linux-kernel - [PATCH 03/10] cputime: Allow accounting system time using cpustat index

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Date:   Tue,  6 Dec 2016 03:32:16 +0100
From:   Frederic Weisbecker <fweisbec@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <fweisbec@...il.com>,
        Tony Luck <tony.luck@...el.com>,
        Wanpeng Li <wanpeng.li@...mail.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Mackerras <paulus@...ba.org>,
        Ingo Molnar <mingo@...nel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Rik van Riel <riel@...hat.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Stanislaw Gruszka <sgruszka@...hat.com>
Subject: [PATCH 03/10] cputime: Allow accounting system time using cpustat index

In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE to delay
cputime accounting to the tick, let's provide APIs to account system
time to precise contexts: hardirq, softirq, pure system, ...

Inspired-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Stanislaw Gruszka <sgruszka@...hat.com>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 include/linux/kernel_stat.h |  4 ++++
 kernel/sched/cputime.c      | 19 ++++++++++++++-----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 00f7768..544aa86 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -80,10 +80,14 @@ static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
 
 extern void account_user_time(struct task_struct *, cputime_t);
 extern void account_system_time(struct task_struct *, int, cputime_t);
+extern void account_system_index_time(struct task_struct *, cputime_t,
+				      enum cpu_usage_stat);
 extern void account_steal_time(cputime_t);
 extern void account_idle_time(cputime_t);
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+extern void account_system_index_scaled(struct task_struct *, cputime_t,
+					cputime_t, enum cpu_usage_stat);
 static inline void account_process_tick(struct task_struct *tsk, int user)
 {
 	vtime_account_user(tsk);
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 7700a9c..0e6ea60 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -176,8 +176,8 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime)
  * @cputime: the cpu time spent in kernel space since the last update
  * @index: pointer to cpustat field that has to be updated
  */
-static inline
-void __account_system_time(struct task_struct *p, cputime_t cputime, int index)
+void account_system_index_time(struct task_struct *p,
+			       cputime_t cputime, enum cpu_usage_stat index)
 {
 	/* Add system time to process. */
 	p->stime += cputime;
@@ -190,6 +190,15 @@ void __account_system_time(struct task_struct *p, cputime_t cputime, int index)
 	acct_account_cputime(p);
 }
 
+#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
+void account_system_index_scaled(struct task_struct *p, cputime_t cputime,
+				 cputime_t scaled, enum cpu_usage_stat index)
+{
+	p->stimescaled += scaled;
+	account_system_index_time(p, cputime, index);
+}
+#endif
+
 /*
  * Account system cpu time to a process.
  * @p: the process that the cpu time gets accounted to
@@ -213,7 +222,7 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
 	else
 		index = CPUTIME_SYSTEM;
 
-	__account_system_time(p, cputime, index);
+	account_system_index_time(p, cputime, index);
 }
 
 /*
@@ -400,7 +409,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 		 * So, we have to handle it separately here.
 		 * Also, p->stime needs to be updated for ksoftirqd.
 		 */
-		__account_system_time(p, cputime, CPUTIME_SOFTIRQ);
+		account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
 	} else if (user_tick) {
 		account_user_time(p, cputime);
 	} else if (p == rq->idle) {
@@ -408,7 +417,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 	} else if (p->flags & PF_VCPU) { /* System time or guest time */
 		account_guest_time(p, cputime);
 	} else {
-		__account_system_time(p, cputime, CPUTIME_SYSTEM);
+		account_system_index_time(p, cputime, CPUTIME_SYSTEM);
 	}
 }
 
-- 
2.7.4