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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 EF7D0C433EF for ; Mon, 9 Sep 2019 01:40:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C62EE216C8 for ; Mon, 9 Sep 2019 01:40:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="VV7Wrq6M" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732446AbfIIBkf (ORCPT ); Sun, 8 Sep 2019 21:40:35 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:45025 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731948AbfIIBkf (ORCPT ); Sun, 8 Sep 2019 21:40:35 -0400 Received: by mail-pl1-f196.google.com with SMTP id k1so5798201pls.11; Sun, 08 Sep 2019 18:40:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=k1Kf8xMbkRDHr8n0Ak2LvAQxnQ9bC0rCE/1ZgT65+C4=; b=VV7Wrq6MY+yzFcwIwG1efanp6VJ8HOZ3HH9TT5BHjXp0/4DuBcVOdgszMBySBSDaU4 aW29GAKuwuAweCAxIL4mBethP+Dp9f8+uky/+fop7aBAzRAd/l+trbYZDHUXwuEY4vgt Jc2b4Mkej7a3+I+3ngg2BukVELBFUvfQpGQ/1+OZTgyK1VoR2Z6q9SfwZ52ZhNgRSjYk fNAhI1QXHeDCa468pwoXpLJhLD6DJirSv2wvwzlmIxD5mwQXOE0unyQkGU0HDAdk1VWR FJxyQMpEzUoAr8EqAIoEyT/2kwwbziG0dd1rcMHoZgxvOS3d2TbQXjzQM3idAt+SRUYQ lQsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=k1Kf8xMbkRDHr8n0Ak2LvAQxnQ9bC0rCE/1ZgT65+C4=; b=oTVdum2OpyBcO5c/7q1MrYJ1Q8khoZIVpzuMeH6+F2xPNxhWGTXen9BrKilAhNHjzp H3SBpkoeTgyrxVMUDCm16c5TUJUHlqFSe/glMy2OQVqGE6INUeH//6eD7KpxD9KKBRZI wCuPrlykMkWK/Wwq9SW7ngKEa9bVA4R54CfNea+0zXTycaqFLyaYzVayDeIHTPp1InNZ 9TJyhWYx1tK1CbaiA9fX7JshO3kYAREsGXmJxBfTbq9WFHReQHb4WaOpPme4AD6DNlb6 KoabJ52u0IJcnj7p77cd5hlzSN5VpsYpxh3p92ZkLKB5i99ewpBL34E9GpNAbDQz68aL VGTQ== X-Gm-Message-State: APjAAAVPvwoNByNg59ckbPNuLxCJfdfdqhzkSMfeTjipXC1Ju92aIkW2 Nx4636XFXt6tew/f1QP1P/Jbljy3 X-Google-Smtp-Source: APXvYqx/KsEp8b0srchrNLkvc8bnJcJN2/lMsKwOLdoaFG+Diy+DWrPllHpcniCsDmSRUXTwZZilrQ== X-Received: by 2002:a17:902:7c88:: with SMTP id y8mr21451213pll.306.1567993234474; Sun, 08 Sep 2019 18:40:34 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.123]) by smtp.googlemail.com with ESMTPSA id j26sm12413196pfe.181.2019.09.08.18.40.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 08 Sep 2019 18:40:33 -0700 (PDT) From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Waiman Long , loobinliu@tencent.com, stable@vger.kernel.org Subject: [PATCH] Revert "locking/pvqspinlock: Don't wait if vCPU is preempted" Date: Mon, 9 Sep 2019 09:40:28 +0800 Message-Id: <1567993228-23668-1-git-send-email-wanpengli@tencent.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li This patch reverts commit 75437bb304b20 (locking/pvqspinlock: Don't wait if vCPU is preempted), we found great regression caused by this commit. Xeon Skylake box, 2 sockets, 40 cores, 80 threads, three VMs, each is 80 vCPUs. The score of ebizzy -M can reduce from 13000-14000 records/s to 1700-1800 records/s with this commit. Host Guest score vanilla + w/o kvm optimizes vanilla 1700-1800 records/s vanilla + w/o kvm optimizes vanilla + revert 13000-14000 records/s vanilla + w/ kvm optimizes vanilla 4500-5000 records/s vanilla + w/ kvm optimizes vanilla + revert 14000-15500 records/s Exit from aggressive wait-early mechanism can result in yield premature and incur extra scheduling latency in over-subscribe scenario. kvm optimizes: [1] commit d73eb57b80b (KVM: Boost vCPUs that are delivering interrupts) [2] commit 266e85a5ec9 (KVM: X86: Boost queue head vCPU to mitigate lock waiter preemption) Tested-by: loobinliu@tencent.com Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Waiman Long Cc: Paolo Bonzini Cc: Radim Krčmář Cc: loobinliu@tencent.com Cc: stable@vger.kernel.org Fixes: 75437bb304b20 (locking/pvqspinlock: Don't wait if vCPU is preempted) Signed-off-by: Wanpeng Li --- kernel/locking/qspinlock_paravirt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 89bab07..e84d21a 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -269,7 +269,7 @@ pv_wait_early(struct pv_node *prev, int loop) if ((loop & PV_PREV_CHECK_MASK) != 0) return false; - return READ_ONCE(prev->state) != vcpu_running || vcpu_is_preempted(prev->cpu); + return READ_ONCE(prev->state) != vcpu_running; } /* -- 2.7.4