Skip to contentSkip to conversation

NOHZ updates for v4.3

GIT PULL Ingo Molnar 1 participant 1 message Aug 31, 2015

Subsystems (7)
Network drivers x86 Scheduler Alpha port +3 more subsystems
lore
Share & tools
lore

Ingo Molnar

author maintainer
#0 lore raw

Linus,

Please pull the latest timers-nohz-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-nohz-for-linus

# HEAD: 555ee95a0a5a525ad2f1654fab0bd157de832b4f Merge branch 'timers/nohz-for-tip' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/nohz

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)

Thanks,

Ingo

------------------>
Chris Metcalf (1):
nohz: Prevent tilegx network driver interrupts

Frederic Weisbecker (7):
jiffies: Remove HZ > USEC_PER_SEC special case
apm32: Fix cputime == jiffies assumption
alpha: Fix jiffies based cputime assumption
nohz: Remove idle task special case
nohz: Restart nohz full tick from irq exit
nohz: Move tick_nohz_restart_sched_tick() above its users
nohz: Remove useless argument on tick_nohz_task_switch()

 arch/alpha/kernel/osf_sys.c        | 13 ++++---
 arch/x86/kernel/apm_32.c           |  2 +-
 drivers/net/ethernet/tile/tilegx.c |  4 ++-
 include/linux/jiffies.h            |  9 +----
 include/linux/tick.h               | 25 ++++++-------
 kernel/sched/core.c                |  2 +-
 kernel/time/tick-sched.c           | 72 ++++++++++++++------------------------
 kernel/time/time.c                 | 10 ++++--
 8 files changed, 62 insertions(+), 75 deletions(-)
arch/alpha/kernel/osf_sys.c +9 -4
index 36dc91ace83a..6cc08166ff00 100644
@@ -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;
arch/x86/kernel/apm_32.c +1 -1
index 927ec9235947..052c9c3026cc 100644
@@ -919,7 +919,7 @@ static int apm_cpu_idle(struct cpuidle_device *dev,
 	} 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);
drivers/net/ethernet/tile/tilegx.c +3 -1
index a3f7610002aa..0a15acc075b3 100644
@@ -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;
 }
include/linux/jiffies.h +1 -8
index 535fd3bb1ba8..7c6febede6ba 100644
@@ -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)
 {
include/linux/tick.h +13 -12
index edbfc9a5293e..48d901f83f92 100644
@@ -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
kernel/sched/core.c +1 -1
index 78b4bad10081..4d34035bb3ee 100644
@@ -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;
 }
kernel/time/tick-sched.c +27 -45

119 lines not on this page · raw message

kernel/time/time.c +7 -3
index 85d5bb1d67eb..ad1bf23e6eb7 100644
@@ -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;