Re: [RFC][PATCH 1/3] Introduce a workqueue to deliver PIT timer interrupts.

Avi Kivity
2010-06-09T14:16:52Z

On 06/09/2010 04:23 PM, Marcelo Tosatti wrote:
>
>> Is there any chance that using a workqueue might help the problem of
>> hrtimers firing too quickly? I wanted to return HR_NORESTART from
>> pit_timer_fn always, then restart the hrtimer on delivery, but
>> because of unreliable delivery, it wasn't clear how to do that.
>>
>> Perhaps the workqueue can be used to restart the timer instead,
>> avoiding problems of impossibly small timeouts causing hrtimers to
>> run amok.
>>
> It should be rearmed on ACK ideally. How come delivery is unreliable?
>
> BTW, a massive amount of hrtimers (_single_ non-tickless 32-vcpu guest
> with LAPIC) results in:
>
> hrtimer: interrupt took 122448 ns
>
> in the host. So don't even need impossibly small timeouts :(
>

Any idea where that came from? Even looping on vcpus, that took 4 usec
per vcpu.

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error compiling committee.c: too many arguments to function