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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2016-05-17 10:49:22 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-05-18 18:04:22 +0200 |
| commit | 2086d3200dc9966c96a6c319a1214a94f00223f8 (patch) | |
| tree | d894bf017417f0349d8fda96c86dc414aec875e2 | |
| parent | c4a8de357ef1916c38e4419c0bafad86ca4fbcf7 (diff) | |
| download | linux-2086d3200dc9966c96a6c319a1214a94f00223f8.tar.bz2 | |
KVM: shrink halt polling even more for invalid wakeups
commit 3491caf2755e ("KVM: halt_polling: provide a way to qualify
wakeups during poll") added more aggressive shrinking of the
polling interval if the wakeup did not match some criteria. This
still allows to keep polling enabled if the polling time was
smaller that the current max poll time (block_ns <= vcpu->halt_poll_ns).
Performance measurement shows that even more aggressive shrinking
(shrink polling on any invalid wakeup) reduces absolute and relative
(to the workload) CPU usage even further.
Cc: David Matlack <dmatlack@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | virt/kvm/kvm_main.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 21f6498d52e3..7e22998a1ceb 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2055,12 +2055,13 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) out: block_ns = ktime_to_ns(cur) - ktime_to_ns(start); - if (halt_poll_ns) { + if (!vcpu_valid_wakeup(vcpu)) + shrink_halt_poll_ns(vcpu); + else if (halt_poll_ns) { if (block_ns <= vcpu->halt_poll_ns) ; /* we had a long block, shrink polling */ - else if (!vcpu_valid_wakeup(vcpu) || - (vcpu->halt_poll_ns && block_ns > halt_poll_ns)) + else if (vcpu->halt_poll_ns && block_ns > halt_poll_ns) shrink_halt_poll_ns(vcpu); /* we had a short halt and our poll time is too small */ else if (vcpu->halt_poll_ns < halt_poll_ns && |