hrtimer: Get rid of the resolution field in hrtimer_clock_base

The field has no value because all clock bases have the same
resolution. The resolution only changes when we switch to high
resolution timer mode. We can evaluate that from a single static
variable as well. In the !HIGHRES case its simply a constant.

Export the variable, so we can simplify the usage sites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.645454122@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 7770676c387a66cec9a8a3d8333bfa6e1e56ffe8..bc6f91b5443badd775d8b25b8389b45f9f09abe6 100644 (file)
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -137,7 +137,6 @@ struct hrtimer_sleeper {
  *                     timer to a base on another cpu.
  * @clockid:           clock id for per_cpu support
  * @active:            red black tree root node for the active timers
- * @resolution:                the resolution of the clock, in nanoseconds
  * @get_time:          function to retrieve the current time of the clock
  * @softirq_time:      the time when running the hrtimer queue in the softirq
  * @offset:            offset of this clock to the monotonic base
@@ -147,7 +146,6 @@ struct hrtimer_clock_base {
        int                     index;
        clockid_t               clockid;
        struct timerqueue_head  active;
-       ktime_t                 resolution;
        ktime_t                 (*get_time)(void);
        ktime_t                 softirq_time;
        ktime_t                 offset;
@@ -295,11 +293,15 @@ extern void hrtimer_peek_ahead_timers(void);
 
 extern void clock_was_set_delayed(void);
 
+extern unsigned int hrtimer_resolution;
+
 #else
 
 # define MONOTONIC_RES_NSEC    LOW_RES_NSEC
 # define KTIME_MONOTONIC_RES   KTIME_LOW_RES
 
+#define hrtimer_resolution     LOW_RES_NSEC
+
 static inline void hrtimer_peek_ahead_timers(void) { }
 
 /*

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 9abd50b60e83e6457d2686aaf1178c53d8da29cc..965687a1fce60086935e79af41a5d7d20080c0e7 100644 (file)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -66,7 +66,6 @@
  */
 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
 {
-
        .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
        .clock_base =
        {
@@ -74,25 +73,21 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
                        .index = HRTIMER_BASE_MONOTONIC,
                        .clockid = CLOCK_MONOTONIC,
                        .get_time = &ktime_get,
-                       .resolution = KTIME_LOW_RES,
                },
                {
                        .index = HRTIMER_BASE_REALTIME,
                        .clockid = CLOCK_REALTIME,
                        .get_time = &ktime_get_real,
-                       .resolution = KTIME_LOW_RES,
                },
                {
                        .index = HRTIMER_BASE_BOOTTIME,
                        .clockid = CLOCK_BOOTTIME,
                        .get_time = &ktime_get_boottime,
-                       .resolution = KTIME_LOW_RES,
                },
                {
                        .index = HRTIMER_BASE_TAI,
                        .clockid = CLOCK_TAI,
                        .get_time = &ktime_get_clocktai,
-                       .resolution = KTIME_LOW_RES,
                },
        }
 };
@@ -478,6 +473,8 @@ static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
  * High resolution timer enabled ?
  */
 static int hrtimer_hres_enabled __read_mostly  = 1;
+unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
+EXPORT_SYMBOL_GPL(hrtimer_resolution);
 
 /*
  * Enable / Disable high resolution mode
@@ -660,7 +657,7 @@ static void retrigger_next_event(void *arg)
  */
 static int hrtimer_switch_to_hres(void)
 {
-       int i, cpu = smp_processor_id();
+       int cpu = smp_processor_id();
        struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
        unsigned long flags;
 
@@ -676,8 +673,7 @@ static int hrtimer_switch_to_hres(void)
                return 0;
        }
        base->hres_active = 1;
-       for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
-               base->clock_base[i].resolution = KTIME_HIGH_RES;
+       hrtimer_resolution = HIGH_RES_NSEC;
 
        tick_setup_sched_timer();
        /* "Retrigger" the interrupt to get things going */
@@ -820,8 +816,8 @@ u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
        if (delta.tv64 < 0)
                return 0;
 
-       if (interval.tv64 < timer->base->resolution.tv64)
-               interval.tv64 = timer->base->resolution.tv64;
+       if (interval.tv64 < hrtimer_resolution)
+               interval.tv64 = hrtimer_resolution;
 
        if (unlikely(delta.tv64 >= interval.tv64)) {
                s64 incr = ktime_to_ns(interval);
@@ -963,7 +959,7 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
                 * timeouts. This will go away with the GTOD framework.
                 */
 #ifdef CONFIG_TIME_LOW_RES
-               tim = ktime_add_safe(tim, base->resolution);
+               tim = ktime_add_safe(tim, ktime_set(0, hrtimer_resolution));
 #endif
        }
 
@@ -1193,12 +1189,8 @@ EXPORT_SYMBOL_GPL(hrtimer_init);
  */
 int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
 {
-       struct hrtimer_cpu_base *cpu_base;
-       int base = hrtimer_clockid_to_base(which_clock);
-
-       cpu_base = raw_cpu_ptr(&hrtimer_bases);
-       *tp = ktime_to_timespec(cpu_base->clock_base[base].resolution);
-
+       tp->tv_sec = 0;
+       tp->tv_nsec = hrtimer_resolution;
        return 0;
 }
 EXPORT_SYMBOL_GPL(hrtimer_get_res);

diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 5960af2196acca6839c1271293e4c6186695b208..bdd5e987f1154319512eb6506049726a33aa905f 100644 (file)
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -127,10 +127,10 @@ static void
 print_base(struct seq_file *m, struct hrtimer_clock_base *base, u64 now)
 {
        SEQ_printf(m, "  .base:       %pK\n", base);
-       SEQ_printf(m, "  .index:      %d\n",
-                       base->index);
-       SEQ_printf(m, "  .resolution: %Lu nsecs\n",
-                       (unsigned long long)ktime_to_ns(base->resolution));
+       SEQ_printf(m, "  .index:      %d\n", base->index);
+
+       SEQ_printf(m, "  .resolution: %u nsecs\n", (unsigned) hrtimer_resolution);
+
        SEQ_printf(m,   "  .get_time:   ");
        print_name_offset(m, base->get_time);
        SEQ_printf(m,   "\n");