Re: [patch] Voluntary Preempt additions

[Ingo Molnar <mingo@elte.hu>]

* Daniel Walker <dwalker@mvista.com> wrote:

> This is in addition to voluntary preempt U5 . So, first apply up to
> Voluntary Preempt U4 , then apply this patch. I'll release for U5 as
> soon as it's formally released. 

i've released U5 an hour ago.

> We are releasing the following new features,
>                                                                                       
> - Architecture independent mutex with priority inheritance. Note, we
> have only tested this in x86.

there's new generic mutex code in -U5 which covers all the locking
primitives: semaphores, rw-semaphores, spinlock-mutexes and
rwlock-mutexes. PI should be done by improving the existing
rwsem-generic.c code.

> - Modified latency tracer to trace non-preemptable mutex locking , in
> /proc/lock_trace

hm, what is this good for? It is illegal to enter a schedulable section 
with preemption disabled and there we currently dump a trace of all 
critical sections held - this should be enough to pinpoint the bug.

> - Added two new locking functions _mutex_lock_cpu and
> _mutex_unlock_cpu.

hm, they are unused right now - what will they be used for?

	Ingo