[PATCH 0/5] sched/cputime: irqtime cleanups v2

[PATCH 0/5] sched/cputime: irqtime cleanups v2

[Frederic Weisbecker]

This second version fixes the ifdeffery issues reported by Paolo Bonzini
and includes Rick's reviewed-by tags.

I also intended to include Peterz's patch for lockdep assertion on irqs
disabled but unfortunately I get false positives as irqs_disabled()
doesn't always imply !current->hardirqs_enabled. This seems to happen
during the boot with IRQs interrupting lockdep internals while
current->lockdep_recursion == 1. Therefore the trace_hardirqs_off() on
x86 IRQ entry gets ignored. I'll investigate further and try to get
that fixed in order to introduce lockdep_assert_irqs_disabled() properly
but that's outside the scope of this patchset now.

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
	sched/irqtime-v2

HEAD: e336b2491bf02e95ff3387e7d7a8276b22c8b5f3

Thanks,
	Frederic
---

Frederic Weisbecker (5):
      irqtime: No need for preempt-safe accessors
      irqtime: Remove needless IRQs disablement on kcpustat update
      u64_stats: Introduce IRQs disabled helpers
      irqtime: Consolidate accounting synchronization with u64_stats API
      irqtime: Consolidate irqtime flushing code


 include/linux/u64_stats_sync.h | 45 +++++++++++++++++++----------------
 kernel/sched/cputime.c         | 54 ++++++++++++++++++------------------------
 kernel/sched/sched.h           | 53 ++++++++++++-----------------------------
 3 files changed, 62 insertions(+), 90 deletions(-)

[PATCH 1/5] irqtime: No need for preempt-safe accessors

[Frederic Weisbecker]

We can safely use the preempt-unsafe accessors for irqtime when we
flush its counters to kcpustat as IRQs are disabled at this time.

Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/sched/cputime.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index b93c72d..f111076 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -82,7 +82,7 @@ static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 	cputime_t irq_cputime;
 
 	local_irq_save(flags);
-	irq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_hardirq_time)) -
+	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
 		      cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
@@ -97,7 +97,7 @@ static cputime_t irqtime_account_si_update(cputime_t maxtime)
 	cputime_t softirq_cputime;
 
 	local_irq_save(flags);
-	softirq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_softirq_time)) -
+	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
 			  cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
-- 
2.7.4

[tip:sched/core] sched/irqtime: No need for preempt-safe accessors

[tip-bot for Frederic Weisbecker]

Commit-ID:  f9094a65755df86ec931f47b781f68ea3095cb56
Gitweb:     http://git.kernel.org/tip/f9094a65755df86ec931f47b781f68ea3095cb56
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Mon, 26 Sep 2016 02:29:17 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 30 Sep 2016 11:46:38 +0200

sched/irqtime: No need for preempt-safe accessors

We can safely use the preempt-unsafe accessors for irqtime when we
flush its counters to kcpustat as IRQs are disabled at this time.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/cputime.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index b93c72d..f111076 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -82,7 +82,7 @@ static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 	cputime_t irq_cputime;
 
 	local_irq_save(flags);
-	irq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_hardirq_time)) -
+	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
 		      cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
@@ -97,7 +97,7 @@ static cputime_t irqtime_account_si_update(cputime_t maxtime)
 	cputime_t softirq_cputime;
 
 	local_irq_save(flags);
-	softirq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_softirq_time)) -
+	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
 			  cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;

[PATCH 2/5] irqtime: Remove needless IRQs disablement on kcpustat update

[Frederic Weisbecker]

The callers of the functions performing irqtime kcpustat updates have
IRQS disabled, no need to disable them again.

Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/sched/cputime.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index f111076..94b1a72 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -78,30 +78,26 @@ EXPORT_SYMBOL_GPL(irqtime_account_irq);
 static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	unsigned long flags;
 	cputime_t irq_cputime;
 
-	local_irq_save(flags);
 	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
 		      cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
-	local_irq_restore(flags);
+
 	return irq_cputime;
 }
 
 static cputime_t irqtime_account_si_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	unsigned long flags;
 	cputime_t softirq_cputime;
 
-	local_irq_save(flags);
 	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
 			  cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
-	local_irq_restore(flags);
+
 	return softirq_cputime;
 }
 
@@ -295,6 +291,9 @@ static inline cputime_t account_other_time(cputime_t max)
 {
 	cputime_t accounted;
 
+	/* Shall be converted to a lockdep-enabled lightweight check */
+	WARN_ON_ONCE(!irqs_disabled());
+
 	accounted = steal_account_process_time(max);
 
 	if (accounted < max)
-- 
2.7.4

[tip:sched/core] sched/irqtime: Remove needless IRQs disablement on kcpustat update

[tip-bot for Frederic Weisbecker]

Commit-ID:  2810f611f908112ea1b30bc016d25205acb3d486
Gitweb:     http://git.kernel.org/tip/2810f611f908112ea1b30bc016d25205acb3d486
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Mon, 26 Sep 2016 02:29:18 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 30 Sep 2016 11:46:39 +0200

sched/irqtime: Remove needless IRQs disablement on kcpustat update

The callers of the functions performing irqtime kcpustat updates have
IRQS disabled, no need to disable them again.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/cputime.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index f111076..94b1a72 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -78,30 +78,26 @@ EXPORT_SYMBOL_GPL(irqtime_account_irq);
 static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	unsigned long flags;
 	cputime_t irq_cputime;
 
-	local_irq_save(flags);
 	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
 		      cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
-	local_irq_restore(flags);
+
 	return irq_cputime;
 }
 
 static cputime_t irqtime_account_si_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	unsigned long flags;
 	cputime_t softirq_cputime;
 
-	local_irq_save(flags);
 	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
 			  cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
-	local_irq_restore(flags);
+
 	return softirq_cputime;
 }
 
@@ -295,6 +291,9 @@ static inline cputime_t account_other_time(cputime_t max)
 {
 	cputime_t accounted;
 
+	/* Shall be converted to a lockdep-enabled lightweight check */
+	WARN_ON_ONCE(!irqs_disabled());
+
 	accounted = steal_account_process_time(max);
 
 	if (accounted < max)

[PATCH 3/5] u64_stats: Introduce IRQs disabled helpers

[Frederic Weisbecker]

Introduce light versions of u64_stats helpers for context where
either preempt or IRQs are disabled. This way we can make this library
usable by scheduler irqtime accounting which currenty implement its
ad-hoc version.

Cc: Rik van Riel <riel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 include/linux/u64_stats_sync.h | 51 ++++++++++++++++++++++--------------------
 1 file changed, 27 insertions(+), 24 deletions(-)

diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h
index d3a2bb7..650f3dd 100644
--- a/include/linux/u64_stats_sync.h
+++ b/include/linux/u64_stats_sync.h
@@ -103,29 +103,40 @@ static inline void u64_stats_update_end_raw(struct u64_stats_sync *syncp)
 #endif
 }
 
+static inline unsigned int __u64_stats_fetch_begin(const struct u64_stats_sync *syncp)
+{
+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
+	return read_seqcount_begin(&syncp->seq);
+#else
+	return 0;
+#endif
+}
+
 static inline unsigned int u64_stats_fetch_begin(const struct u64_stats_sync *syncp)
 {
-#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
-	return read_seqcount_begin(&syncp->seq);
-#else
-#if BITS_PER_LONG==32
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
 	preempt_disable();
 #endif
-	return 0;
+	return __u64_stats_fetch_begin(syncp);
+}
+
+static inline bool __u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
+					 unsigned int start)
+{
+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
+	return read_seqcount_retry(&syncp->seq, start);
+#else
+	return false;
 #endif
 }
 
 static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
 					 unsigned int start)
 {
-#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
-	return read_seqcount_retry(&syncp->seq, start);
-#else
-#if BITS_PER_LONG==32
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
 	preempt_enable();
 #endif
-	return false;
-#endif
+	return __u64_stats_fetch_retry(syncp, start);
 }
 
 /*
@@ -136,27 +147,19 @@ static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
  */
 static inline unsigned int u64_stats_fetch_begin_irq(const struct u64_stats_sync *syncp)
 {
-#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
-	return read_seqcount_begin(&syncp->seq);
-#else
-#if BITS_PER_LONG==32
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
 	local_irq_disable();
 #endif
-	return 0;
-#endif
+	return __u64_stats_fetch_begin(syncp);
 }
 
 static inline bool u64_stats_fetch_retry_irq(const struct u64_stats_sync *syncp,
-					 unsigned int start)
+					     unsigned int start)
 {
-#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
-	return read_seqcount_retry(&syncp->seq, start);
-#else
-#if BITS_PER_LONG==32
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
 	local_irq_enable();
 #endif
-	return false;
-#endif
+	return __u64_stats_fetch_retry(syncp, start);
 }
 
 #endif /* _LINUX_U64_STATS_SYNC_H */
-- 
2.7.4

[tip:sched/core] u64_stats: Introduce IRQs disabled helpers

[tip-bot for Frederic Weisbecker]

Commit-ID:  68107df5f2cb5dc3785be40162bfe2f19a178bbb
Gitweb:     http://git.kernel.org/tip/68107df5f2cb5dc3785be40162bfe2f19a178bbb
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Mon, 26 Sep 2016 02:29:19 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 30 Sep 2016 11:46:40 +0200

u64_stats: Introduce IRQs disabled helpers

Introduce light versions of u64_stats helpers for context where
either preempt or IRQs are disabled. This way we can make this library
usable by scheduler irqtime accounting which currenty implement its
ad-hoc version.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/u64_stats_sync.h | 45 ++++++++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h
index d3a2bb7..650f3dd 100644
--- a/include/linux/u64_stats_sync.h
+++ b/include/linux/u64_stats_sync.h
@@ -103,31 +103,42 @@ static inline void u64_stats_update_end_raw(struct u64_stats_sync *syncp)
 #endif
 }
 
-static inline unsigned int u64_stats_fetch_begin(const struct u64_stats_sync *syncp)
+static inline unsigned int __u64_stats_fetch_begin(const struct u64_stats_sync *syncp)
 {
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
 	return read_seqcount_begin(&syncp->seq);
 #else
-#if BITS_PER_LONG==32
-	preempt_disable();
-#endif
 	return 0;
 #endif
 }
 
-static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
+static inline unsigned int u64_stats_fetch_begin(const struct u64_stats_sync *syncp)
+{
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
+	preempt_disable();
+#endif
+	return __u64_stats_fetch_begin(syncp);
+}
+
+static inline bool __u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
 					 unsigned int start)
 {
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
 	return read_seqcount_retry(&syncp->seq, start);
 #else
-#if BITS_PER_LONG==32
-	preempt_enable();
-#endif
 	return false;
 #endif
 }
 
+static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
+					 unsigned int start)
+{
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
+	preempt_enable();
+#endif
+	return __u64_stats_fetch_retry(syncp, start);
+}
+
 /*
  * In case irq handlers can update u64 counters, readers can use following helpers
  * - SMP 32bit arches use seqcount protection, irq safe.
@@ -136,27 +147,19 @@ static inline bool u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
  */
 static inline unsigned int u64_stats_fetch_begin_irq(const struct u64_stats_sync *syncp)
 {
-#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
-	return read_seqcount_begin(&syncp->seq);
-#else
-#if BITS_PER_LONG==32
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
 	local_irq_disable();
 #endif
-	return 0;
-#endif
+	return __u64_stats_fetch_begin(syncp);
 }
 
 static inline bool u64_stats_fetch_retry_irq(const struct u64_stats_sync *syncp,
-					 unsigned int start)
+					     unsigned int start)
 {
-#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
-	return read_seqcount_retry(&syncp->seq, start);
-#else
-#if BITS_PER_LONG==32
+#if BITS_PER_LONG==32 && !defined(CONFIG_SMP)
 	local_irq_enable();
 #endif
-	return false;
-#endif
+	return __u64_stats_fetch_retry(syncp, start);
 }
 
 #endif /* _LINUX_U64_STATS_SYNC_H */

[PATCH 4/5] irqtime: Consolidate accounting synchronization with u64_stats API

[Frederic Weisbecker]

The irqtime accounting currently implement its own ad hoc implementation
of u64_stats API. Lets rather consolidate it with the appropriate
library.

Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/sched/cputime.c | 31 +++++++++++++---------------
 kernel/sched/sched.h   | 55 +++++++++++++++-----------------------------------
 2 files changed, 30 insertions(+), 56 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 94b1a72..1cea2f1 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -23,10 +23,8 @@
  * task when irq is in progress while we read rq->clock. That is a worthy
  * compromise in place of having locks on each irq in account_system_time.
  */
-DEFINE_PER_CPU(u64, cpu_hardirq_time);
-DEFINE_PER_CPU(u64, cpu_softirq_time);
+DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
 
-static DEFINE_PER_CPU(u64, irq_start_time);
 static int sched_clock_irqtime;
 
 void enable_sched_clock_irqtime(void)
@@ -39,16 +37,13 @@ void disable_sched_clock_irqtime(void)
 	sched_clock_irqtime = 0;
 }
 
-#ifndef CONFIG_64BIT
-DEFINE_PER_CPU(seqcount_t, irq_time_seq);
-#endif /* CONFIG_64BIT */
-
 /*
  * Called before incrementing preempt_count on {soft,}irq_enter
  * and before decrementing preempt_count on {soft,}irq_exit.
  */
 void irqtime_account_irq(struct task_struct *curr)
 {
+	struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
 	s64 delta;
 	int cpu;
 
@@ -56,10 +51,10 @@ void irqtime_account_irq(struct task_struct *curr)
 		return;
 
 	cpu = smp_processor_id();
-	delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
-	__this_cpu_add(irq_start_time, delta);
+	delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
+	irqtime->irq_start_time += delta;
 
-	irq_time_write_begin();
+	u64_stats_update_begin(&irqtime->sync);
 	/*
 	 * We do not account for softirq time from ksoftirqd here.
 	 * We want to continue accounting softirq time to ksoftirqd thread
@@ -67,11 +62,11 @@ void irqtime_account_irq(struct task_struct *curr)
 	 * that do not consume any time, but still wants to run.
 	 */
 	if (hardirq_count())
-		__this_cpu_add(cpu_hardirq_time, delta);
+		irqtime->hardirq_time += delta;
 	else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
-		__this_cpu_add(cpu_softirq_time, delta);
+		irqtime->softirq_time += delta;
 
-	irq_time_write_end();
+	u64_stats_update_end(&irqtime->sync);
 }
 EXPORT_SYMBOL_GPL(irqtime_account_irq);
 
@@ -79,9 +74,10 @@ static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 	cputime_t irq_cputime;
+	u64 nsecs;
 
-	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
-		      cpustat[CPUTIME_IRQ];
+	nsecs = __this_cpu_read(cpu_irqtime.hardirq_time);
+	irq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
 
@@ -92,9 +88,10 @@ static cputime_t irqtime_account_si_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 	cputime_t softirq_cputime;
+	u64 nsecs;
 
-	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
-			  cpustat[CPUTIME_SOFTIRQ];
+	nsecs = __this_cpu_read(cpu_irqtime.softirq_time);
+	softirq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 420c05d..daf9193 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2,6 +2,7 @@
 #include <linux/sched.h>
 #include <linux/sched/sysctl.h>
 #include <linux/sched/rt.h>
+#include <linux/u64_stats_sync.h>
 #include <linux/sched/deadline.h>
 #include <linux/binfmts.h>
 #include <linux/mutex.h>
@@ -1711,52 +1712,28 @@ static inline void nohz_balance_exit_idle(unsigned int cpu) { }
 #endif
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
-
-DECLARE_PER_CPU(u64, cpu_hardirq_time);
-DECLARE_PER_CPU(u64, cpu_softirq_time);
-
-#ifndef CONFIG_64BIT
-DECLARE_PER_CPU(seqcount_t, irq_time_seq);
-
-static inline void irq_time_write_begin(void)
-{
-	__this_cpu_inc(irq_time_seq.sequence);
-	smp_wmb();
-}
-
-static inline void irq_time_write_end(void)
-{
-	smp_wmb();
-	__this_cpu_inc(irq_time_seq.sequence);
-}
+struct irqtime {
+	u64			hardirq_time;
+	u64			softirq_time;
+	u64			irq_start_time;
+	struct u64_stats_sync	sync;
+};
+
+DECLARE_PER_CPU(struct irqtime, cpu_irqtime);
 
 static inline u64 irq_time_read(int cpu)
 {
-	u64 irq_time;
-	unsigned seq;
+	struct irqtime *irqtime = &per_cpu(cpu_irqtime, cpu);
+	unsigned int seq;
+	u64 total;
 
 	do {
-		seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
-		irq_time = per_cpu(cpu_softirq_time, cpu) +
-			   per_cpu(cpu_hardirq_time, cpu);
-	} while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
+		seq = __u64_stats_fetch_begin(&irqtime->sync);
+		total = irqtime->softirq_time + irqtime->hardirq_time;
+	} while (__u64_stats_fetch_retry(&irqtime->sync, seq));
 
-	return irq_time;
+	return total;
 }
-#else /* CONFIG_64BIT */
-static inline void irq_time_write_begin(void)
-{
-}
-
-static inline void irq_time_write_end(void)
-{
-}
-
-static inline u64 irq_time_read(int cpu)
-{
-	return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
-}
-#endif /* CONFIG_64BIT */
 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 
 #ifdef CONFIG_CPU_FREQ
-- 
2.7.4

[tip:sched/core] sched/irqtime: Consolidate accounting synchronization with u64_stats API

[tip-bot for Frederic Weisbecker]

Commit-ID:  19d23dbfeb10724675152915e76e03d771f23d9d
Gitweb:     http://git.kernel.org/tip/19d23dbfeb10724675152915e76e03d771f23d9d
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Mon, 26 Sep 2016 02:29:20 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 30 Sep 2016 11:46:40 +0200

sched/irqtime: Consolidate accounting synchronization with u64_stats API

The irqtime accounting currently implement its own ad hoc implementation
of u64_stats API. Lets rather consolidate it with the appropriate
library.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/cputime.c | 31 +++++++++++++----------------
 kernel/sched/sched.h   | 53 ++++++++++++++------------------------------------
 2 files changed, 29 insertions(+), 55 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 94b1a72..1cea2f1 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -23,10 +23,8 @@
  * task when irq is in progress while we read rq->clock. That is a worthy
  * compromise in place of having locks on each irq in account_system_time.
  */
-DEFINE_PER_CPU(u64, cpu_hardirq_time);
-DEFINE_PER_CPU(u64, cpu_softirq_time);
+DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
 
-static DEFINE_PER_CPU(u64, irq_start_time);
 static int sched_clock_irqtime;
 
 void enable_sched_clock_irqtime(void)
@@ -39,16 +37,13 @@ void disable_sched_clock_irqtime(void)
 	sched_clock_irqtime = 0;
 }
 
-#ifndef CONFIG_64BIT
-DEFINE_PER_CPU(seqcount_t, irq_time_seq);
-#endif /* CONFIG_64BIT */
-
 /*
  * Called before incrementing preempt_count on {soft,}irq_enter
  * and before decrementing preempt_count on {soft,}irq_exit.
  */
 void irqtime_account_irq(struct task_struct *curr)
 {
+	struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
 	s64 delta;
 	int cpu;
 
@@ -56,10 +51,10 @@ void irqtime_account_irq(struct task_struct *curr)
 		return;
 
 	cpu = smp_processor_id();
-	delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
-	__this_cpu_add(irq_start_time, delta);
+	delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
+	irqtime->irq_start_time += delta;
 
-	irq_time_write_begin();
+	u64_stats_update_begin(&irqtime->sync);
 	/*
 	 * We do not account for softirq time from ksoftirqd here.
 	 * We want to continue accounting softirq time to ksoftirqd thread
@@ -67,11 +62,11 @@ void irqtime_account_irq(struct task_struct *curr)
 	 * that do not consume any time, but still wants to run.
 	 */
 	if (hardirq_count())
-		__this_cpu_add(cpu_hardirq_time, delta);
+		irqtime->hardirq_time += delta;
 	else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
-		__this_cpu_add(cpu_softirq_time, delta);
+		irqtime->softirq_time += delta;
 
-	irq_time_write_end();
+	u64_stats_update_end(&irqtime->sync);
 }
 EXPORT_SYMBOL_GPL(irqtime_account_irq);
 
@@ -79,9 +74,10 @@ static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 	cputime_t irq_cputime;
+	u64 nsecs;
 
-	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
-		      cpustat[CPUTIME_IRQ];
+	nsecs = __this_cpu_read(cpu_irqtime.hardirq_time);
+	irq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
 
@@ -92,9 +88,10 @@ static cputime_t irqtime_account_si_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 	cputime_t softirq_cputime;
+	u64 nsecs;
 
-	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
-			  cpustat[CPUTIME_SOFTIRQ];
+	nsecs = __this_cpu_read(cpu_irqtime.softirq_time);
+	softirq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5489d07..19b9986 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2,6 +2,7 @@
 #include <linux/sched.h>
 #include <linux/sched/sysctl.h>
 #include <linux/sched/rt.h>
+#include <linux/u64_stats_sync.h>
 #include <linux/sched/deadline.h>
 #include <linux/binfmts.h>
 #include <linux/mutex.h>
@@ -1735,52 +1736,28 @@ static inline void nohz_balance_exit_idle(unsigned int cpu) { }
 #endif
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
+struct irqtime {
+	u64			hardirq_time;
+	u64			softirq_time;
+	u64			irq_start_time;
+	struct u64_stats_sync	sync;
+};
 
-DECLARE_PER_CPU(u64, cpu_hardirq_time);
-DECLARE_PER_CPU(u64, cpu_softirq_time);
-
-#ifndef CONFIG_64BIT
-DECLARE_PER_CPU(seqcount_t, irq_time_seq);
-
-static inline void irq_time_write_begin(void)
-{
-	__this_cpu_inc(irq_time_seq.sequence);
-	smp_wmb();
-}
-
-static inline void irq_time_write_end(void)
-{
-	smp_wmb();
-	__this_cpu_inc(irq_time_seq.sequence);
-}
+DECLARE_PER_CPU(struct irqtime, cpu_irqtime);
 
 static inline u64 irq_time_read(int cpu)
 {
-	u64 irq_time;
-	unsigned seq;
+	struct irqtime *irqtime = &per_cpu(cpu_irqtime, cpu);
+	unsigned int seq;
+	u64 total;
 
 	do {
-		seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
-		irq_time = per_cpu(cpu_softirq_time, cpu) +
-			   per_cpu(cpu_hardirq_time, cpu);
-	} while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
-
-	return irq_time;
-}
-#else /* CONFIG_64BIT */
-static inline void irq_time_write_begin(void)
-{
-}
+		seq = __u64_stats_fetch_begin(&irqtime->sync);
+		total = irqtime->softirq_time + irqtime->hardirq_time;
+	} while (__u64_stats_fetch_retry(&irqtime->sync, seq));
 
-static inline void irq_time_write_end(void)
-{
-}
-
-static inline u64 irq_time_read(int cpu)
-{
-	return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
+	return total;
 }
-#endif /* CONFIG_64BIT */
 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 
 #ifdef CONFIG_CPU_FREQ

[PATCH 5/5] irqtime: Consolidate irqtime flushing code

[Frederic Weisbecker]

The code performing irqtime nsecs stats flushing to kcpustat is roughly
the same for hardirq and softirq. So lets consolidate that common code.

Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/sched/cputime.c | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 1cea2f1..5ebee31 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -70,32 +70,28 @@ void irqtime_account_irq(struct task_struct *curr)
 }
 EXPORT_SYMBOL_GPL(irqtime_account_irq);
 
-static cputime_t irqtime_account_hi_update(cputime_t maxtime)
+static cputime_t irqtime_account_update(u64 irqtime, int idx, cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 	cputime_t irq_cputime;
-	u64 nsecs;
 
-	nsecs = __this_cpu_read(cpu_irqtime.hardirq_time);
-	irq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_IRQ];
+	irq_cputime = nsecs_to_cputime64(irqtime) - cpustat[idx];
 	irq_cputime = min(irq_cputime, maxtime);
-	cpustat[CPUTIME_IRQ] += irq_cputime;
+	cpustat[idx] += irq_cputime;
 
 	return irq_cputime;
 }
 
+static cputime_t irqtime_account_hi_update(cputime_t maxtime)
+{
+	return irqtime_account_update(__this_cpu_read(cpu_irqtime.hardirq_time),
+				      CPUTIME_IRQ, maxtime);
+}
+
 static cputime_t irqtime_account_si_update(cputime_t maxtime)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	cputime_t softirq_cputime;
-	u64 nsecs;
-
-	nsecs = __this_cpu_read(cpu_irqtime.softirq_time);
-	softirq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_SOFTIRQ];
-	softirq_cputime = min(softirq_cputime, maxtime);
-	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
-
-	return softirq_cputime;
+	return irqtime_account_update(__this_cpu_read(cpu_irqtime.softirq_time),
+				      CPUTIME_SOFTIRQ, maxtime);
 }
 
 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
-- 
2.7.4

[tip:sched/core] sched/irqtime: Consolidate irqtime flushing code

[tip-bot for Frederic Weisbecker]

Commit-ID:  447976ef4fd09b1be88b316d1a81553f1aa7cd07
Gitweb:     http://git.kernel.org/tip/447976ef4fd09b1be88b316d1a81553f1aa7cd07
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Mon, 26 Sep 2016 02:29:21 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 30 Sep 2016 11:46:41 +0200

sched/irqtime: Consolidate irqtime flushing code

The code performing irqtime nsecs stats flushing to kcpustat is roughly
the same for hardirq and softirq. So lets consolidate that common code.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/cputime.c | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 1cea2f1..5ebee31 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -70,32 +70,28 @@ void irqtime_account_irq(struct task_struct *curr)
 }
 EXPORT_SYMBOL_GPL(irqtime_account_irq);
 
-static cputime_t irqtime_account_hi_update(cputime_t maxtime)
+static cputime_t irqtime_account_update(u64 irqtime, int idx, cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
 	cputime_t irq_cputime;
-	u64 nsecs;
 
-	nsecs = __this_cpu_read(cpu_irqtime.hardirq_time);
-	irq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_IRQ];
+	irq_cputime = nsecs_to_cputime64(irqtime) - cpustat[idx];
 	irq_cputime = min(irq_cputime, maxtime);
-	cpustat[CPUTIME_IRQ] += irq_cputime;
+	cpustat[idx] += irq_cputime;
 
 	return irq_cputime;
 }
 
-static cputime_t irqtime_account_si_update(cputime_t maxtime)
+static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	cputime_t softirq_cputime;
-	u64 nsecs;
-
-	nsecs = __this_cpu_read(cpu_irqtime.softirq_time);
-	softirq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_SOFTIRQ];
-	softirq_cputime = min(softirq_cputime, maxtime);
-	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
+	return irqtime_account_update(__this_cpu_read(cpu_irqtime.hardirq_time),
+				      CPUTIME_IRQ, maxtime);
+}
 
-	return softirq_cputime;
+static cputime_t irqtime_account_si_update(cputime_t maxtime)
+{
+	return irqtime_account_update(__this_cpu_read(cpu_irqtime.softirq_time),
+				      CPUTIME_SOFTIRQ, maxtime);
 }
 
 #else /* CONFIG_IRQ_TIME_ACCOUNTING */