lkml.org 
[lkml]   [2009]   [May]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH][KVM][retry 1] Add support for Pause Filtering to AMD SVM

* Avi Kivity <avi@redhat.com> wrote:

>> +static int pause_interception(struct vcpu_svm *svm, struct kvm_run
>> *kvm_run)
>> +{
>> + /* Simple yield */
>> + vcpu_put(&svm->vcpu);
>> + schedule();
>> + vcpu_load(&svm->vcpu);
>> + return 1;
>> +
>
> Ingo, will this do anything under CFS, or will CFS note that
> nothing has changed in the accounting and reschedule us
> immediately?

The scheduler will yield to another task only if the current task
has become ineligible. I.e schedule() is largely a NOP on
TASK_RUNNING tasks (i.e. here).

I.e. this is a somewhat poor solution as far as scheduling goes. But
i'm wondering what the CPU side does. Can REP-NOP really take
thousands of cycles? If yes, under what circumstances?

Ingo


\
 
 \ /
  Last update: 2009-05-11 16:19    [W:0.308 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site