Messages in this thread | | | Date | Mon, 16 Aug 1999 17:18:01 +0100 (GMT) | From | Matthew Kirkwood <> | Subject | Re: Problems writting a CHAR Driver with interruptible_sleep (wait_ queu e) |
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On Mon, 16 Aug 1999, Raul Dias wrote:
> > It's not uncommon just to busy wait for that amount of time: > > usleep(100); > > But that would "hang" the machine during this time, right?
Yep.
> It will be thousands of readings in a second, so I can't "hang" the > machine.
Oh. Out of curiosity, how do you expect to do thousands of reads per second when you have a thousandth of a second between them? :)
Seriously, you probably want to look at the PC speaker driver patch - this did some pretty hairy modifications to the timer interrupt stuff to have it use the RTC instead of the usual PC timer chip, I think.
It seems to have disappeared from its previous home, but dave@infradead.org was last to be seen with it.
> >> Can I count the time with a higher precision than with jiffies? > >> I need to keep track of the time on every read, but a jiffie is too > >> slow. > > > > You can use the TSC, but that screws up portability. > > portability between platafforms or between kernels?
Platforms. The TSC is an i386 thing, though other architectures often have similar features. Either way, it's only really useful for busy-waiting and accurate timing measurements anyway.
> Where can I find more info about it?
grep the source for CONFIG_M586TSC, or visit www.intel.com.
Matthew.
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