From patchwork Thu May 19 13:27:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wanpeng Li X-Patchwork-Id: 9127617 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CEDBC60780 for ; Thu, 19 May 2016 13:39:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 61262281FF for ; Thu, 19 May 2016 13:27:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 557572820E; Thu, 19 May 2016 13:27:32 +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=-6.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,FREEMAIL_FROM,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable 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 B47F7281FF for ; Thu, 19 May 2016 13:27:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932369AbcESN1P (ORCPT ); Thu, 19 May 2016 09:27:15 -0400 Received: from mail-pa0-f67.google.com ([209.85.220.67]:34874 "EHLO mail-pa0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932344AbcESN1N (ORCPT ); Thu, 19 May 2016 09:27:13 -0400 Received: by mail-pa0-f67.google.com with SMTP id rw9so7935891pab.2; Thu, 19 May 2016 06:27:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=7eXXSykoR2zjLqlv+u1Jz3CSGa4tL+Pvu/DyjzuA/ko=; b=ScL+Pe8oki1C+rlt3rjZBZa4AYuzeE2KezViFcpzJxvXV1ByOfLlGkXK9ilR0PnT98 +ekRhWui5meKy4Sm53F+Ft3zoRq+iqiR2ocVb09qLNt5sTZqJJbL+G6beiMomWXo3d3H pTBI6dTMYMYK6I7zFSfFw1We5WHOADMZsOyTJoTHHknc0yyDIKxGx/Ab7/kSfsNMcZJe cR5KrCysdaz15BUbSU+Qw7OYeAa1LPEqAb1pA3LVokTCY39L4/KtA4wi0L1L5+TUta93 Ux5ncXCD0usv9OKZWmqz9GD3UixgHPVrdqQCVTkLWj+2PyhMWd1A3IbuYgXvq74QQz5a YstQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=7eXXSykoR2zjLqlv+u1Jz3CSGa4tL+Pvu/DyjzuA/ko=; b=PbS0jHr5un/bXyjnD3MLo/OTQppJs9NxDVmhBhpCnovROnK4Bu1T2CGV29SRr3Jt/f 9TBPJ+ElTcsvUeR15oF9/pbRAfsEqtKBNuG8aK5G71+sGZabeQfcHCIjMydUJrR0Wpkn 5G4GifPJQcKzPUmAsCxsZyC+atw1aXEdpB3FlQokobYWdZj7sNLXvhNDsxtisyr45PMc wlL6JNyugKKzfKaMhaqof2Lw5fQJOhggS0Qh1zGq5yiTB6I2S2LxRTAC2o/wIYGiOtMU GyvtQt1s/L1yXMQ5TCGcs20SOhJSzX8ZNMX4377BQisKPVU9HKRbNaWUbezdsxal8rNe h0Pw== X-Gm-Message-State: AOPr4FWCqvFl7SW5+JyHlf7MBvB8fwNPAKPwI7c6dFyK3wqVns3fvcP4xLk8yrVrzdjvlg== X-Received: by 10.66.119.177 with SMTP id kv17mr19761754pab.57.1463664432845; Thu, 19 May 2016 06:27:12 -0700 (PDT) Received: from kernel.kingsoft.cn ([114.255.44.132]) by smtp.gmail.com with ESMTPSA id c190sm20057180pfb.33.2016.05.19.06.27.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 19 May 2016 06:27:11 -0700 (PDT) From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Wanpeng Li , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , David Matlack , Christian Borntraeger Subject: [PATCH v2] KVM: halt-polling: poll if emulated lapic timer will fire soon Date: Thu, 19 May 2016 21:27:06 +0800 Message-Id: <1463664426-2991-1-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 1.9.1 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 If an emulated lapic timer will fire soon(in the scope of 10us the base of dynamic halt-polling, lower-end of message passing workload latency TCP_RR's poll time < 10us) we can treat it as a short halt, and poll to wait it fire, the fire callback apic_timer_fn() will set KVM_REQ_PENDING_TIMER, and this flag will be check during busy poll. This can avoid context switch overhead and the latency which we wake up vCPU. iperf TCP get ~6% bandwidth improvement. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: David Matlack Cc: Christian Borntraeger Signed-off-by: Wanpeng Li --- v1 -> v2: * add return statement to non-x86 archs * capture never expire case for x86 (hrtimer is not started) arch/arm/include/asm/kvm_host.h | 4 ++++ arch/arm64/include/asm/kvm_host.h | 4 ++++ arch/mips/include/asm/kvm_host.h | 4 ++++ arch/powerpc/include/asm/kvm_host.h | 4 ++++ arch/s390/include/asm/kvm_host.h | 4 ++++ arch/x86/kvm/lapic.c | 11 +++++++++++ arch/x86/kvm/lapic.h | 1 + arch/x86/kvm/x86.c | 5 +++++ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 14 ++++++++++---- 10 files changed, 48 insertions(+), 4 deletions(-) diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 4cd8732..a5fd858 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -284,6 +284,10 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {} static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {} +static inline u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) +{ + return -1ULL; +} static inline void kvm_arm_init_debug(void) {} static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index d49399d..94e227a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -359,6 +359,10 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {} static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {} +static inline u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) +{ + return -1ULL; +} void kvm_arm_init_debug(void); void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index 9a37a10..456bc42 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -813,6 +813,10 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} +static inline u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) +{ + return -1ULL; +} static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {} #endif /* __MIPS_KVM_HOST_H__ */ diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index ec35af3..5986c79 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -729,5 +729,9 @@ static inline void kvm_arch_exit(void) {} static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {} +static inline u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) +{ + return -1ULL; +} #endif /* __POWERPC_KVM_HOST_H__ */ diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 37b9017..bdb01a1 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -696,6 +696,10 @@ static inline void kvm_arch_flush_shadow_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) {} static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} +static inline u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) +{ + return -1ULL; +} void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index bbb5b28..cfeeac3 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -256,6 +256,17 @@ static inline int apic_lvtt_tscdeadline(struct kvm_lapic *apic) return apic->lapic_timer.timer_mode == APIC_LVT_TIMER_TSCDEADLINE; } +u64 apic_get_timer_expire(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + struct hrtimer *timer = &apic->lapic_timer.timer; + + if (!hrtimer_active(timer)) + return -1ULL; + else + return ktime_to_ns(hrtimer_get_remaining(timer)); +} + static inline int apic_lvt_nmi_mode(u32 lvt_val) { return (lvt_val & (APIC_MODE_MASK | APIC_LVT_MASKED)) == APIC_DM_NMI; diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index 891c6da..ee4da6c 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -212,4 +212,5 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, struct kvm_vcpu **dest_vcpu); int kvm_vector_to_index(u32 vector, u32 dest_vcpus, const unsigned long *bitmap, u32 bitmap_size); +u64 apic_get_timer_expire(struct kvm_vcpu *vcpu); #endif diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a8c7ca3..9b5ad99 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7623,6 +7623,11 @@ bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) struct static_key kvm_no_apic_vcpu __read_mostly; EXPORT_SYMBOL_GPL(kvm_no_apic_vcpu); +u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) +{ + return apic_get_timer_expire(vcpu); +} + int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) { struct page *page; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b1fa8f1..14d6c23 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -663,6 +663,7 @@ int kvm_vcpu_yield_to(struct kvm_vcpu *target); void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu); void kvm_load_guest_fpu(struct kvm_vcpu *vcpu); void kvm_put_guest_fpu(struct kvm_vcpu *vcpu); +u64 kvm_arch_timer_remaining(struct kvm_vcpu *vcpu); void kvm_flush_remote_tlbs(struct kvm *kvm); void kvm_reload_remote_mmus(struct kvm *kvm); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index dd4ac9d..e4bb30b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -78,6 +78,9 @@ module_param(halt_poll_ns_grow, uint, S_IRUGO | S_IWUSR); static unsigned int halt_poll_ns_shrink; module_param(halt_poll_ns_shrink, uint, S_IRUGO | S_IWUSR); +/* lower-end of message passing workload latency TCP_RR's poll time < 10us */ +static unsigned int halt_poll_ns_base = 10000; + /* * Ordering of locks: * @@ -1966,7 +1969,7 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu) grow = READ_ONCE(halt_poll_ns_grow); /* 10us base */ if (val == 0 && grow) - val = 10000; + val = halt_poll_ns_base; else val *= grow; @@ -2014,12 +2017,15 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) ktime_t start, cur; DECLARE_SWAITQUEUE(wait); bool waited = false; - u64 block_ns; + u64 block_ns, delta, remaining; + remaining = kvm_arch_timer_remaining(vcpu); start = cur = ktime_get(); - if (vcpu->halt_poll_ns) { - ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns); + if (vcpu->halt_poll_ns || remaining < halt_poll_ns_base) { + ktime_t stop; + delta = vcpu->halt_poll_ns ? vcpu->halt_poll_ns : remaining; + stop = ktime_add_ns(ktime_get(), delta); ++vcpu->stat.halt_attempted_poll; do { /*