On Thu, 2006-01-19 at 10:42 -0500, Gu, John A. (US SSA) wrote: > Guys, > > Is there a way to program a timer with the resolution higher than 10 > msec? I need 100 usec resolution in either kernel or user space. > udelay( ) uses software loop to achieve the time delay. Is there a > better interrupt driven wakeup function? There are several ways to do this, but they are not (yet) supported by the standard kernel as found on Fedora (or any other distro). One way is to use a realtime extension like rtlinux or RTAI. These extensions offer latency that is near the actual hardware latency of your machine, which is between 15 and 50 microseconds. More information on RTAI can be found under www.rtai.org. Another way is to use the realtime patches from Ingo and Thomas. They offer also a way higher timer resolution and lower latency than the normal kernel. Some parts of their patches are already in the next kernel, so they seem to be the way to go, if latency of about 50-200 is acceptable. Since this is all developer work, you will have to search the Linux kernel mailing list for more info. The patches itself can be found under http://people.redhat.com/mingo/realtime-preempt/ You also might want to critically look at your software/hardware on why you need those timers. Maybe if you explain what you are trying to do someone has a better/different solution for you that does work with the normal kernel. - Erwin
