path: root/debian/patches-rt/0003-sched-vtime-Consolidate-IRQ-time-accounting.patch

From: Frederic Weisbecker <frederic@kernel.org>
Date: Wed, 2 Dec 2020 12:57:30 +0100
Subject: [PATCH 3/5] sched/vtime: Consolidate IRQ time accounting
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.21-rt34.tar.xz

The 3 architectures implementing CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
all have their own version of irq time accounting that dispatch the
cputime to the appropriate index: hardirq, softirq, system, idle,
guest... from an all-in-one function.

Instead of having these ad-hoc versions, move the cputime destination
dispatch decision to the core code and leave only the actual per-index
cputime accounting to the architecture.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201202115732.27827-4-frederic@kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 arch/ia64/kernel/time.c    |   20 ++++++++++++----
 arch/powerpc/kernel/time.c |   56 ++++++++++++++++++++++++++++++++-------------
 arch/s390/kernel/vtime.c   |   45 +++++++++++++++++++++++++-----------
 include/linux/vtime.h      |   16 ++++--------
 kernel/sched/cputime.c     |   13 +++++++---
 5 files changed, 102 insertions(+), 48 deletions(-)

--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -138,12 +138,8 @@ void vtime_account_kernel(struct task_st
 	struct thread_info *ti = task_thread_info(tsk);
 	__u64 stime = vtime_delta(tsk);
 
-	if ((tsk->flags & PF_VCPU) && !irq_count())
+	if (tsk->flags & PF_VCPU)
 		ti->gtime += stime;
-	else if (hardirq_count())
-		ti->hardirq_time += stime;
-	else if (in_serving_softirq())
-		ti->softirq_time += stime;
 	else
 		ti->stime += stime;
 }
@@ -156,6 +152,20 @@ void vtime_account_idle(struct task_stru
 	ti->idle_time += vtime_delta(tsk);
 }
 
+void vtime_account_softirq(struct task_struct *tsk)
+{
+	struct thread_info *ti = task_thread_info(tsk);
+
+	ti->softirq_time += vtime_delta(tsk);
+}
+
+void vtime_account_hardirq(struct task_struct *tsk)
+{
+	struct thread_info *ti = task_thread_info(tsk);
+
+	ti->hardirq_time += vtime_delta(tsk);
+}
+
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
 static irqreturn_t
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -312,12 +312,11 @@ static unsigned long vtime_delta_scaled(
 	return stime_scaled;
 }
 
-static unsigned long vtime_delta(struct task_struct *tsk,
+static unsigned long vtime_delta(struct cpu_accounting_data *acct,
 				 unsigned long *stime_scaled,
 				 unsigned long *steal_time)
 {
 	unsigned long now, stime;
-	struct cpu_accounting_data *acct = get_accounting(tsk);
 
 	WARN_ON_ONCE(!irqs_disabled());
 
@@ -332,29 +331,30 @@ static unsigned long vtime_delta(struct
 	return stime;
 }
 
+static void vtime_delta_kernel(struct cpu_accounting_data *acct,
+			       unsigned long *stime, unsigned long *stime_scaled)
+{
+	unsigned long steal_time;
+
+	*stime = vtime_delta(acct, stime_scaled, &steal_time);
+	*stime -= min(*stime, steal_time);
+	acct->steal_time += steal_time;
+}
+
 void vtime_account_kernel(struct task_struct *tsk)
 {
-	unsigned long stime, stime_scaled, steal_time;
 	struct cpu_accounting_data *acct = get_accounting(tsk);
+	unsigned long stime, stime_scaled;
 
-	stime = vtime_delta(tsk, &stime_scaled, &steal_time);
-
-	stime -= min(stime, steal_time);
-	acct->steal_time += steal_time;
+	vtime_delta_kernel(acct, &stime, &stime_scaled);
 
-	if ((tsk->flags & PF_VCPU) && !irq_count()) {
+	if (tsk->flags & PF_VCPU) {
 		acct->gtime += stime;
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
 		acct->utime_scaled += stime_scaled;
 #endif
 	} else {
-		if (hardirq_count())
-			acct->hardirq_time += stime;
-		else if (in_serving_softirq())
-			acct->softirq_time += stime;
-		else
-			acct->stime += stime;
-
+		acct->stime += stime;
 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
 		acct->stime_scaled += stime_scaled;
 #endif
@@ -367,10 +367,34 @@ void vtime_account_idle(struct task_stru
 	unsigned long stime, stime_scaled, steal_time;
 	struct cpu_accounting_data *acct = get_accounting(tsk);
 
-	stime = vtime_delta(tsk, &stime_scaled, &steal_time);
+	stime = vtime_delta(acct, &stime_scaled, &steal_time);
 	acct->idle_time += stime + steal_time;
 }
 
+static void vtime_account_irq_field(struct cpu_accounting_data *acct,
+				    unsigned long *field)
+{
+	unsigned long stime, stime_scaled;
+
+	vtime_delta_kernel(acct, &stime, &stime_scaled);
+	*field += stime;
+#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
+	acct->stime_scaled += stime_scaled;
+#endif
+}
+
+void vtime_account_softirq(struct task_struct *tsk)
+{
+	struct cpu_accounting_data *acct = get_accounting(tsk);
+	vtime_account_irq_field(acct, &acct->softirq_time);
+}
+
+void vtime_account_hardirq(struct task_struct *tsk)
+{
+	struct cpu_accounting_data *acct = get_accounting(tsk);
+	vtime_account_irq_field(acct, &acct->hardirq_time);
+}
+
 static void vtime_flush_scaled(struct task_struct *tsk,
 			       struct cpu_accounting_data *acct)
 {
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -223,31 +223,50 @@ void vtime_flush(struct task_struct *tsk
 	S390_lowcore.avg_steal_timer = avg_steal;
 }
 
+static u64 vtime_delta(void)
+{
+	u64 timer = S390_lowcore.last_update_timer;
+
+	S390_lowcore.last_update_timer = get_vtimer();
+
+	return timer - S390_lowcore.last_update_timer;
+}
+
 /*
  * Update process times based on virtual cpu times stored by entry.S
  * to the lowcore fields user_timer, system_timer & steal_clock.
  */
 void vtime_account_kernel(struct task_struct *tsk)
 {
-	u64 timer;
-
-	timer = S390_lowcore.last_update_timer;
-	S390_lowcore.last_update_timer = get_vtimer();
-	timer -= S390_lowcore.last_update_timer;
+	u64 delta = vtime_delta();
 
-	if ((tsk->flags & PF_VCPU) && (irq_count() == 0))
-		S390_lowcore.guest_timer += timer;
-	else if (hardirq_count())
-		S390_lowcore.hardirq_timer += timer;
-	else if (in_serving_softirq())
-		S390_lowcore.softirq_timer += timer;
+	if (tsk->flags & PF_VCPU)
+		S390_lowcore.guest_timer += delta;
 	else
-		S390_lowcore.system_timer += timer;
+		S390_lowcore.system_timer += delta;
 
-	virt_timer_forward(timer);
+	virt_timer_forward(delta);
 }
 EXPORT_SYMBOL_GPL(vtime_account_kernel);
 
+void vtime_account_softirq(struct task_struct *tsk)
+{
+	u64 delta = vtime_delta();
+
+	S390_lowcore.softirq_timer += delta;
+
+	virt_timer_forward(delta);
+}
+
+void vtime_account_hardirq(struct task_struct *tsk)
+{
+	u64 delta = vtime_delta();
+
+	S390_lowcore.hardirq_timer += delta;
+
+	virt_timer_forward(delta);
+}
+
 /*
  * Sorted add to a list. List is linear searched until first bigger
  * element is found.
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -83,16 +83,12 @@ static inline void vtime_init_idle(struc
 #endif
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-extern void vtime_account_irq_enter(struct task_struct *tsk);
-static inline void vtime_account_irq_exit(struct task_struct *tsk)
-{
-	/* On hard|softirq exit we always account to hard|softirq cputime */
-	vtime_account_kernel(tsk);
-}
+extern void vtime_account_irq(struct task_struct *tsk);
+extern void vtime_account_softirq(struct task_struct *tsk);
+extern void vtime_account_hardirq(struct task_struct *tsk);
 extern void vtime_flush(struct task_struct *tsk);
 #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
-static inline void vtime_account_irq_enter(struct task_struct *tsk) { }
-static inline void vtime_account_irq_exit(struct task_struct *tsk) { }
+static inline void vtime_account_irq(struct task_struct *tsk) { }
 static inline void vtime_flush(struct task_struct *tsk) { }
 #endif
 
@@ -105,13 +101,13 @@ static inline void irqtime_account_irq(s
 
 static inline void account_irq_enter_time(struct task_struct *tsk)
 {
-	vtime_account_irq_enter(tsk);
+	vtime_account_irq(tsk);
 	irqtime_account_irq(tsk);
 }
 
 static inline void account_irq_exit_time(struct task_struct *tsk)
 {
-	vtime_account_irq_exit(tsk);
+	vtime_account_irq(tsk);
 	irqtime_account_irq(tsk);
 }
 
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -417,13 +417,18 @@ void vtime_task_switch(struct task_struc
 }
 # endif
 
-void vtime_account_irq_enter(struct task_struct *tsk)
+void vtime_account_irq(struct task_struct *tsk)
 {
-	if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
-	    !in_interrupt() && is_idle_task(tsk))
+	if (hardirq_count()) {
+		vtime_account_hardirq(tsk);
+	} else if (in_serving_softirq()) {
+		vtime_account_softirq(tsk);
+	} else if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
+		   is_idle_task(tsk)) {
 		vtime_account_idle(tsk);
-	else
+	} else {
 		vtime_account_kernel(tsk);
+	}
 }
 
 void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,