Re: [PATCH tip/core/rcu 10/20] rcu: Provide diagnostic option to slow down grace-period initialization

Paul E. McKenney
2015-03-04T14:59:49Z

On Wed, Mar 04, 2015 at 11:54:37AM +0100, Paul Bolle wrote:
> All I spotted is a silly typo.
>
> Paul E. McKenney schreef op di 03-03-2015 om 09:43 [-0800]:
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -1257,6 +1257,30 @@ config RCU_TORTURE_TEST_RUNNABLE
> > Say N here if you want the RCU torture tests to start only
> > after being manually enabled via /proc.
> >
> > +config RCU_TORTURE_TEST_SLOW_INIT
> > + bool "Slow down RCU grace-period initialization to expose races"
> > + depends on RCU_TORTURE_TEST
> > + help
> > + This option makes grace-period initialization block for a
> > + few jiffies between initializing each pair of consecutive
> > + rcu_node structures. This helps to expose races involving
> > + grace-period initialization, in other words, it makes your
> > + kernel less stable. It can also greatly increase grace-period
> > + latency, especially on systems with large numbers of CPUs.
> > + This is useful when torture-testing RCU, but in almost no
> > + other circumstance.
> > +
> > + Say Y here if you want your system to crash and hang more often.
>
> (Did you ever consider going into marketing?)

"Get your cold dead fish here!!! And what is this 'sashimi' you speak of?"

But yes, I really do not want distros to enable this one. Unless it
is some sort of Ridiculously Unstable Linux distro. ;-)

> > + Say N if you want a sane system.
> > +
> > +config RCU_TORTURE_TEST_SLOW_INIT_DELAY
> > + int "How must to slow down RCU grace-period initialization"
>
> s/must/much/

Good catch, fixed!

Thanx, Paul

> > + range 0 5
> > + default 0
> > + help
> > + This option specifies the number of jiffies to wait between
> > + each rcu_node structure initialization.
> > +
> > config RCU_CPU_STALL_TIMEOUT
> > int "RCU CPU stall timeout in seconds"
> > depends on RCU_STALL_COMMON
>
>
> Paul Bolle
>