linux-kernel - [PATCH v3 1/2] cputime: remove duplicate code in account_process

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Date:   Mon, 22 Jul 2019 15:38:39 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Alex Shi <alex.shi@...ux.alibaba.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Wanpeng Li <wanpeng.li@...mail.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/2] cputime: remove duplicate code in account_process_tick

The irqtime_account_process_tick path was introduced for precise ns irq
time account from commit abb74cefa9c6 ("sched: Export ns irqtimes
through /proc/stat") while account_process_tick still use jiffes. This
divide isn't necessary especially now both paths are ns precison.

Move out the irqtime_account_process_tick func from IRQ_TIME_ACCOUNTING.
So it do generally same things as account_process_tick whenever if
IRQ_TIME_ACCOUNTING set or if sched_clock_irqtime enabled.

Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
---
 kernel/sched/cputime.c | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 2305ce89a26c..5086b24d7bee 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -332,7 +332,6 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 	rcu_read_unlock();
 }
 
-#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 /*
  * Account a tick to a process and cpustat
  * @p: the process that the CPU time gets accounted to
@@ -390,6 +389,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 	}
 }
 
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 static void irqtime_account_idle_ticks(int ticks)
 {
 	struct rq *rq = this_rq();
@@ -398,8 +398,6 @@ static void irqtime_account_idle_ticks(int ticks)
 }
 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
 static inline void irqtime_account_idle_ticks(int ticks) { }
-static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
-						struct rq *rq, int nr_ticks) { }
 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 
 /*
@@ -474,31 +472,12 @@ void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
  */
 void account_process_tick(struct task_struct *p, int user_tick)
 {
-	u64 cputime, steal;
 	struct rq *rq = this_rq();
 
 	if (vtime_accounting_cpu_enabled())
 		return;
 
-	if (sched_clock_irqtime) {
-		irqtime_account_process_tick(p, user_tick, rq, 1);
-		return;
-	}
-
-	cputime = TICK_NSEC;
-	steal = steal_account_process_time(ULONG_MAX);
-
-	if (steal >= cputime)
-		return;
-
-	cputime -= steal;
-
-	if (user_tick)
-		account_user_time(p, cputime);
-	else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
-		account_system_time(p, HARDIRQ_OFFSET, cputime);
-	else
-		account_idle_time(cputime);
+	irqtime_account_process_tick(p, user_tick, rq, 1);
 }
 
 /*
-- 
2.19.1.856.g8858448bb