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RE: [Xen-devel] [PATCH 0/2] range timer support

Yu Ke wrote:
> 2008/10/29 Keir Fraser <keir.fraser@xxxxxxxxxxxxx>:
>> On 29/10/08 02:29, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>>> Yes, this is a valid concern. Simplicity is better if we're not sure
>>> the gain by making things complex. I agree that a central slop
>>> control is cleaner here. In the meantime how about also adding a
>>> flag to disable slop per-timer base? Then timers with stricter
>>> delivery requirement can add this flag even when global slop is
>>> enabled. 
>>> Or may be this control can be exposed to user by domctl interface,
>>> as a per-domain configurable option.
>> I actually wonder whether we would get similar to your 5% win by just
>> increasing the SLOP parameter to a fixed 1ms. That would equal your
>> worst-case slop in the second range-timer patch for vpt timers, and
>> I don't really see why any timer in Xen wouldn't be able to deal
>> with that. 
> Increasing SLOP to 1ms should have the the similar 5% gain, as your
> analysis, it is the worst case of range timer application in vpt. I
> can redo the measurement to double confirm.

I have finished the measurement, when TIME_SLOP increase to 1ms, there is 
similar power consumption gain, this time it is 4% (14.0W vs 14.6W) . By theory 
1ms TIMER_SLOP should have more gain than the range timer. The diferrence may 
be due to the test environment noise.

Best Regards
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