lkml.org 
[lkml]   [2015]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH v7 2/3] KVM: dynamic halt-polling
From
Date


On 05/09/2015 00:38, Wanpeng Li wrote:
>>
>> @@ -1940,11 +1975,16 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
>> * arrives.
>> */
>> if (kvm_vcpu_check_block(vcpu) < 0) {
>> + polled = true;
>> ++vcpu->stat.halt_successful_poll;
>> - goto out;
>> + break;
>> }
>> cur = ktime_get();
>> } while (single_task_running() && ktime_before(cur, stop));
>> +
>> + poll_ns = ktime_to_ns(cur) - ktime_to_ns(start);
>> + if (polled)
>> + goto out;
>>
>
> Please move poll_ns caculation under if() when you applied, as I
> explained in reply to v6.

You can do much more than just that, the patch reduces to this:

@@ -1929,6 +1963,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
ktime_t start, cur;
DEFINE_WAIT(wait);
bool waited = false;
+ u64 block_ns;

start = cur = ktime_get();
if (vcpu->halt_poll_ns) {
@@ -1961,7 +1996,21 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
cur = ktime_get();

out:
- trace_kvm_vcpu_wakeup(ktime_to_ns(cur) - ktime_to_ns(start), waited);
+ block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
+
+ 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);
+ }
+
+ trace_kvm_vcpu_wakeup(block_ns, waited);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_block);

Paolo


\
 
 \ /
  Last update: 2015-09-06 17:01    [W:0.097 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site