ed 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -862,7 +862,8 @@ static int kvm_vm_release(struct inode *inode, struct file *filp) * Allocation size is twice as large as the actual dirty bitmap size. * See x86's kvm_vm_ioctl_get_dirty_log() why this is needed. */ -static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot) +static int kvm_create_dirty_bitmap(struct kvm *kvm, + struct kvm_memory_slot *memslot) { unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot); @@ -870,6 +871,11 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot) if (!memslot->dirty_bitmap) return -ENOMEM; +#if CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT + if (kvm->manual_dirty_log_protect) + kvm_set_first_dirty_bitmap(memslot); +#endif + return 0; } @@ -1094,7 +1100,7 @@ int __kvm_set_memory_region(struct kvm *kvm, /* Allocate page dirty bitmap if needed */ if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) { - if (kvm_create_dirty_bitmap(&new) < 0) + if (kvm_create_dirty_bitmap(kvm, &new) < 0) goto out_free; } -- 1.8.3.1