Re: [PATCH] rcutorture: Replace schedule_timeout*() 1 jiffie waits with HZ/20

[Paul E. McKenney]

On Fri, Aug 25, 2023 at 02:55:38AM +0000, Joel Fernandes wrote:
> On Wed, Aug 23, 2023 at 02:07:55PM -0700, Paul E. McKenney wrote:
> > On Wed, Aug 16, 2023 at 08:49:12PM +0000, Joel Fernandes (Google) wrote:
> > > In the past, we see that spinning on schedule_timeout* with a wait of 1
> > > jiffie can hang the kernel. See d52d3a2bf408 ("torture: Fix hang during
> > > kthread shutdown phase").
> > > 
> > > Recently again it showed up in torture's stutter code as well. The behavior is
> > > the the function may instantly return and never go to sleep preempting whatever
> > > was running under it.
> > > 
> > > To prevent future issues, apply the same fix mentioned in the above
> > > commit d52d3a2bf408 to more places.
> > > 
> > > I took care to only apply it to places where I thought it made sense.
> > > 
> > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> > 
> > Hearing no objections, I applied this for further review and testing.
> > 
> > In the future, should some of these become hrtimers?
> 
> Yes they certainly could be but we don't need these ones to be high
> resolution AFAICS and the jiffie granularity should be good.

True, but wouldn't avoiding the repeated wakeups, even at the lower
frequency, be of some value?

							Thanx, Paul