On Thu, Jun 18, 2020 at 03:40:58PM -0700, Paul E. McKenney wrote:
> On Thu, Jun 18, 2020 at 04:29:54PM -0400, Joel Fernandes (Google) wrote:
> > This is useful to check for any improvements or degradation related to
> > number of GP kthread wakeups during testing.
> >
> > Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org>
>
> This was a good way to collect the data for your testing, but
> we can expect rcutorture to only do so much. ;-)
np, I will push this one into a git tag for the next time I need it ;)
thanks,
- Joel
> Thanx, Paul
>
> > ---
> > kernel/rcu/Kconfig.debug | 1 +
> > kernel/rcu/rcu.h | 2 ++
> > kernel/rcu/rcutorture.c | 23 ++++++++++++++++++++++-
> > kernel/rcu/tree.c | 7 +++++++
> > 4 files changed, 32 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
> > index 3cf6132a4bb9f..3323e3378af5a 100644
> > --- a/kernel/rcu/Kconfig.debug
> > +++ b/kernel/rcu/Kconfig.debug
> > @@ -50,6 +50,7 @@ config RCU_TORTURE_TEST
> > select TASKS_RCU
> > select TASKS_RUDE_RCU
> > select TASKS_TRACE_RCU
> > + select SCHEDSTATS
> > default n
> > help
> > This option provides a kernel module that runs torture tests
> > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
> > index cf66a3ccd7573..7e867e81d9738 100644
> > --- a/kernel/rcu/rcu.h
> > +++ b/kernel/rcu/rcu.h
> > @@ -511,6 +511,7 @@ srcu_batches_completed(struct srcu_struct *sp) { return
> > 0; }
> > static inline void rcu_force_quiescent_state(void) { }
> > static inline void show_rcu_gp_kthreads(void) { }
> > static inline int rcu_get_gp_kthreads_prio(void) { return 0; }
> > +static inline struct task_struct *rcu_get_main_gp_kthread(void) { return
> > 0; }
> > static inline void rcu_fwd_progress_check(unsigned long j) { }
> > #else /* #ifdef CONFIG_TINY_RCU */
> > bool rcu_dynticks_zero_in_eqs(int cpu, int *vp);
> > @@ -519,6 +520,7 @@ unsigned long rcu_exp_batches_completed(void);
> > unsigned long srcu_batches_completed(struct srcu_struct *sp);
> > void show_rcu_gp_kthreads(void);
> > int rcu_get_gp_kthreads_prio(void);
> > +struct task_struct *rcu_get_main_gp_kthread(void);
> > void rcu_fwd_progress_check(unsigned long j);
> > void rcu_force_quiescent_state(void);
> > extern struct workqueue_struct *rcu_gp_wq;
> > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> > index d0d265304d147..959a1f84d6904 100644
> > --- a/kernel/rcu/rcutorture.c
> > +++ b/kernel/rcu/rcutorture.c
> > @@ -23,6 +23,7 @@
> > #include <linux/rcupdate_wait.h>
> > #include <linux/interrupt.h>
> > #include <linux/sched/signal.h>
> > +#include <linux/sched/stat.h>
> > #include <uapi/linux/sched/types.h>
> > #include <linux/atomic.h>
> > #include <linux/bitops.h>
> > @@ -460,9 +461,29 @@ static void rcu_sync_torture_init(void)
> > INIT_LIST_HEAD(&rcu_torture_removed);
> > }
> >
> > +unsigned long rcu_gp_nr_wakeups;
> > +
> > +static void rcu_flavor_init(void)
> > +{
> > + rcu_sync_torture_init();
> > +
> > + /* Make sure schedstat is enabled for GP thread wakeup count. */
> > + force_schedstat_enabled();
> > + rcu_gp_nr_wakeups = rcu_get_main_gp_kthread()->se.statistics.nr_wakeups;
> > +}
> > +
> > +static void rcu_flavor_cleanup(void)
> > +{
> > + unsigned long now_nr =
> > rcu_get_main_gp_kthread()->se.statistics.nr_wakeups;
> > +
> > + pr_alert("End-test: Cleanup: Total GP-kthread wakeups: %lu\n",
> > + now_nr - rcu_gp_nr_wakeups);
> > +}
> > +
> > static struct rcu_torture_ops rcu_ops = {
> > .ttype = RCU_FLAVOR,
> > - .init = rcu_sync_torture_init,
> > + .init = rcu_flavor_init,
> > + .cleanup = rcu_flavor_cleanup,
> > .readlock = rcu_torture_read_lock,
> > .read_delay = rcu_read_delay,
> > .readunlock = rcu_torture_read_unlock,
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index c3bae7a83d792..a3a175feb310a 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -175,6 +175,13 @@ int rcu_get_gp_kthreads_prio(void)
> > }
> > EXPORT_SYMBOL_GPL(rcu_get_gp_kthreads_prio);
> >
> > +/* Retrieve RCU's main GP kthread task_struct */
> > +struct task_struct *rcu_get_main_gp_kthread(void)
> > +{
> > + return rcu_state.gp_kthread;
> > +}
> > +EXPORT_SYMBOL_GPL(rcu_get_main_gp_kthread);
> > +
> > /*
> > * Number of grace periods between delays, normalized by the duration of
> > * the delay. The longer the delay, the more the grace periods between
> > --
> > 2.27.0.111.gc72c7da667-goog
> >
