From patchwork Thu Aug 15 04:03:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wanpeng Li X-Patchwork-Id: 11094991 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 19FA51398 for ; Thu, 15 Aug 2019 04:04:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 04F7828814 for ; Thu, 15 Aug 2019 04:04:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E9B0128842; Thu, 15 Aug 2019 04:04:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5B3C128814 for ; Thu, 15 Aug 2019 04:04:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726046AbfHOEDt (ORCPT ); Thu, 15 Aug 2019 00:03:49 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:42649 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725440AbfHOEDt (ORCPT ); Thu, 15 Aug 2019 00:03:49 -0400 Received: by mail-pf1-f194.google.com with SMTP id i30so686079pfk.9; Wed, 14 Aug 2019 21:03:48 -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=4nUx+PiT1A/UTue4lI0LEVNVOUoj29u0rUjKYH9A9qA=; b=q/uCDiqUBuw3t4/EZc02nEuFb8dsKLNA10EeM9XLk1200ynDcNdeWYMbUnyD14zDam pkLvWY6Q71ESRSLEXVZS/1BB7wf2K1WHV+VffFCYB3ABzVCvuEJ/6VOr0QcGTbvng8yI dqBEwtP1VJvxKWATMe78vViTkdlG9YpiKNFAScAddmzB/8vao8LCU0wRoj4/gHjAHlee u1nrEMU+A3qWPSwPeoJaACFMSPpNnSPdlwry9cgpa3xAGhoMznD44XZ+S0A4gAAEbeHn A6R3mK2htyZdjppXXFAZ5p8MlLI02T83EdaFSrcZHGjY1dvMDv33r4WLI4ClXk+CSuPj 1dPQ== 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=4nUx+PiT1A/UTue4lI0LEVNVOUoj29u0rUjKYH9A9qA=; b=A9xgC7mV4X7iNkcZLRGkwYPDANOsw/Tb1toR61A0T8uRcocFuHd81W1r7XsAAZmxOc UvDgFfCnYANKeqSqhK1G1QOhsbZbP1jgTvXvJPz/YWqd+w05JvKnMaw+mRcGUSFqnGoo iJYoSmObrMEakC60SYuNbjWV4qsCWUUcCPro5e2cqZmlxvPGIrfMLUfnfhgSxBdpH5ji f6OEEcmnuIx9/4r65Ci2YsrRzuphwpz2D6ZKMBHx4YI+sWLRb6wWOwK6m46b7dYeoDM/ IXJeXeVZI2M5USMmMPn8nqQ56LA/fkrFPvmVtg4s4DfFRS057Q8r2f7Xm4RUHASoSqIQ G1aQ== X-Gm-Message-State: APjAAAVuoilazZFyn4sSusYkNvxVkBgNU8oCYei5AwHSP+alxdxrn4hH zlZvcF3B31tmgWreRU+pQXP35ktE X-Google-Smtp-Source: APXvYqy835FwkDxLLTJ8VauChuFS3hewWRet1cBkbwe0sDX7yV1440MiWUfblAwVA1LfS7MhfTNKHA== X-Received: by 2002:a17:90a:21eb:: with SMTP id q98mr471321pjc.23.1565841827920; Wed, 14 Aug 2019 21:03:47 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.123]) by smtp.googlemail.com with ESMTPSA id w11sm259423pjr.15.2019.08.14.21.03.46 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 14 Aug 2019 21:03:47 -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?b?UmFkaW0gS3LEjW3DocWZ?= Subject: [PATCH v2] KVM: LAPIC: Periodically revaluate to get conservative lapic_timer_advance_ns Date: Thu, 15 Aug 2019 12:03:37 +0800 Message-Id: <1565841817-25982-1-git-send-email-wanpengli@tencent.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Wanpeng Li Even if for realtime CPUs, cache line bounces, frequency scaling, presence of higher-priority RT tasks, etc can still cause different response. These interferences should be considered and periodically revaluate whether or not the lapic_timer_advance_ns value is the best, do nothing if it is, otherwise recaluate again. Set lapic_timer_advance_ns to the minimal conservative value from all the estimated values. Testing on Skylake server, cat vcpu*/lapic_timer_advance_ns, before patch: 1628 4161 4321 3236 ... Testing on Skylake server, cat vcpu*/lapic_timer_advance_ns, after patch: 1553 1499 1509 1489 ... Testing on Haswell desktop, cat vcpu*/lapic_timer_advance_ns, before patch: 4617 3641 4102 4577 ... Testing on Haswell desktop, cat vcpu*/lapic_timer_advance_ns, after patch: 2775 2892 2764 2775 ... Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li --- arch/x86/kvm/lapic.c | 34 ++++++++++++++++++++++++++++------ arch/x86/kvm/lapic.h | 2 ++ 2 files changed, 30 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index df5cd07..8487d9c 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -69,6 +69,7 @@ #define LAPIC_TIMER_ADVANCE_ADJUST_INIT 1000 /* step-by-step approximation to mitigate fluctuation */ #define LAPIC_TIMER_ADVANCE_ADJUST_STEP 8 +#define LAPIC_TIMER_ADVANCE_RECALC_PERIOD (600 * HZ) static inline int apic_test_vector(int vec, void *bitmap) { @@ -1480,10 +1481,21 @@ static inline void __wait_lapic_expire(struct kvm_vcpu *vcpu, u64 guest_cycles) static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu, s64 advance_expire_delta) { - struct kvm_lapic *apic = vcpu->arch.apic; - u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns; + struct kvm_timer *ktimer = &vcpu->arch.apic->lapic_timer; + u32 timer_advance_ns = ktimer->timer_advance_ns; u64 ns; + /* periodic revaluate */ + if (unlikely(ktimer->timer_advance_adjust_done)) { + ktimer->recalc_timer_advance_ns = jiffies + + LAPIC_TIMER_ADVANCE_RECALC_PERIOD; + if (abs(advance_expire_delta) > LAPIC_TIMER_ADVANCE_ADJUST_DONE) { + timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT; + ktimer->timer_advance_adjust_done = false; + } else + return; + } + /* too early */ if (advance_expire_delta < 0) { ns = -advance_expire_delta * 1000000ULL; @@ -1499,12 +1511,18 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu, } if (abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_DONE) - apic->lapic_timer.timer_advance_adjust_done = true; + ktimer->timer_advance_adjust_done = true; if (unlikely(timer_advance_ns > 5000)) { timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT; - apic->lapic_timer.timer_advance_adjust_done = false; + ktimer->timer_advance_adjust_done = false; + } + ktimer->timer_advance_ns = timer_advance_ns; + + if (ktimer->timer_advance_adjust_done) { + if (ktimer->min_timer_advance_ns > timer_advance_ns) + ktimer->min_timer_advance_ns = timer_advance_ns; + ktimer->timer_advance_ns = ktimer->min_timer_advance_ns; } - apic->lapic_timer.timer_advance_ns = timer_advance_ns; } static void __kvm_wait_lapic_expire(struct kvm_vcpu *vcpu) @@ -1523,7 +1541,8 @@ static void __kvm_wait_lapic_expire(struct kvm_vcpu *vcpu) if (guest_tsc < tsc_deadline) __wait_lapic_expire(vcpu, tsc_deadline - guest_tsc); - if (unlikely(!apic->lapic_timer.timer_advance_adjust_done)) + if (unlikely(!apic->lapic_timer.timer_advance_adjust_done) || + time_before(apic->lapic_timer.recalc_timer_advance_ns, jiffies)) adjust_lapic_timer_advance(vcpu, apic->lapic_timer.advance_expire_delta); } @@ -2301,9 +2320,12 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns) if (timer_advance_ns == -1) { apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT; apic->lapic_timer.timer_advance_adjust_done = false; + apic->lapic_timer.recalc_timer_advance_ns = jiffies; + apic->lapic_timer.min_timer_advance_ns = UINT_MAX; } else { apic->lapic_timer.timer_advance_ns = timer_advance_ns; apic->lapic_timer.timer_advance_adjust_done = true; + apic->lapic_timer.recalc_timer_advance_ns = MAX_JIFFY_OFFSET; } diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index 50053d2..56a05eb 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -31,6 +31,8 @@ struct kvm_timer { u32 timer_mode_mask; u64 tscdeadline; u64 expired_tscdeadline; + unsigned long recalc_timer_advance_ns; + u32 min_timer_advance_ns; u32 timer_advance_ns; s64 advance_expire_delta; atomic_t pending; /* accumulated triggered timers */