Re: [PATCH] small optimization to update_curr_rt

[Dimitri Sivanich <sivanich@sgi.com>]

On Fri, Oct 31, 2008 at 06:10:13AM -0700, Steven Noonan wrote:
> On Fri, Oct 31, 2008 at 6:03 AM, Dimitri Sivanich <sivanich@sgi.com> wrote:
> > A very minor improvement, but might it be better to check sched_rt_runtime(rt_rq)
> > before taking the rt_runtime_lock?
> 
> Is it possible that the attribute sched_rt_runtime is checking could
> change by the time it acquires the lock? If not, should be fine, I
> think.
>

Steve,

While it might be possible for it to change in that instant, I don't know if it matters.

If the runtime value should change to RUNTIME_INF in that instant, it will be caught in sched_rt_runtime_exceeded().  If it changed from RUNTIME_INF to a lower value, I doubt it would matter much, as at most one more rt_rq value wouldn't be checked.  Either way some rt_rq values would have been checked during the loop and some would not.