El Mon, Mar 16, 2009 at 01:03:35PM +0300 Denis Borisevich ha dit: > 2009/3/16 Razvan Deaconescu <razvan@xxxxxxxxxxxxxxxxxx>: > > On Mon, 2009-03-16 at 00:41 +0300, Denis Borisevich wrote: > >> Hi! > >> Is there any way to achieve a timeout of say 10 usecs in kernel module? > > > > See udelay[1]. Please note that it does busy-waiting (you can't > > block/put to sleep the current process for periods less than 1000/HZ > > milliseconds). > > > > Razvan > > > > [1] http://lxr.linux.no/linux+v2.6.28.7/arch/x86/include/asm/delay.h#20 > > > Hmm..busy-wait is not good for my situation. Is there any way to > achieve these little timeouts with RT_PREEMPT patch? user space processes can use nanosleep() for sleeping for short times, though the kernel only guarantees that the process will sleep *at least* the specified time. the implementation of nanosleep() uses hrtimer_nanosleep() to achieve this, maybe you could try something similar: http://lxr.linux.no/linux+v2.6.28/kernel/hrtimer.c#L1632 10 usecs is a very short time for sleeping, i'm not sure if the kernel can provide this granularity. probably your task needs to have rt priority to be re-scheduled after such a short period. ftrace (Documentation/ftrace.txt) can be useful to determine whether the real sleep time is near to the period you pretend. -- Matthias Kaehlcke Embedded Linux Engineer Barcelona Someone has said that it requires less mental effort to condemn than to think (Emma Goldman) .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
