Re: [Xen-devel] VCPUOP_set_periodic_timer

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 14/11/2013 21:18, Simon Martin wrote:

Hi all,

 

I need a periodic timer running at ideally at 125 microseconds and at least 500 microseconds. I've just found the VCPUOP_set_periodic_timer, however there is a comment saying "periods less than one millisecond may not be supported".

 

I will be running on an x64 machine. Is this supported? If not, is there any alternate means of generating a fast interrupt?

 

Regards.

What is the usecase here?  125us is very short indeed.  Xen certainly cant guarantee anything more accurate than 50us.  Unless the affected vcpu is running uncontested on the hardware, there is very little chance that the vcpu will indeed be woken up again in 125us.

It sounds as if you are looking for some pseudo realtime system, at which point you might want to consider a different scheduler.

~Andrew

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