Re: windows acpi time drift

[Anthony Liguori <anthony@codemonkey.ws>]

Dor Laor wrote:
> 2. The other option is to have an accurate userspace timer (userspace
> hrtimer exist >= 2.6.24) and to add interface to pic/apic to queue
> pending irqs by the pit/rtc.
> The pending queue can be a simple atomic counter per irq.
>   

So this may explain why I see no appreciable benefit from using the 
in-kernel PIT verses using the userspace PIT and -tdf.  I'm using a 
2.6.24 host kernel and QEMU by default will use the "unix" time source 
which will use setitimer.  IIUC, itimer will use hrtimers.

So if there isn't an appreciate CPU utilization improvement and there 
isn't an increased accuracy, there won't be an improvement.

Do ya'll see an improvement playing multimedia on a 2.6.24 host with the 
in-kernel PIT?

Regards,

Anthony Liguori

> Note that we also need support for older host kernels.
>
> Before implementing yet another in-kernel device I like to hear
> opinions. 
> Regards,
> Dor.
>
>
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