Messages in this thread | | | Date | Tue, 13 Sep 2005 18:01:31 +0200 (CEST) | From | Tim Schmielau <> | Subject | Re: HZ question |
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On Tue, 13 Sep 2005, Mark Hounschell wrote:
> On a 100HZ kernel ANY requested delay via udelay or > pthread_cond_timedwait of less than 10000usecs is unreliable and the the > actual results are totally unacceptable. > > On a 1000HZ kernel the number is 1000 usecs. > > I'm not asking the kernel running at 1000hz to actually give me 500 usec > delay if I ask. I do expect it to be at least 500 usec and within +- a > single HZ however.
The kernel just cannot guarantee the latter. Rounding is only one of many issues here. Do you also want to know about CONFIG_PREEMPT, SMP, current load, future load in order to estimate the delay you want to ask for?
OTOH, I'm not a soft real-time expert, so I'll stop commenting here.
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