On Tue, 2006-06-06 at 14:31 -0400, Joshua Boyd wrote: > setpriority(PRIO_PROCESS, 0, -20); > > I was under the impression that that set priority to a "realtime" > priority, although rereading the man page I don't see any specific > correlation listed between -20 and realtime. there is no relationship whatsoever. > I also do: sched_setscheduler(0, SCHED_FIFO, &sp); on POSIX-ish operating systems, there are two orthogonal aspects to scheduling: scheduling class and scheduling priority. priority only ranks different execution contexts (kernel threads) within the *same* scheduling class - it has no impact when a scheduling decision has to be made between two execution contexts in two different classes. put differently, you can leave yourself in SCHED_OTHER (the default class) and raise your priority to the maximum, but you will never ever be scheduled to run if there is a SCHED_FIFO thread ready to run even if its numerical priority is lower than yours. there is no reason to use setpriority() for realtime work: sched_setscheduler's parameter argument defines the priority. --p
