Re: CONFIG_PEEMPT_RT_FULL vs. CONFIG_PREEMPT_RTB

[Remy Bohmer]

Hi,

> Besides of the cpu load i also found out that with rt11 i can again wake up
> usermode from a IRQF_NO_THREAD waiting on a waitqueue. So the steps outlined
> in this mail http://www.spinics.net/lists/linux-rt-users/msg06834.html do not
> seem to be neccessary anymore? Or does this create an error and than some high
> load?

Try running with CONFIG_DEBUG_SPINLOCK_SLEEP and you would probably
see some errors...

If you have CONFIG_PREEMPT_RT_FULL set, then the __wake_up function of
the waitqueue runs into a spinlock. This spinlock will be converted to
a mutex since it is a regular spinlock, not a raw_spinlock. A
mutex-lock might sleep. Calling sleeping functions from hard-irq
context is illegal.

Kind regards,

Remy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/