lkml.org 
[lkml]   [2005]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC] RCU and CONFIG_PREEMPT_RT progress, part 3
From
Date
On Wed, 2005-07-13 at 11:48 -0700, Paul E. McKenney wrote:
> Hello!
>
> Ported to CONFIG_PREEMPT_RT, and it actually boots! Running tests,

Good! :)

> working thus far. But thought I would post the patch and get feedback
> in the meantime, since I am not sure that my approach is correct.
> The questions:
>
> 1. Is use of spin_trylock() and spin_unlock() in hardirq code
> (e.g., rcu_check_callbacks() and callees) a Bad Thing?
> Seems to result in boot-time hangs when I try it, and switching
> to _raw_spin_trylock() and _raw_spin_unlock() seems to work
> better. But I don't see why the other primitives hang --
> after all, you can call wakeup functions in irq context in
> stock kernels...

I never use _raw_spin_*. I just declare the lock as a raw_spinlock_t
and the macro's determine to use them instead. So I just keep the
spin_lock in the code. Or do you mean that you get problems using the
spin_locks when the code is already defined as raw_spinlock_t?

>
> 2. Is _raw_spin_lock_irqsave() intended for general use? Its
> API differs from that of spin_lock_irqsave(), so am wondering
> if it is internal-use-only or something. I currently
> use it from process context to acquire locks shared with
> rcu_check_callbacks().

I would assume not, but Ingo would be better at answering this.

>
> 3. Since SPIN_LOCK_UNLOCKED now takes the lock itself as an
> argument, what is the best way to initialize per-CPU
> locks? An explicit initialization function, or is there
> some way that I am missing to make an initializer?

Ouch, I just notice that (been using an older version for some time).

Ingo, is this to force the initialization of the lists instead of at
runtime?


-- Steve


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

\
 
 \ /
  Last update: 2005-07-13 21:29    [W:0.103 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site