timers/nohz: Restructure and reshuffle struct tick_sched

Restructure and group fields by access in order to optimize cache
layout. While at it, also add missing kernel doc for two fields:
@last_jiffies and @idle_expires.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230222144649.624380-2-frederic@kernel.org

diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
index 5046495..c666325 100644 (file)
--- a/kernel/time/tick-sched.h
+++ b/kernel/time/tick-sched.h
@@ -22,65 +22,81 @@ enum tick_nohz_mode {
 
 /**
  * struct tick_sched - sched tick emulation and no idle tick control/stats
- * @sched_timer:       hrtimer to schedule the periodic tick in high
- *                     resolution mode
- * @check_clocks:      Notification mechanism about clocksource changes
- * @nohz_mode:         Mode - one state of tick_nohz_mode
+ *
  * @inidle:            Indicator that the CPU is in the tick idle mode
  * @tick_stopped:      Indicator that the idle tick has been stopped
  * @idle_active:       Indicator that the CPU is actively in the tick idle mode;
  *                     it is reset during irq handling phases.
- * @do_timer_lst:      CPU was the last one doing do_timer before going idle
+ * @do_timer_last:     CPU was the last one doing do_timer before going idle
  * @got_idle_tick:     Tick timer function has run with @inidle set
+ * @stalled_jiffies:   Number of stalled jiffies detected across ticks
+ * @last_tick_jiffies: Value of jiffies seen on last tick
+ * @sched_timer:       hrtimer to schedule the periodic tick in high
+ *                     resolution mode
  * @last_tick:         Store the last tick expiry time when the tick
  *                     timer is modified for nohz sleeps. This is necessary
  *                     to resume the tick timer operation in the timeline
  *                     when the CPU returns from nohz sleep.
  * @next_tick:         Next tick to be fired when in dynticks mode.
  * @idle_jiffies:      jiffies at the entry to idle for idle time accounting
+ * @idle_waketime:     Time when the idle was interrupted
+ * @idle_entrytime:    Time when the idle call was entered
+ * @nohz_mode:         Mode - one state of tick_nohz_mode
+ * @last_jiffies:      Base jiffies snapshot when next event was last computed
+ * @timer_expires_base:        Base time clock monotonic for @timer_expires
+ * @timer_expires:     Anticipated timer expiration time (in case sched tick is stopped)
+ * @next_timer:                Expiry time of next expiring timer for debugging purpose only
+ * @idle_expires:      Next tick in idle, for debugging purpose only
  * @idle_calls:                Total number of idle calls
  * @idle_sleeps:       Number of idle calls, where the sched tick was stopped
- * @idle_entrytime:    Time when the idle call was entered
- * @idle_waketime:     Time when the idle was interrupted
  * @idle_exittime:     Time when the idle state was left
  * @idle_sleeptime:    Sum of the time slept in idle with sched tick stopped
  * @iowait_sleeptime:  Sum of the time slept in idle with sched tick stopped, with IO outstanding
- * @timer_expires:     Anticipated timer expiration time (in case sched tick is stopped)
- * @timer_expires_base:        Base time clock monotonic for @timer_expires
- * @next_timer:                Expiry time of next expiring timer for debugging purpose only
  * @tick_dep_mask:     Tick dependency mask - is set, if someone needs the tick
- * @last_tick_jiffies: Value of jiffies seen on last tick
- * @stalled_jiffies:   Number of stalled jiffies detected across ticks
+ * @check_clocks:      Notification mechanism about clocksource changes
  */
 struct tick_sched {
-       struct hrtimer                  sched_timer;
-       unsigned long                   check_clocks;
-       enum tick_nohz_mode             nohz_mode;
-
+       /* Common flags */
        unsigned int                    inidle          : 1;
        unsigned int                    tick_stopped    : 1;
        unsigned int                    idle_active     : 1;
        unsigned int                    do_timer_last   : 1;
        unsigned int                    got_idle_tick   : 1;
 
+       /* Tick handling: jiffies stall check */
+       unsigned int                    stalled_jiffies;
+       unsigned long                   last_tick_jiffies;
+
+       /* Tick handling */
+       struct hrtimer                  sched_timer;
        ktime_t                         last_tick;
        ktime_t                         next_tick;
        unsigned long                   idle_jiffies;
-       unsigned long                   idle_calls;
-       unsigned long                   idle_sleeps;
-       ktime_t                         idle_entrytime;
        ktime_t                         idle_waketime;
-       ktime_t                         idle_exittime;
-       ktime_t                         idle_sleeptime;
-       ktime_t                         iowait_sleeptime;
+
+       /* Idle entry */
+       ktime_t                         idle_entrytime;
+
+       /* Tick stop */
+       enum tick_nohz_mode             nohz_mode;
        unsigned long                   last_jiffies;
-       u64                             timer_expires;
        u64                             timer_expires_base;
+       u64                             timer_expires;
        u64                             next_timer;
        ktime_t                         idle_expires;
+       unsigned long                   idle_calls;
+       unsigned long                   idle_sleeps;
+
+       /* Idle exit */
+       ktime_t                         idle_exittime;
+       ktime_t                         idle_sleeptime;
+       ktime_t                         iowait_sleeptime;
+
+       /* Full dynticks handling */
        atomic_t                        tick_dep_mask;
-       unsigned long                   last_tick_jiffies;
-       unsigned int                    stalled_jiffies;
+
+       /* Clocksource changes */
+       unsigned long                   check_clocks;
 };
 
 extern struct tick_sched *tick_get_tick_sched(int cpu);