Messages in this thread |  | | | Date | Thu, 8 May 2008 16:19:52 -0700 | | From | "Paul E. McKenney" <> | | Subject | Re: [PATCH -mm][v2] ratelimit rewrite |
On Thu, May 08, 2008 at 12:25:14PM -0700, Andrew Morton wrote:
> On Tue, 6 May 2008 10:25:58 +0800
> Dave Young <hidave.darkstar@gmail.com> wrote:
>
> > static inline void rcu_enter_nohz(void)
> > {
> > + static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
> > smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
> > __get_cpu_var(rcu_dyntick_sched).dynticks++;
> > - WARN_ON_SECS(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, 10);
> > + WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs);
> > }
> >
> > static inline void rcu_exit_nohz(void)
> > {
> > + static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
> > __get_cpu_var(rcu_dyntick_sched).dynticks++;
> > smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
> > - WARN_ON_SECS(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1), 10);
> > + WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
> > + &rs);
>
> Why are we altering the RCU code in this patch, btw? It seems fairly
> random that we happened to choose these particular WARN_ONs. Do they have
> a history of triggering?
Yep -- there was a bug in this code a few months ago that was the
motivation for Dave's WARN_ON_RATELIMIT(). The bug has since been fixed,
so I would not expect this to trigger anymore, though.
Thanx, Paul
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