If we are interrupting userspace, we don't need to keep the tick for RCU: quiescent states don't need to be reported because we soon run in userspace and local callbacks are handled by the nocb threads.
CHECKME: Do the nocb threads actually handle the global grace period completion for local callbacks? Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Alessio Igor Bogani <[email protected]> Cc: Andrew Morton <[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: Ingo Molnar <[email protected]> Cc: Li Zhong <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Paul Gortmaker <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Thomas Gleixner <[email protected]> --- kernel/time/tick-sched.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 1cd93a9..ecba8b7 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -22,6 +22,7 @@ #include <linux/module.h> #include <linux/irq_work.h> #include <linux/posix-timers.h> +#include <linux/context_tracking.h> #include <asm/irq_regs.h> @@ -604,10 +605,9 @@ static bool can_stop_full_tick(int cpu) /* * Keep the tick if we are asked to report a quiescent state. - * This must be further optimized (avoid checks for local callbacks, - * ignore RCU in userspace, etc... + * This must be further optimized (avoid checks for local callbacks) */ - if (rcu_pending(cpu)) { + if (!context_tracking_in_user() && rcu_pending(cpu)) { trace_printk("Can't stop: RCU pending\n"); return false; } -- 1.7.5.4 -- 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/
