At Tue, 8 May 2007 09:40:33 +0530, Srivatsa Vaddagiri wrote: > > On Tue, May 08, 2007 at 12:29:19PM +0900, Satoru Takeuchi wrote: > > > We used to be able to create kernel threads higher than any userspace > > > priority. If this is no longer true, I think that's OK: equal priority > > > still means we'll get scheduled, right? > > > > IF SCHED_RR, yes. However, if SCHED_FIFO, no. Such process doen't have > > timeslice > > and only relinquish CPU time voluntarily. > > yeah ..this is truly a problem if SCHED_FIFO user-space cpu hog task is > running at MAX_USER_RT_PRIO (which happens to be same as max real-time > priority kernel threads can attain - MAX_RT_PRIO). > > One option is to make MAX_USER_RT_PRIO < MAX_RT_PRIO. I am not sure what > semantics that will break (perhaps the real-time folks can clarify > that).
Sometimes I wonder at prio_array. It has 140 entries(from 0 to 139), and the meaning of each entry is as follows, I think. +-----------+-----------------------------------------------+ | index | usage | +-----------+-----------------------------------------------+ | 0 - 98 | RT processes are here. They are in the entry | | | whose index is 99 - sched_priority. | +-----------+-----------------------------------------------+ | 99 | No one use it? CMIIW. | +-----------+-----------------------------------------------+ | 100 - 139 | Ordinally processes are here. They are in the | | | entry whose index is (nice+120) +/- 5 | +-----------+-----------------------------------------------+ What's the purpose of the prio_array[99]? Once I exlore source tree briefly and can't found any kernel thread which uses this entry. Does anybody know? Regards, Satoru - 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/
