2019-09-29 01:09:53

by Wanpeng Li

Subject: [PATCH v2] KVM: Don't shrink/grow vCPU halt_poll_ns if host side polling is disabled

From: Wanpeng Li <[email protected]>

Don't waste cycles to shrink/grow vCPU halt_poll_ns if host
side polling is disabled.

Acked-by: Marcelo Tosatti <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Signed-off-by: Wanpeng Li <[email protected]>
---
v1 -> v2:
* fix coding style

virt/kvm/kvm_main.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e6de315..9d5eed9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2359,20 +2359,23 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
kvm_arch_vcpu_unblocking(vcpu);
block_ns = ktime_to_ns(cur) - ktime_to_ns(start);

- 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->halt_poll_ns && block_ns > halt_poll_ns)
+ if (!kvm_arch_no_poll(vcpu)) {
+ if (!vcpu_valid_wakeup(vcpu)) {
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 &&
- block_ns < halt_poll_ns)
- grow_halt_poll_ns(vcpu);
- } else
- vcpu->halt_poll_ns = 0;
+ } else if (halt_poll_ns) {
+ if (block_ns <= vcpu->halt_poll_ns)
+ ;
+ /* we had a long block, shrink polling */
+ 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 &&
+ block_ns < halt_poll_ns)
+ grow_halt_poll_ns(vcpu);
+ } else {
+ vcpu->halt_poll_ns = 0;
+ }
+ }

trace_kvm_vcpu_wakeup(block_ns, waited, vcpu_valid_wakeup(vcpu));
kvm_arch_vcpu_block_finish(vcpu);
--
2.7.4

2019-10-08 01:08:51

by Wanpeng Li

Subject: Re: [PATCH v2] KVM: Don't shrink/grow vCPU halt_poll_ns if host side polling is disabled

ping,
On Sun, 29 Sep 2019 at 09:07, Wanpeng Li <[email protected]> wrote:
>
> From: Wanpeng Li <[email protected]>
>
> Don't waste cycles to shrink/grow vCPU halt_poll_ns if host
> side polling is disabled.
>
> Acked-by: Marcelo Tosatti <[email protected]>
> Cc: Marcelo Tosatti <[email protected]>
> Signed-off-by: Wanpeng Li <[email protected]>
> ---
> v1 -> v2:
> * fix coding style
>
> virt/kvm/kvm_main.c | 29 ++++++++++++++++-------------
> 1 file changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e6de315..9d5eed9 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2359,20 +2359,23 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> kvm_arch_vcpu_unblocking(vcpu);
> block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
>
> - 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->halt_poll_ns && block_ns > halt_poll_ns)
> + if (!kvm_arch_no_poll(vcpu)) {
> + if (!vcpu_valid_wakeup(vcpu)) {
> 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 &&
> - block_ns < halt_poll_ns)
> - grow_halt_poll_ns(vcpu);
> - } else
> - vcpu->halt_poll_ns = 0;
> + } else if (halt_poll_ns) {
> + if (block_ns <= vcpu->halt_poll_ns)
> + ;
> + /* we had a long block, shrink polling */
> + 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 &&
> + block_ns < halt_poll_ns)
> + grow_halt_poll_ns(vcpu);
> + } else {
> + vcpu->halt_poll_ns = 0;
> + }
> + }
>
> trace_kvm_vcpu_wakeup(block_ns, waited, vcpu_valid_wakeup(vcpu));
> kvm_arch_vcpu_block_finish(vcpu);
> --
> 2.7.4
>

2019-10-08 12:13:59

by Paolo Bonzini

Subject: Re: [PATCH v2] KVM: Don't shrink/grow vCPU halt_poll_ns if host side polling is disabled

On 29/09/19 03:06, Wanpeng Li wrote:
> From: Wanpeng Li <[email protected]>
>
> Don't waste cycles to shrink/grow vCPU halt_poll_ns if host
> side polling is disabled.
>
> Acked-by: Marcelo Tosatti <[email protected]>
> Cc: Marcelo Tosatti <[email protected]>
> Signed-off-by: Wanpeng Li <[email protected]>
> ---
> v1 -> v2:
> * fix coding style
>
> virt/kvm/kvm_main.c | 29 ++++++++++++++++-------------
> 1 file changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e6de315..9d5eed9 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2359,20 +2359,23 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> kvm_arch_vcpu_unblocking(vcpu);
> block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
>
> - 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->halt_poll_ns && block_ns > halt_poll_ns)
> + if (!kvm_arch_no_poll(vcpu)) {
> + if (!vcpu_valid_wakeup(vcpu)) {
> 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 &&
> - block_ns < halt_poll_ns)
> - grow_halt_poll_ns(vcpu);
> - } else
> - vcpu->halt_poll_ns = 0;
> + } else if (halt_poll_ns) {
> + if (block_ns <= vcpu->halt_poll_ns)
> + ;
> + /* we had a long block, shrink polling */
> + 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 &&
> + block_ns < halt_poll_ns)
> + grow_halt_poll_ns(vcpu);
> + } else {
> + vcpu->halt_poll_ns = 0;
> + }
> + }
>
> trace_kvm_vcpu_wakeup(block_ns, waited, vcpu_valid_wakeup(vcpu));
> kvm_arch_vcpu_block_finish(vcpu);
>

Queued, thanks.

Paolo