Re: [PATCH] timers: Fix usleep_range() in the context of wake_up_process()

[Andreas Mohr]

On Mon, Oct 10, 2016 at 01:12:39PM -0700, Doug Anderson wrote:
> Hi,
> 
> On Mon, Oct 10, 2016 at 1:04 PM, Brian Norris <briannorris@xxxxxxxxxxxx> wrote:
> > I believe 'min' is unmodified throughout, and therefore 'kmin' is
> > computed to be the same minimum timeout in each loop. Shouldn't this be
> > decreasing on each iteration of the loop? (i.e., either your compute
> > 'kmin' differently here, or you recompute 'min' based on the elapsed
> > time?)
> 
> Yes, I stupidly changed something at the last second and then didn't
> test again after my stupid change.  Fix coming soon with all comments
> addressed.  Sorry for posting broken code.  :( :( :(

With a loop style that is actively re-calculating things,
such implementations should then not fall into the trap of
basing the "next" value on "current" time,
thereby bogusly accumulating scheduling-based delays
with each new loop iteration etc.
(i.e., things should still be based on hard, precise termination according to
an *initially* calculated, *absolute*, *minimum* expiry time).

Andreas Mohr

-- 
GNU/Linux. It's not the software that's free, it's you.