Re: [PATCH] 2.6.17-rt add clockevent to ixp4xx

[Daniel Walker]

On Thu, 2006-07-13 at 10:53 +0000, Milan Svoboda wrote:
> Hello,
> 
> there are patches that enable clock event on ixp4xx platform. This should
> enable high resolution timers... Option for hrtimers in menuconfig is 
> also enabled.
> 
> I tested it on nanosleep test program (included in attachments) and obtained
> this results:
> 
> requested: 899000 us, got: 899159 us, diff: -159 us
> requested: 897000 us, got: 897209 us, diff: -209 us
> requested: 895000 us, got: 899803 us, diff: -4803 us
> requested: 893000 us, got: 899425 us, diff: -6425 us
> requested: 891000 us, got: 899806 us, diff: -8806 us
> requested: 889000 us, got: 890142 us, diff: -1142 us
> requested: 887000 us, got: 889873 us, diff: -2873 us
> requested: 885000 us, got: 888096 us, diff: -3096 us

I'd turn off some of the debugging options, and retest. For instance,
the pi-list debugging option will cause arbitrary latency, which you
seem to show in your results. Normally with PREEMPT_RT turned on you
would expect the timers to trigger within a constant amount of time from
when they are suppose to.

Daniel

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