KVM: LAPIC: Narrow the timer latency between wait_lapic_expire and world switch

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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>
Message-Id: <1621339235-11131-5-git-send-email-wanpengli@tencent.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Wanpeng Li 2021-05-18 05:00:35 -07:00 • committed by Paolo Bonzini

parent fb0f94794b

commit 9805cf03fd

1 changed files with 11 additions and 3 deletions

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arch/x86/kvm/lapic.c

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