Re: [Xen-devel] VCPUOP_set_periodic_timer

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 15/11/2013 13:13, "Andrew Cooper" <andrew.cooper3@xxxxxxxxxx> wrote:

>    
> On 15/11/13 13:10, Keir Fraser wrote:
>  
>  
>>   Re: Re[4]: [Xen-devel] VCPUOP_set_periodic_timer You¹ll have to measure to
>> confirm, but if the core is dedicated to your vcpu then there is no reason
>> there should be 50us jitter. Also there is not much point playing with
>> different schedulers ? if there are no other vcpus schedulable on the cpu,
>> the scheduler can¹t have multiple runnable vcpus to choose between.
>>  
>>   -- Keir
>>  
>  
>  The deadline timer code as up to 50us of slop when calculating when to wake
> up and when timers expire.  It is somewhat poor, and is certainly an area in
> need of improvement.

Forgot about that. For real-time applications, timer_slop=0 on the Xen
command line will turn it off. But there could certainly be other gotchas
lurking; actual performance needs to be measured.

 -- Keir

>  ~Andrew
>  



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