From 2086d3200dc9966c96a6c319a1214a94f00223f8 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Tue, 17 May 2016 10:49:22 +0200 Subject: [PATCH] KVM: shrink halt polling even more for invalid wakeups MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Wanpeng Li Cc: Radim Krčmář CC: Paolo Bonzini CC: Cornelia Huck Signed-off-by: Christian Borntraeger Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 7 ++++--- 1 file 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 && -- 2.20.1