Messages in this thread | | | Subject | Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.51-12 | From | Peter Zijlstra <> | Date | Sat, 09 Jul 2005 23:24:03 +0200 |
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On Fri, 2005-07-08 at 13:12 -0700, William Weston wrote: > On Fri, 8 Jul 2005, Ingo Molnar wrote: > > > could you check whether the priority leakage happens if you disable SMP? > > (if you can reproduce it easily) > > No priority leakages have been seen with UP configs on any of the > machines I've been testing. > > The leakage is not hard to reproduce under SMT: start up jackd from a > text vc with an rt prio of 60 (or some unique prio above the IRQ threads), > then restart X and login. After several minutes, X and all of its > children will be running at whatever prio jackd was started at (but still > SCHED_NORMAL). Eventually, init, a handful of SCHED_NORMAL kernel > threads, and other random processes are all running at the same priority. > When reset to default priority with chrt or schedtool, these processes > eventually revert back to the leaked priority level. When jackd is > stopped, the priorities stay in their elevated state. If jackd is not > started before logging in to X, then the priority of one of the SCHED_FF > kernel threads is leaked to other processes in the same manner. >
I can reproduce priority leakage on my SMP system; any userspace process chrt'ed up and a lot will follow. This makes the system very unresponsive when doing a make -j5. Verified on 51-{6,18,23}.
-- Peter Zijlstra <a.p.zijlstra@chello.nl>
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