Messages in this thread | | | Subject | RE: 2.6.11 timeval_to_jiffies() wrong for ms resolution timers | Date | Wed, 25 May 2005 13:16:45 -0600 | From | "Davda, Bhavesh P \(Bhavesh\)" <> |
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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 | bhavesh@avaya.com
> -----Original Message----- > From: Davda, Bhavesh P (Bhavesh) > Sent: Wednesday, May 25, 2005 1:07 PM > To: 'Chris Friesen'; 'george@mvista.com' > Cc: 'linux-kernel@vger.kernel.org' > Subject: RE: 2.6.11 timeval_to_jiffies() wrong for ms > resolution timers > > > -----Original Message----- > > From: Chris Friesen [mailto:cfriesen@nortel.com] > > Sent: Wednesday, May 25, 2005 12:08 PM > > To: george@mvista.com > > Cc: Davda, Bhavesh P (Bhavesh); linux-kernel@vger.kernel.org > > 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 | bhavesh@avaya.com > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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