Merge branch 'timers/nohz-for-tip' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/nohz

Pull NOHZ updates from Frederic Weisbecker:

  - 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.

  - Simple code cleanups.

  - Tile driver isolation enhancement on top of nohz.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

8 files changed, 62 insertions, 75 deletions

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 36dc91ace83a..6cc08166ff00 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -1138,6 +1138,7 @@ SYSCALL_DEFINE2(osf_getrusage, int, who, struct rusage32 __user *, ru)
 {
         struct rusage32 r;
         cputime_t utime, stime;
+        unsigned long utime_jiffies, stime_jiffies;
 
         if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
                 return -EINVAL;
@@ -1146,14 +1147,18 @@ SYSCALL_DEFINE2(osf_getrusage, int, who, struct rusage32 __user *, ru)
         switch (who) {
         case RUSAGE_SELF:
                 task_cputime(current, &utime, &stime);
-                jiffies_to_timeval32(utime, &r.ru_utime);
-                jiffies_to_timeval32(stime, &r.ru_stime);
+                utime_jiffies = cputime_to_jiffies(utime);
+                stime_jiffies = cputime_to_jiffies(stime);
+                jiffies_to_timeval32(utime_jiffies, &r.ru_utime);
+                jiffies_to_timeval32(stime_jiffies, &r.ru_stime);
                 r.ru_minflt = current->min_flt;
                 r.ru_majflt = current->maj_flt;
                 break;
         case RUSAGE_CHILDREN:
-                jiffies_to_timeval32(current->signal->cutime, &r.ru_utime);
-                jiffies_to_timeval32(current->signal->cstime, &r.ru_stime);
+                utime_jiffies = cputime_to_jiffies(current->signal->cutime);
+                stime_jiffies = cputime_to_jiffies(current->signal->cstime);
+                jiffies_to_timeval32(utime_jiffies, &r.ru_utime);
+                jiffies_to_timeval32(stime_jiffies, &r.ru_stime);
                 r.ru_minflt = current->signal->cmin_flt;
                 r.ru_majflt = current->signal->cmaj_flt;
                 break;
diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 927ec9235947..052c9c3026cc 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -919,7 +919,7 @@ recalc:
         } else if (jiffies_since_last_check > idle_period) {
                 unsigned int idle_percentage;
 
-                idle_percentage = stime - last_stime;
+                idle_percentage = cputime_to_jiffies(stime - last_stime);
                 idle_percentage *= 100;
                 idle_percentage /= jiffies_since_last_check;
                 use_apm_idle = (idle_percentage > idle_threshold);
diff --git a/drivers/net/ethernet/tile/tilegx.c b/drivers/net/ethernet/tile/tilegx.c
index a3f7610002aa..0a15acc075b3 100644
--- a/drivers/net/ethernet/tile/tilegx.c
+++ b/drivers/net/ethernet/tile/tilegx.c
@@ -40,6 +40,7 @@
 #include <linux/tcp.h>
 #include <linux/net_tstamp.h>
 #include <linux/ptp_clock_kernel.h>
+#include <linux/tick.h>
 
 #include <asm/checksum.h>
 #include <asm/homecache.h>
@@ -2273,7 +2274,8 @@ static int __init tile_net_init_module(void)
                 tile_net_dev_init(name, mac);
 
         if (!network_cpus_init())
-                network_cpus_map = *cpu_online_mask;
+                cpumask_and(&network_cpus_map, housekeeping_cpumask(),
+                            cpu_online_mask);
 
         return 0;
 }
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index 535fd3bb1ba8..7c6febede6ba 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -363,18 +363,11 @@ static inline unsigned long msecs_to_jiffies(const unsigned int m)
 }
 
 extern unsigned long __usecs_to_jiffies(const unsigned int u);
-#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
+#if !(USEC_PER_SEC % HZ)
 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
 {
         return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
 }
-#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
-static inline unsigned long _usecs_to_jiffies(const unsigned int u)
-{
-        return u * (HZ / USEC_PER_SEC);
-}
-static inline unsigned long _usecs_to_jiffies(const unsigned int u)
-{
 #else
 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
 {
diff --git a/include/linux/tick.h b/include/linux/tick.h
index edbfc9a5293e..48d901f83f92 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -147,22 +147,29 @@ static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask)
                 cpumask_or(mask, mask, tick_nohz_full_mask);
 }
 
-extern void __tick_nohz_full_check(void);
 extern void tick_nohz_full_kick(void);
 extern void tick_nohz_full_kick_cpu(int cpu);
 extern void tick_nohz_full_kick_all(void);
-extern void __tick_nohz_task_switch(struct task_struct *tsk);
+extern void __tick_nohz_task_switch(void);
 #else
 static inline bool tick_nohz_full_enabled(void) { return false; }
 static inline bool tick_nohz_full_cpu(int cpu) { return false; }
 static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) { }
-static inline void __tick_nohz_full_check(void) { }
 static inline void tick_nohz_full_kick_cpu(int cpu) { }
 static inline void tick_nohz_full_kick(void) { }
 static inline void tick_nohz_full_kick_all(void) { }
-static inline void __tick_nohz_task_switch(struct task_struct *tsk) { }
+static inline void __tick_nohz_task_switch(void) { }
 #endif
 
+static inline const struct cpumask *housekeeping_cpumask(void)
+{
+#ifdef CONFIG_NO_HZ_FULL
+        if (tick_nohz_full_enabled())
+                return housekeeping_mask;
+#endif
+        return cpu_possible_mask;
+}
+
 static inline bool is_housekeeping_cpu(int cpu)
 {
 #ifdef CONFIG_NO_HZ_FULL
@@ -181,16 +188,10 @@ static inline void housekeeping_affine(struct task_struct *t)
 #endif
 }
 
-static inline void tick_nohz_full_check(void)
-{
-        if (tick_nohz_full_enabled())
-                __tick_nohz_full_check();
-}
-
-static inline void tick_nohz_task_switch(struct task_struct *tsk)
+static inline void tick_nohz_task_switch(void)
 {
         if (tick_nohz_full_enabled())
-                __tick_nohz_task_switch(tsk);
+                __tick_nohz_task_switch();
 }
 
 #endif
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 78b4bad10081..4d34035bb3ee 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2489,7 +2489,7 @@ 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;