On Thu, Aug 30, 2012 at 02:05:23PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <[email protected]> > > By default we don't want to enter into RCU extended quiescent > state while in userspace because doing this produces some overhead > (eg: use of syscall slowpath). Set it off by default and ready to > run when some feature like adaptive tickless need it. > > Signed-off-by: Frederic Weisbecker <[email protected]> > Cc: Alessio Igor Bogani <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Avi Kivity <[email protected]> > Cc: Chris Metcalf <[email protected]> > Cc: Christoph Lameter <[email protected]> > Cc: Geoff Levand <[email protected]> > Cc: Gilad Ben Yossef <[email protected]> > Cc: Hakan Akkan <[email protected]> > Cc: H. Peter Anvin <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Josh Triplett <[email protected]> > Cc: Kevin Hilman <[email protected]> > Cc: Max Krasnyansky <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Stephen Hemminger <[email protected]> > Cc: Steven Rostedt <[email protected]> > Cc: Sven-Thorsten Dietrich <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Josh Triplett <[email protected]> > kernel/rcutree.c | 5 ++++- > kernel/rcutree.h | 1 + > 2 files changed, 5 insertions(+), 1 deletions(-) > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index 8bbc7fb..e2fd370 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -210,6 +210,9 @@ EXPORT_SYMBOL_GPL(rcu_note_context_switch); > DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { > .dynticks_nesting = DYNTICK_TASK_EXIT_IDLE, > .dynticks = ATOMIC_INIT(1), > +#ifdef CONFIG_RCU_USER_QS > + .ignore_user_qs = true, > +#endif > }; > > static int blimit = 10; /* Maximum callbacks per rcu_do_batch. > */ > @@ -443,7 +446,7 @@ void rcu_user_enter(void) > > local_irq_save(flags); > rdtp = &__get_cpu_var(rcu_dynticks); > - if (!rdtp->in_user) { > + if (!rdtp->ignore_user_qs && !rdtp->in_user) { > rdtp->in_user = true; > rcu_eqs_enter(1); > } > diff --git a/kernel/rcutree.h b/kernel/rcutree.h > index 0dd5fd6..c190582 100644 > --- a/kernel/rcutree.h > +++ b/kernel/rcutree.h > @@ -103,6 +103,7 @@ struct rcu_dynticks { > int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ > #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ > #ifdef CONFIG_RCU_USER_QS > + bool ignore_user_qs; /* Treat userspace as extended QS or not */ > bool in_user; /* Is the CPU in userland from RCU POV? */ > #endif > }; > -- > 1.7.8 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
