linux-kernel - [PATCH 3/4] irqtime: add irq type parameter to irqtime_account

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Message-Id: <1467315350-3152-4-git-send-email-riel@redhat.com>
Date:	Thu, 30 Jun 2016 15:35:49 -0400
From:	riel@...hat.com
To:	linux-kernel@...r.kernel.org
Cc:	peterz@...radead.org, mingo@...nel.org, pbonzini@...hat.com,
	fweisbec@...hat.com, wanpeng.li@...mail.com, efault@....de,
	tglx@...utronix.de, rkrcmar@...hat.com
Subject: [PATCH 3/4] irqtime: add irq type parameter to irqtime_account_irq

From: Rik van Riel <riel@...hat.com>

Add an irq type parameter and documentation to irqtime_account_irq,
this can be used to distinguish between transitioning from process
context to hardirq time, and from process context to softirq time.

This is necessary to be able to remove the local_irq_disable from
irqtime_account_irq.

Signed-off-by: Rik van Riel <riel@...hat.com>
---
 include/linux/hardirq.h | 20 ++++++++++----------
 include/linux/vtime.h   | 12 ++++++------
 kernel/sched/cputime.c  |  9 ++++++++-
 kernel/softirq.c        |  6 +++---
 4 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index dfd59d6bc6f0..1ebb31f56285 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -32,11 +32,11 @@ extern void rcu_nmi_exit(void);
  * always balanced, so the interrupted value of ->hardirq_context
  * will always be restored.
  */
-#define __irq_enter()					\
-	do {						\
-		account_irq_enter_time(current);	\
-		preempt_count_add(HARDIRQ_OFFSET);	\
-		trace_hardirq_enter();			\
+#define __irq_enter()							\
+	do {								\
+		account_irq_enter_time(current, HARDIRQ_OFFSET);	\
+		preempt_count_add(HARDIRQ_OFFSET);			\
+		trace_hardirq_enter();					\
 	} while (0)
 
 /*
@@ -47,11 +47,11 @@ extern void irq_enter(void);
 /*
  * Exit irq context without processing softirqs:
  */
-#define __irq_exit()					\
-	do {						\
-		trace_hardirq_exit();			\
-		account_irq_exit_time(current);		\
-		preempt_count_sub(HARDIRQ_OFFSET);	\
+#define __irq_exit()							\
+	do {								\
+		trace_hardirq_exit();					\
+		account_irq_exit_time(current, HARDIRQ_OFFSET);		\
+		preempt_count_sub(HARDIRQ_OFFSET);			\
 	} while (0)
 
 /*
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index d1977d84ebdf..31e486d741b0 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -112,21 +112,21 @@ static inline void vtime_init_idle(struct task_struct *tsk, int cpu) { }
 #endif
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
-extern void irqtime_account_irq(struct task_struct *tsk);
+extern void irqtime_account_irq(struct task_struct *tsk, int irqtype);
 #else
-static inline void irqtime_account_irq(struct task_struct *tsk) { }
+static inline void irqtime_account_irq(struct task_struct *tsk, int irqtype) { }
 #endif
 
-static inline void account_irq_enter_time(struct task_struct *tsk)
+static inline void account_irq_enter_time(struct task_struct *tsk, int irqtype)
 {
 	vtime_account_irq_enter(tsk);
-	irqtime_account_irq(tsk);
+	irqtime_account_irq(tsk, irqtype);
 }
 
-static inline void account_irq_exit_time(struct task_struct *tsk)
+static inline void account_irq_exit_time(struct task_struct *tsk, int irqtype)
 {
 	vtime_account_irq_exit(tsk);
-	irqtime_account_irq(tsk);
+	irqtime_account_irq(tsk, irqtype);
 }
 
 #endif /* _LINUX_KERNEL_VTIME_H */
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index c4349f2cacf6..a0aefd4c7ea6 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -46,8 +46,15 @@ DEFINE_PER_CPU(seqcount_t, irq_time_seq);
 /*
  * Called before incrementing preempt_count on {soft,}irq_enter
  * and before decrementing preempt_count on {soft,}irq_exit.
+ *
+ * There are six possible transitions:
+ * process -> softirq, softirq -> process
+ * process -> hardirq, hardirq -> process
+ * softirq -> hardirq, hardirq -> softirq
+ *
+ * When exiting hardirq or softirq time, account the elapsed time.
  */
-void irqtime_account_irq(struct task_struct *curr)
+void irqtime_account_irq(struct task_struct *curr, int irqtype)
 {
 	unsigned long flags;
 	s64 delta;
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 17caf4b63342..a311c9622c86 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -245,7 +245,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 	current->flags &= ~PF_MEMALLOC;
 
 	pending = local_softirq_pending();
-	account_irq_enter_time(current);
+	account_irq_enter_time(current, SOFTIRQ_OFFSET);
 
 	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
 	in_hardirq = lockdep_softirq_start();
@@ -295,7 +295,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 	}
 
 	lockdep_softirq_end(in_hardirq);
-	account_irq_exit_time(current);
+	account_irq_exit_time(current, SOFTIRQ_OFFSET);
 	__local_bh_enable(SOFTIRQ_OFFSET);
 	WARN_ON_ONCE(in_interrupt());
 	tsk_restore_flags(current, old_flags, PF_MEMALLOC);
@@ -385,7 +385,7 @@ void irq_exit(void)
 	WARN_ON_ONCE(!irqs_disabled());
 #endif
 
-	account_irq_exit_time(current);
+	account_irq_exit_time(current, HARDIRQ_OFFSET);
 	preempt_count_sub(HARDIRQ_OFFSET);
 	if (!in_interrupt() && local_softirq_pending())
 		invoke_softirq();
-- 
2.7.4