From: Sean Christopherson <seanjc@google.com>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v4 5/5] KVM: LAPIC: Narrow the timer latency between wait_lapic_expire and world switch
Date: Tue, 18 May 2021 19:13:58 +0000 [thread overview]
Message-ID: <YKQR9rq9WNT6dauh@google.com> (raw)
In-Reply-To: <1621339235-11131-5-git-send-email-wanpengli@tencent.com>
On Tue, May 18, 2021, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Let's treat lapic_timer_advance_ns automatic tuning logic as hypervisor
> overhead, move it before wait_lapic_expire instead of between wait_lapic_expire
> and the world switch, the wait duration should be calculated by the
> up-to-date guest_tsc after the overhead of automatic tuning logic. This
> patch reduces ~30+ cycles for kvm-unit-tests/tscdeadline-latency when testing
> busy waits.
>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
Reviewed-by: Sean Christopherson <seanjc@google.com>
next prev parent reply other threads:[~2021-05-18 19:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 12:00 [PATCH v4 1/5] KVM: exit halt polling on need_resched() for both book3s and generic halt-polling Wanpeng Li
2021-05-18 12:00 ` [PATCH v4 2/5] KVM: X86: Bail out of direct yield in case of under-committed scenarios Wanpeng Li
2021-05-18 19:21 ` Sean Christopherson
2021-05-19 2:57 ` Wanpeng Li
2021-05-24 13:42 ` Paolo Bonzini
2021-05-24 13:47 ` Wanpeng Li
2021-05-18 12:00 ` [PATCH v4 3/5] KVM: X86: Fix vCPU preempted state from guest's point of view Wanpeng Li
2021-05-18 12:00 ` [PATCH v4 4/5] KVM: X86: hyper-v: Task srcu lock when accessing kvm_memslots() Wanpeng Li
2021-05-18 12:00 ` [PATCH v4 5/5] KVM: LAPIC: Narrow the timer latency between wait_lapic_expire and world switch Wanpeng Li
2021-05-18 19:13 ` Sean Christopherson [this message]
2021-05-24 13:46 ` [PATCH v4 1/5] KVM: exit halt polling on need_resched() for both book3s and generic halt-polling Paolo Bonzini
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