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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2012-07-11 20:26:32 +0200 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2012-09-26 15:47:01 +0200 |
| commit | 1e1a689f10a27a4fe1ab9b4c6db04fa7232746a5 (patch) | |
| tree | 098f180287723813d248f59f452ca3a7db04b636 /kernel/rcutree.c | |
| parent | c5d900bf676b1e2a61c44483932c8088651bbb4e (diff) | |
| download | lwn-1e1a689f10a27a4fe1ab9b4c6db04fa7232746a5.tar.gz lwn-1e1a689f10a27a4fe1ab9b4c6db04fa7232746a5.zip | |
rcu: Ignore userspace extended quiescent state by default
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>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index d62c04482228..6b82a9565149 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -206,6 +206,9 @@ 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. */ @@ -430,7 +433,7 @@ 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); } |