Messages in this thread | | | Date | Wed, 6 Jul 2005 18:26:35 -0700 (PDT) | From | William Weston <> | Subject | Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.50-24 |
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On Sun, 3 Jul 2005, Ingo Molnar wrote:
> ok, found a bug that could explain the situation: mutex sleeps+wakeups > were incorrectly credited as 'interactive sleep' periods, causing the dd > processes to be boosted incorrectly. The dd processes created a workload > in which they blocked each other in such a pattern that they got boosted > periodically, starving pretty much every other task. > > the fix is significant and affects alot of workloads, and should further > improve interactivity in noticeable ways. I'm not 100% sure it solves > all the starvation problems (e.g. how could normal-prio dd tasks starve > the SCHED_FIFO irq threads that drove SysRq?), but the results so far > look promising. > > i've uploaded the -50-45 patch, can you under this kernel trigger a > 'meltdown' on your SMT box?
Still looking into this issue on -51-06. Found something really odd: SCHED_NORMAL tasks will start to inherit the priority value of some other SCHED_FIFO task. If JACK is started at a given SCHED_FIFO priority, X and all of its children will inherit the same priority value after login. Other random processes will inherit this, too -- sometimes init...
SCHED_NORMAL tasks suddenly inheriting priority values in the range normally reserved for SCHED_FIFO could explain at least part of the meltdown I've been seeing. Any thoughts?
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