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authorPaolo Bonzini <pbonzini@redhat.com>2015-02-06 12:58:42 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2015-04-08 10:46:54 +0200
commit9c8fd1ba2201c072bd3cf6940e2ca4d0a7aed723 (patch)
treecd49f3c0f47344a99e6337da700527ff10ff7a21 /virt/kvm/kvm_main.c
parent362c698f8220e636edf1c40b1935715fa57f492f (diff)
downloadlinux-9c8fd1ba2201c072bd3cf6940e2ca4d0a7aed723.tar.bz2
KVM: x86: optimize delivery of TSC deadline timer interrupt
The newly-added tracepoint shows the following results on the tscdeadline_latency test: qemu-kvm-8387 [002] 6425.558974: kvm_vcpu_wakeup: poll time 10407 ns qemu-kvm-8387 [002] 6425.558984: kvm_vcpu_wakeup: poll time 0 ns qemu-kvm-8387 [002] 6425.561242: kvm_vcpu_wakeup: poll time 10477 ns qemu-kvm-8387 [002] 6425.561251: kvm_vcpu_wakeup: poll time 0 ns and so on. This is because we need to go through kvm_vcpu_block again after the timer IRQ is injected. Avoid it by polling once before entering kvm_vcpu_block. On my machine (Xeon E5 Sandy Bridge) this removes about 500 cycles (7%) from the latency of the TSC deadline timer. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm/kvm_main.c')
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