| Message ID | 1572060239-17401-4-git-send-email-zhenzhong.duan@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | misc fixes on halt-poll code both KVM and guest | expand |
On Sat, Oct 26, 2019 at 11:23:57AM +0800, Zhenzhong Duan wrote: > When (block_ns == vcpu->halt_poll_ns), there is not a margin so that > vCPU may still get into block state unnecessorily. > > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> > --- > virt/kvm/kvm_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 1b6fe3b..48a1f1a 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2371,7 +2371,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) > if (!vcpu_valid_wakeup(vcpu)) { > shrink_halt_poll_ns(vcpu); > } else if (halt_poll_ns) { > - if (block_ns <= vcpu->halt_poll_ns) > + if (block_ns < vcpu->halt_poll_ns) > ; > /* we had a short halt and our poll time is too small */ > else if (block_ns < halt_poll_ns) > -- > 1.8.3.1 Makes sense.
On 01/11/19 22:16, Marcelo Tosatti wrote: > if (!vcpu_valid_wakeup(vcpu)) { > shrink_halt_poll_ns(vcpu); > } else if (halt_poll_ns) { > - if (block_ns <= vcpu->halt_poll_ns) > + if (block_ns < vcpu->halt_poll_ns) > ; > /* we had a short halt and our poll time is too small */ > else if (block_ns < halt_poll_ns) What about making this "if (!waited)"? The result would be very readable: if (!waited) ; /* we had a long block, shrink polling */ else if (block_ns > halt_poll_ns && vcpu->halt_poll_ns) shrink_halt_poll_ns(vcpu); /* we had a short halt and our poll time is too small */ else if (block_ns < halt_poll_ns && vcpu->halt_poll_ns < halt_poll_ns) grow_halt_poll_ns(vcpu); Paolo
On 2019/11/11 21:53, Paolo Bonzini wrote: > On 01/11/19 22:16, Marcelo Tosatti wrote: >> if (!vcpu_valid_wakeup(vcpu)) { >> shrink_halt_poll_ns(vcpu); >> } else if (halt_poll_ns) { >> - if (block_ns <= vcpu->halt_poll_ns) >> + if (block_ns < vcpu->halt_poll_ns) >> ; >> /* we had a short halt and our poll time is too small */ >> else if (block_ns < halt_poll_ns) > What about making this "if (!waited)"? The result would be very readable: > > if (!waited) > ; > /* we had a long block, shrink polling */ > else if (block_ns > halt_poll_ns && vcpu->halt_poll_ns) > shrink_halt_poll_ns(vcpu); > /* we had a short halt and our poll time is too small */ > else if (block_ns < halt_poll_ns && vcpu->halt_poll_ns < halt_poll_ns) > grow_halt_poll_ns(vcpu); This patch is dropped in v2 as it rarely happen in real scenario. Appreciate you reviewing v2 in https://lkml.org/lkml/2019/11/6/447 Thanks Zhenzhong
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1b6fe3b..48a1f1a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2371,7 +2371,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) if (!vcpu_valid_wakeup(vcpu)) { shrink_halt_poll_ns(vcpu); } else if (halt_poll_ns) { - if (block_ns <= vcpu->halt_poll_ns) + if (block_ns < vcpu->halt_poll_ns) ; /* we had a short halt and our poll time is too small */ else if (block_ns < halt_poll_ns)
When (block_ns == vcpu->halt_poll_ns), there is not a margin so that vCPU may still get into block state unnecessorily. Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)