Re: [linux-audio-dev] Re: [announce] [patch] Voluntary KernelPreemption Patch

[Andrew Morton]

Andrea Arcangeli <andrea@xxxxxxx> wrote:
>
> > And it's currently OK to add a might_sleep() to (say) an inline path which
> > is expended a zillion times because we know it'll go away for production
> > builds.  If those things become cond_resched() calls instead, the code
> > increase will be permanent.
> 
> this is exactly why I'm making this change: so you can still add
> might_sleep in a inline path expected to run a zillion times. With
> Ingo's change you would be doing cond_sched internally to might_sleep, I
> do the other way around so might_sleep remains a debugging statement.

OK.


cond_resched() is usually a waste of space with CONFIG_PREEMPT.  It might
make sense to define a cond_resched_if_not_preempt thingy, which only does
things if !CONFIG_PREEMPT.  We'd still need to use cond_resched() inside
lock_kernel().

> 
> > I've yet to go through Arjan's patch - I suspect a lot of it is not needed.
> 
> Arjan's or Ingo's? I've seen Ingo's patch but maybe I missed Arjan's one.

I think Ingo's patch includes Arjan's one.  Ingo's patch apparently breaks
ext3.  I have a bunch of ext3 and other fixes here, but there's still an occasional
problem on SMP.

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