Re: [PATCH 6/7] sched: Clean up preempt_enable_no_resched() abuse

Eliezer Tamir
2013-11-20T20:14:24Z

On 20/11/2013 20:15, Peter Zijlstra wrote:
> There are options (CONFIG_PREEMPT_RCU) that allow scheduling while
> holding rcu_read_lock().
>
> Also, preempt_enable() only schedules when its possible to schedule, so
> calling it when you know you cannot schedule is no issue.
>

I have no issue with you changing busy_loop_us_clock() to use a regular
preempt enable.

I think that we still need to only do this if config preempt debug
is on. When it's off we should use the alternate implementation.
We are silencing a warning, but this is a performance critical path,
and we think we know what we are doing.

I tried to explain this in the comments. If you think my comments are
not clear enough, I'm open to suggestions.

Cheers,
Eliezer