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=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 943C1C433DF for ; Tue, 23 Jun 2020 19:35:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 760032098B for ; Tue, 23 Jun 2020 19:35:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387546AbgFWTfu (ORCPT ); Tue, 23 Jun 2020 15:35:50 -0400 Received: from mga11.intel.com ([192.55.52.93]:11007 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733309AbgFWTfp (ORCPT ); Tue, 23 Jun 2020 15:35:45 -0400 IronPort-SDR: H10Jgg2UxxfeaY7xUaV/Mt4DpUyYVYice8NxIgp1SwXQRN2xZr7gPxhvWqnEGhZ5BYZBSCvGnI VLxyoFUAusfg== X-IronPort-AV: E=McAfee;i="6000,8403,9661"; a="142430976" X-IronPort-AV: E=Sophos;i="5.75,272,1589266800"; d="scan'208";a="142430976" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2020 12:35:44 -0700 IronPort-SDR: KzHXMSfU2DHmk3eYK1ZX/Merfa9fzMuYT/5+BSbiITlLZIHTdodU9dUWHih0nr0PmCsIhgUX30 9j6C8skSuTmw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,272,1589266800"; d="scan'208";a="263428296" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.152]) by fmsmga007.fm.intel.com with ESMTP; 23 Jun 2020 12:35:44 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/4] KVM: x86/mmu: Batch zap MMU pages when shrinking the slab Date: Tue, 23 Jun 2020 12:35:41 -0700 Message-Id: <20200623193542.7554-4-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200623193542.7554-1-sean.j.christopherson@intel.com> References: <20200623193542.7554-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use the recently introduced kvm_mmu_zap_oldest_mmu_pages() to batch zap MMU pages when shrinking a slab. This fixes a long standing issue where KVM's shrinker implementation is completely ineffective due to zapping only a single page. E.g. without batch zapping, forcing a scan via drop_caches basically has no impact on a VM with ~2k shadow pages. With batch zapping, the number of shadow pages can be reduced to a few hundred pages in one or two runs of drop_caches. Note, if the default batch size (currently 128) is problematic, e.g. zapping 128 pages holds mmu_lock for too long, KVM can bound the batch size by setting @batch in mmu_shrinker. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 8c85a3a178f4..4d40b21a67bd 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2825,19 +2825,6 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, } } -static bool prepare_zap_oldest_mmu_page(struct kvm *kvm, - struct list_head *invalid_list) -{ - struct kvm_mmu_page *sp; - - if (list_empty(&kvm->arch.active_mmu_pages)) - return false; - - sp = list_last_entry(&kvm->arch.active_mmu_pages, - struct kvm_mmu_page, link); - return kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); -} - static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, unsigned long nr_to_zap) { @@ -6125,9 +6112,7 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) goto unlock; } - if (prepare_zap_oldest_mmu_page(kvm, &invalid_list)) - freed++; - kvm_mmu_commit_zap_page(kvm, &invalid_list); + freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan); unlock: spin_unlock(&kvm->mmu_lock); -- 2.26.0