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=-9.7 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=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 B70C8C3A5A1 for ; Wed, 28 Aug 2019 08:19:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8AA8D2189D for ; Wed, 28 Aug 2019 08:19:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pWudp200" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726444AbfH1ITI (ORCPT ); Wed, 28 Aug 2019 04:19:08 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:35107 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726292AbfH1ITI (ORCPT ); Wed, 28 Aug 2019 04:19:08 -0400 Received: by mail-pf1-f196.google.com with SMTP id d85so1228853pfd.2; Wed, 28 Aug 2019 01:19:08 -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=W7GKLPAGmCBm9bFk16i6qv/H1D4Ue6Mzr647i7CBlq8=; b=pWudp200xJPqLG8gbdZmOS6rC3AjwavyXDrm65Uh0QOIEuGy8SI1wF1eEfhT+GssFA nRJVI5i83WwNJ4r56NkhqF/Ieny0DrariGtiaT+yYu2zm5Q7zl6PShX4L0mzHpkIM9XT fQokuycnWDeZRJTLORLRPCPp/Ln/71vBoraawn3RVZfbZP+mUp3VIU9QYBL3MQVlBmSY mdAlt64YdiycL8cJYGsmzF7S3K662B9wgJrf/m8+xaMgNcPnT4y2I10XksQ6o+CyVBcq GwZBeZFZ2zm7+jraFi5t4XXTyrhgSB+iAMu9b4b0pO214BzYh1h0z9zrQEbM29h6GHwT qDeA== 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=W7GKLPAGmCBm9bFk16i6qv/H1D4Ue6Mzr647i7CBlq8=; b=PM0cGRcON27/5MK7z+iMxN6b8V1VMi+L/tfmi68OmgkDS0YYs3n7+kj7/gOwJayNoh oAZagQU4LKSBvQSsfNZH2catZ/rEvicmSVvjFbL1xKLaEhoNkTOzqxNKgIiUtKeME4UF qjNYmKffcn8cyrkfbkSFCArEPg8FXJ5bsJoudBuWet1UbIV/NNuedojGIKpXlqAqJNJD MHmTDL+yw3rdQ6bCAfuJQpvw4T4kdJPFo3cUuI30skIx2S84J5dnuchSyC33wabbOuLX MtmtpIfCgzssYkYvUUWaxYlvAU8xVj2N1M0ctLcUqSzC0oHyfNmhR/YEr/Drhq9WvTrI yd8g== X-Gm-Message-State: APjAAAUKxIxjJpNesuj+W5ybm3z7ajkOYNZl/rVUppGrX980kWStIHGV 9wP7K79WyVrfaIQORSw+hRSbhmSI X-Google-Smtp-Source: APXvYqxHwaHzAOj0x1bmSnv3GB4eFOeCcWwCxN0e7YwF2BcgKx54IpxvhYZ9fB+7k8TSxktmU2sy8g== X-Received: by 2002:a63:3148:: with SMTP id x69mr2244026pgx.300.1566980347471; Wed, 28 Aug 2019 01:19:07 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.123]) by smtp.googlemail.com with ESMTPSA id g1sm1787263pgg.27.2019.08.28.01.19.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 28 Aug 2019 01:19:07 -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?= Subject: [PATCH v3 1/2] KVM: LAPIC: Tune lapic_timer_advance_ns smoothly Date: Wed, 28 Aug 2019 16:19:01 +0800 Message-Id: <1566980342-22045-1-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 Using a moving average based on per-vCPU lapic_timer_advance_ns to tune smoothly, filter out drastic fluctuation which prevents this before, let's assume it is 10000 cycles. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li --- arch/x86/kvm/lapic.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index e904ff0..181537a 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_FILTER 10000 static inline int apic_test_vector(int vec, void *bitmap) { @@ -1484,23 +1485,28 @@ 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; - u64 ns; + u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns, ns; + + if (abs(advance_expire_delta) > LAPIC_TIMER_ADVANCE_FILTER) + /* filter out drastic fluctuations */ + return; /* too early */ if (advance_expire_delta < 0) { ns = -advance_expire_delta * 1000000ULL; do_div(ns, vcpu->arch.virtual_tsc_khz); - timer_advance_ns -= min((u32)ns, - timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP); + timer_advance_ns -= ns; } else { /* too late */ ns = advance_expire_delta * 1000000ULL; do_div(ns, vcpu->arch.virtual_tsc_khz); - timer_advance_ns += min((u32)ns, - timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP); + timer_advance_ns += ns; } + timer_advance_ns = (apic->lapic_timer.timer_advance_ns * + (LAPIC_TIMER_ADVANCE_ADJUST_STEP - 1) + advance_expire_delta) / + LAPIC_TIMER_ADVANCE_ADJUST_STEP; + if (abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_DONE) apic->lapic_timer.timer_advance_adjust_done = true; if (unlikely(timer_advance_ns > 5000)) { -- 2.7.4