Der Herr Hofrat wrote: >>Ish Rattan wrote: >> >> >>>On Mon, 4 Feb 2002, Saikrishnan Krishnamurthy wrote: >>> >>> >>> >>>> 1) Is there any means in linux kernel to offer a kernel thread, a >>>>real-time priority. (I tried assigning the SCHED_RR and SCHED_FIFO to my >>>>threads and it would hang my computer not measuring anythin >>>> >>>> >>>Linux kernel has no notion of real-time and hence priority. >>> >> >>Uhh... are you smoking crack? >> >>I'm happy to acknowledge that scheduling latencies are rather uncertain >>but it definately knows and respects SCHED_RR and SCHED_FIFO. I use >>SCHED_FIFO for soft real-time tasks. They have been supported for a >>LOOOONG time! >> >> > > if that were so then you would define a thread being SCHED_RR and
> the box would drop dead as it would ONLY be handling THIS thread > and nothing else - even if you run a SCHED_RR/SCHED_FIFO thread > your lowest priority thread will get its slot in linux thus you > have a "statistical priority" but no absolut priority . No need > to smoke crack to understand this... Uh? If there is a higher priority SCHED_RR/SCHED_FIFO process ready to run it will preempt the lower priority SCHED_RR/SCHED_FIFO processes. The box will only drop dead (from the point of view of lower priority, time share processes) if the rt processes never sleep. This is what any prioritized system will do and is what it should do. This is not statistical priority. No offense, but have you guys ever tried standard linux prioritized scheduling? Since many seem to believe that it doesn't even exist, I have to assume not. Its no replacement for RTLinux on super low latencies or highly consistent latency, but it is there, does work and is very suitable for many tasks. However, you are dealing with typical latencies that are 3 orders of magnitude higher than RTLinux and worst case that are more like 5 orders of magnitude worse. ...but that is just fine for many tasks. > hofrat Ty -- Tyson D Sawyer iRobot Corporation Senior Systems Engineer Military Systems Division [EMAIL PROTECTED] Robots for the Real World 603-532-6900 ext 206 http://www.irobot.com -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/
