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authorLinus Torvalds <torvalds@linux-foundation.org>2015-08-31 21:04:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-31 21:04:24 -0700
commit65a99597f044c083983f4274ab049c9ec3b9d764 (patch)
treef9c4271cf03b7d4ab71930915f00ef24139619d1 /kernel
parent418c2e1f67658460533e4aaa7a0bcc64290ec951 (diff)
parent555ee95a0a5a525ad2f1654fab0bd157de832b4f (diff)
downloadlinux-65a99597f044c083983f4274ab049c9ec3b9d764.tar.bz2
Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull NOHZ updates from Ingo Molnar: "The main changes, mostly written by Frederic Weisbecker, include: - Fix some jiffies based cputime assumptions. (No real harm because the concerned code isn't used by full dynticks.) - Simplify jiffies <-> usecs conversions. Remove dead code. - Remove early hacks on nohz full code that avoided messing up idle nohz internals. Now nohz integrates well full and idle and such hack have become needless. - Restart nohz full tick from irq exit. (A simplification and a preparation for future optimization on scheduler kick to nohz full) - Code cleanups. - Tile driver isolation enhancement on top of nohz. (Chris Metcalf)" * 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: nohz: Remove useless argument on tick_nohz_task_switch() nohz: Move tick_nohz_restart_sched_tick() above its users nohz: Restart nohz full tick from irq exit nohz: Remove idle task special case nohz: Prevent tilegx network driver interrupts alpha: Fix jiffies based cputime assumption apm32: Fix cputime == jiffies assumption jiffies: Remove HZ > USEC_PER_SEC special case
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c2
-rw-r--r--kernel/time/tick-sched.c72
-rw-r--r--kernel/time/time.c10
3 files changed, 35 insertions, 49 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7819725e9da8..8b864ecee0e1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2543,7 +2543,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
put_task_struct(prev);
}
- tick_nohz_task_switch(current);
+ tick_nohz_task_switch();
return rq;
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index c792429e98c6..3319e16f31e5 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -197,27 +197,9 @@ static bool can_stop_full_tick(void)
return true;
}
-static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now);
-
-/*
- * Re-evaluate the need for the tick on the current CPU
- * and restart it if necessary.
- */
-void __tick_nohz_full_check(void)
-{
- struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
-
- if (tick_nohz_full_cpu(smp_processor_id())) {
- if (ts->tick_stopped && !is_idle_task(current)) {
- if (!can_stop_full_tick())
- tick_nohz_restart_sched_tick(ts, ktime_get());
- }
- }
-}
-
static void nohz_full_kick_work_func(struct irq_work *work)
{
- __tick_nohz_full_check();
+ /* Empty, the tick restart happens on tick_nohz_irq_exit() */
}
static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {
@@ -252,7 +234,7 @@ void tick_nohz_full_kick_cpu(int cpu)
static void nohz_full_kick_ipi(void *info)
{
- __tick_nohz_full_check();
+ /* Empty, the tick restart happens on tick_nohz_irq_exit() */
}
/*
@@ -276,7 +258,7 @@ void tick_nohz_full_kick_all(void)
* It might need the tick due to per task/process properties:
* perf events, posix cpu timers, ...
*/
-void __tick_nohz_task_switch(struct task_struct *tsk)
+void __tick_nohz_task_switch(void)
{
unsigned long flags;
@@ -705,21 +687,38 @@ out:
return tick;
}
-static void tick_nohz_full_stop_tick(struct tick_sched *ts)
+static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
+{
+ /* Update jiffies first */
+ tick_do_update_jiffies64(now);
+ update_cpu_load_nohz();
+
+ calc_load_exit_idle();
+ touch_softlockup_watchdog();
+ /*
+ * Cancel the scheduled timer and restore the tick
+ */
+ ts->tick_stopped = 0;
+ ts->idle_exittime = now;
+
+ tick_nohz_restart(ts, now);
+}
+
+static void tick_nohz_full_update_tick(struct tick_sched *ts)
{
#ifdef CONFIG_NO_HZ_FULL
int cpu = smp_processor_id();
- if (!tick_nohz_full_cpu(cpu) || is_idle_task(current))
+ if (!tick_nohz_full_cpu(cpu))
return;
if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE)
return;
- if (!can_stop_full_tick())
- return;
-
- tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
+ if (can_stop_full_tick())
+ tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
+ else if (ts->tick_stopped)
+ tick_nohz_restart_sched_tick(ts, ktime_get());
#endif
}
@@ -849,7 +848,7 @@ void tick_nohz_irq_exit(void)
if (ts->inidle)
__tick_nohz_idle_enter(ts);
else
- tick_nohz_full_stop_tick(ts);
+ tick_nohz_full_update_tick(ts);
}
/**
@@ -864,23 +863,6 @@ ktime_t tick_nohz_get_sleep_length(void)
return ts->sleep_length;
}
-static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
-{
- /* Update jiffies first */
- tick_do_update_jiffies64(now);
- update_cpu_load_nohz();
-
- calc_load_exit_idle();
- touch_softlockup_watchdog();
- /*
- * Cancel the scheduled timer and restore the tick
- */
- ts->tick_stopped = 0;
- ts->idle_exittime = now;
-
- tick_nohz_restart(ts, now);
-}
-
static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
{
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 85d5bb1d67eb..ad1bf23e6eb7 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -268,10 +268,14 @@ EXPORT_SYMBOL(jiffies_to_msecs);
unsigned int jiffies_to_usecs(const unsigned long j)
{
-#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
+ /*
+ * Hz usually doesn't go much further MSEC_PER_SEC.
+ * jiffies_to_usecs() and usecs_to_jiffies() depend on that.
+ */
+ BUILD_BUG_ON(HZ > USEC_PER_SEC);
+
+#if !(USEC_PER_SEC % HZ)
return (USEC_PER_SEC / HZ) * j;
-#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
- return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
#else
# if BITS_PER_LONG == 32
return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;