Re: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline

From: Dmitry Adamushko
Date: Fri Mar 07 2008 - 08:02:38 EST


Hi,

'watchdog' is of SCHED_FIFO class. The standard load-balancer doesn't
move RT tasks between cpus anymore and there is a special mechanism in
scher_rt.c instead (I think, it's .25 material).

So I wonder, whether __migrate_task() is still capable of properly
moving a RT task to another CPU (e.g. for the case when it's in
TASK_RUNNING state) without breaking something in the rt migration
mechanism (or whatever else) that would leave us with a runqueue in
the 'inconsistent' state...
(I've taken a quick look at the relevant code so can't confirm it yet)

maybe it'd be faster if somebody could do a quick test now with the
following line commented out in kernel/softlockup.c :: watchdog()

- sched_setscheduler(current, SCHED_FIFO, &param);


--
Best regards,
Dmitry Adamushko
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