| Message ID | 1346360743-3628-6-git-send-email-paulmck@linux.vnet.ibm.com |
|---|---|
| State | Accepted |
| Commit | 1e1a689f10a27a4fe1ab9b4c6db04fa7232746a5 |
| Headers | show |
On Thu, Aug 30, 2012 at 02:05:23PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <fweisbec@gmail.com> > > 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 <fweisbec@gmail.com> > Cc: Alessio Igor Bogani <abogani@kernel.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Avi Kivity <avi@redhat.com> > Cc: Chris Metcalf <cmetcalf@tilera.com> > Cc: Christoph Lameter <cl@linux.com> > Cc: Geoff Levand <geoff@infradead.org> > Cc: Gilad Ben Yossef <gilad@benyossef.com> > Cc: Hakan Akkan <hakanakkan@gmail.com> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Josh Triplett <josh@joshtriplett.org> > Cc: Kevin Hilman <khilman@ti.com> > Cc: Max Krasnyansky <maxk@qualcomm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Stephen Hemminger <shemminger@vyatta.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> > 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 >
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 };