On Sat, 2005-01-22 at 10:48 +1100, Con Kolivas wrote: > utz lehmann wrote: > > Hi > > > > I dislike the behavior of the SCHED_ISO patch that iso tasks are > > degraded to SCHED_NORMAL if they exceed the limit. > > IMHO it's better to throttle them at the iso_cpu limit. > > > > I have modified Con's iso2 patch to do this. If iso_cpu > 50 iso tasks > > only get stalled for 1 tick (1ms on x86). > > Some tasks are so cache intensive they would make almost no forward > progress running for only 1ms.
Ok. The throttle duration can be exceed. What is a good value? 5ms, 10ms? > > > Fortunately there is a currently unused task prio (MAX_RT_PRIO-1) [1]. I > > Your implementation is not correct. The "prio" field of real time tasks > is determined by MAX_RT_PRIO-1-rt_priority. Therefore you're limiting > the best real time priority, not the other way around. Really? The task prios are (lower value is higher priority): 0 .. For SCHED_FIFO/SCHED_RR (rt_priority 99..1) 98 MAX_RT_PRIO-2 99 MAX_RT_PRIO-1 ISO_PRIO (rt_priority 0) 100 MAX_RT_PRIO .. For SCHED_NORMAL 139 MAX_PRIO-1 ISO_PRIO is between the SCHED_FIFO/SCHED_RR and the SCHED_NORMAL range. > > Throttling them for only 1ms will make it very easy to starve the system > with 1 or more short running (<1ms) SCHED_NORMAL tasks running. Lower > priority tasks will never run. > > Cheers, > Con - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
