KVM: X86: Improve latency for single target IPI fastpath

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IPI and Timer cause the main MSRs write vmexits in cloud environment
observation, let's optimize virtual IPI latency more aggressively to
inject target IPI as soon as possible.

Running kvm-unit-tests/vmexit.flat IPI testing on SKX server, disable
adaptive advance lapic timer and adaptive halt-polling to avoid the
interference, this patch can give another 7% improvement.

w/o fastpath   -> x86.c fastpath      4238 -> 3543  16.4%
x86.c fastpath -> vmx.c fastpath      3543 -> 3293     7%
w/o fastpath   -> vmx.c fastpath      4238 -> 3293  22.3%

Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200410174703.1138-3-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Wanpeng Li 2020-04-10 10:47:03 -07:00 • committed by Paolo Bonzini

parent 873e1da169

commit a9ab13ff6e

4 changed files with 34 additions and 23 deletions

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5

arch/x86/include/asm/kvm_host.h

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24

arch/x86/kvm/svm/svm.c

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22

arch/x86/kvm/vmx/vmx.c

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6

arch/x86/kvm/x86.c

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