Awefully sorry about the line-breaks (or absence thereof!)
Stupid Outlook that corporate IT forces us to use!
And I meant 20 ms, not 20 us, of course...
- Bhavesh
Bhavesh P. Davda | Distinguished Member of Technical Staff | Avaya |
1300 West 120th Avenue | B3-B03 | Westminster, CO 80234, U.S.A. |
Voice/Fax: (303) 538-4438 | [email protected]
> -----Original Message-----
> From: Davda, Bhavesh P (Bhavesh)
> Sent: Wednesday, May 25, 2005 1:07 PM
> To: 'Chris Friesen'; '[email protected]'
> Cc: '[email protected]'
> Subject: RE: 2.6.11 timeval_to_jiffies() wrong for ms
> resolution timers
>
> > -----Original Message-----
> > From: Chris Friesen [mailto:[email protected]]
> > Sent: Wednesday, May 25, 2005 12:08 PM
> > To: [email protected]
> > Cc: Davda, Bhavesh P (Bhavesh); [email protected]
> > Subject: Re: 2.6.11 timeval_to_jiffies() wrong for ms
> > resolution timers
> >
> > George Anzinger wrote:
> > > Chris Friesen wrote:
> >
> > >> What about telling it to wake up a jiffy earlier, then checking
> > >> whether the scheduling lag was enough to cause it to have
> > waited the
> > >> full specified time. If not, put it to sleep for another jiffy.
> >
> > > The user is, of course, free to do what ever they would like.
> >
> > I actually meant doing this in the kernel.
>
> Ditto.
>
> >
> > > For a
> > > more complete solution you might be interested in HRT (High Res
> > > Timers). See my signature below.
> >
> > Yep. One more patch to apply and worry about versions and
> > maintenance.
> > Not enough of a demand for us to be able to use it, at
> > least at this
> > point.
> >
> > Chris
>
> Ditto ditto :)
>
> BTW, this reminds me an aweful lot of TH2GT2G, and Deep
> Thought taking 7.5 million years to come up with the answer "42!"
>
> Me: Hey Deep Thought! What's 20 us converted into jiffies?
>
> Deep Thought: Let's see: after accounting for all kinds of
> underflow and overflow possibilities, and extending the
> operands to 64-bit to retain the best precision, and
> crunching through a few complex macros, the answer you're
> looking for is... Is... Is... "21!" The real problem is: You
> didn't ask me the right question. You should have asked me
> "What's 19 us converted into jiffies?"
>
> On a more serious note: what is a real-time (read
> SCHED_FIFO/SCHED_RR) task to use to get millisecond accuracy
> wakeup timing services from the kernel? i.e. what are the
> alternatives to setitimer() that wake up the task exactly at
> the interval that is requested of it? You mention high-res
> timers as a possibility, but in the form of a patch. What's
> available in mainline unpatched?
>
> Thanks
>
> - Bhavesh
>
>
>
> Bhavesh P. Davda | Distinguished Member of Technical Staff | Avaya |
> 1300 West 120th Avenue | B3-B03 | Westminster, CO 80234, U.S.A. |
> Voice/Fax: (303) 538-4438 | [email protected]
>
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