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| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-02-06 12:58:42 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-04-08 10:46:54 +0200 |
| commit | 9c8fd1ba2201c072bd3cf6940e2ca4d0a7aed723 (patch) | |
| tree | cd49f3c0f47344a99e6337da700527ff10ff7a21 /virt/kvm | |
| parent | 362c698f8220e636edf1c40b1935715fa57f492f (diff) | |
| download | op-kernel-dev-9c8fd1ba2201c072bd3cf6940e2ca4d0a7aed723.zip op-kernel-dev-9c8fd1ba2201c072bd3cf6940e2ca4d0a7aed723.tar.gz | |
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')
0 files changed, 0 insertions, 0 deletions
