| Message ID | 1463474962-5941-2-git-send-email-borntraeger@de.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 05/17/2016 10:49 AM, Christian Borntraeger wrote: > 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 Kr?má? <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> > --- > 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 fbd7698..dec1ed2 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); ^ hmpf. Small whitespace error. I can resend if wanted. > + 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 && > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 17/05/2016 15:54, Christian Borntraeger wrote: >> > - if (halt_poll_ns) { >> > + if (!vcpu_valid_wakeup(vcpu)) >> > + shrink_halt_poll_ns(vcpu); > ^ hmpf. Small whitespace error. I can resend if wanted. No need. Paolo >> > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 17 May 2016 10:49:22 +0200 Christian Borntraeger <borntraeger@de.ibm.com> wrote: > 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 Kr?má? <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> > --- > virt/kvm/kvm_main.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index fbd7698..dec1ed2 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 &&
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 Kr?má? <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> --- virt/kvm/kvm_main.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)