Commit-ID: 22ab8bc02a5f6e8ffc418759894f7a6b0b632331 Gitweb: https://git.kernel.org/tip/22ab8bc02a5f6e8ffc418759894f7a6b0b632331 Author: Frederic Weisbecker <frede...@kernel.org> AuthorDate: Wed, 21 Feb 2018 05:17:25 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 21 Feb 2018 09:49:08 +0100
nohz: Allow to check if remote CPU tick is stopped This check is racy but provides a good heuristic to determine whether a CPU may need a remote tick or not. Signed-off-by: Frederic Weisbecker <frede...@kernel.org> Reviewed-by: Thomas Gleixner <t...@linutronix.de> Acked-by: Peter Zijlstra <pet...@infradead.org> Cc: Chris Metcalf <cmetc...@mellanox.com> Cc: Christoph Lameter <c...@linux.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Luiz Capitulino <lcapitul...@redhat.com> Cc: Mike Galbraith <efa...@gmx.de> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Rik van Riel <r...@redhat.com> Cc: Wanpeng Li <kernel...@gmail.com> Link: http://lkml.kernel.org/r/1519186649-3242-4-git-send-email-frede...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- include/linux/tick.h | 2 ++ kernel/time/tick-sched.c | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 86576d9..7f8c9a1 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -114,6 +114,7 @@ enum tick_dep_bits { #ifdef CONFIG_NO_HZ_COMMON extern bool tick_nohz_enabled; extern bool tick_nohz_tick_stopped(void); +extern bool tick_nohz_tick_stopped_cpu(int cpu); extern void tick_nohz_idle_enter(void); extern void tick_nohz_idle_exit(void); extern void tick_nohz_irq_exit(void); @@ -125,6 +126,7 @@ extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); #else /* !CONFIG_NO_HZ_COMMON */ #define tick_nohz_enabled (0) static inline int tick_nohz_tick_stopped(void) { return 0; } +static inline int tick_nohz_tick_stopped_cpu(int cpu) { return 0; } static inline void tick_nohz_idle_enter(void) { } static inline void tick_nohz_idle_exit(void) { } diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 0aba041..d479b21 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -486,6 +486,13 @@ bool tick_nohz_tick_stopped(void) return __this_cpu_read(tick_cpu_sched.tick_stopped); } +bool tick_nohz_tick_stopped_cpu(int cpu) +{ + struct tick_sched *ts = per_cpu_ptr(&tick_cpu_sched, cpu); + + return ts->tick_stopped; +} + /** * tick_nohz_update_jiffies - update jiffies when idle was interrupted *
