KVM: LAPIC: Micro optimize IPI latency
This patch optimizes the virtual IPI emulation sequence:
write ICR2 write ICR2
write ICR read ICR2
read ICR ==> send virtual IPI
read ICR2 write ICR
send virtual IPI
It can reduce kvm-unit-tests/vmexit.flat IPI testing latency(from sender
send IPI to sender receive the ACK) from 3319 cycles to 3203 cycles on
SKylake server.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed