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Date: Thu, 26 Jun 2014 18:17:03 +0900
From: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To: linux-kernel@...r.kernel.org
CC: Fernando Luis Vazquez Cao <fernando_b1@....ntt.co.jp>,
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
Frederic Weisbecker <fweisbec@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Arjan van de Ven <arjan@...ux.intel.com>,
Oleg Nesterov <oleg@...hat.com>,
Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
Denys Vlasenko <vda.linux@...glemail.com>
Subject: [PATCH 8/8] cputime: iowait aware idle tick accounting
By changes in vtime* codes by previous patches, now account_idle_time()
become a function to be called only from tick-accounting codes.
Introduce __account_idle_ticks() to do iowait accounting in ticks
properly. For this purpose record jiffies at end of iowait.
Not-Tested-by: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
---
include/linux/kernel_stat.h | 1 +
kernel/sched/core.c | 1 +
kernel/sched/cputime.c | 68 +++++++++++++++++++++++++++++-------------
kernel/sched/sched.h | 1 +
4 files changed, 50 insertions(+), 21 deletions(-)
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index ecbc52f..bdea2f7 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -85,6 +85,7 @@ extern unsigned long long task_delta_exec(struct task_struct *);
extern void account_user_time(struct task_struct *, cputime_t, cputime_t);
extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t);
extern void account_steal_time(cputime_t);
+extern void account_iowait_time(cputime_t);
extern void account_idle_time(cputime_t);
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f8eec61..5d3ebc3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4347,6 +4347,7 @@ static inline void iowait_stop(struct rq *rq)
if (!rq->nr_iowait && rq != this_rq()) {
vtime_iowait_exit(rq->cpu);
rq->last_iowait = ktime_get();
+ rq->last_iowait_jiffies = jiffies;
}
raw_spin_unlock(&rq->iowait_lock);
}
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 866a3ff..42a0e99 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -240,40 +240,65 @@ void account_steal_time(cputime_t cputime)
}
/*
+ * Account for iowait time.
+ * @cputime: the cpu time spent in io wait
+ */
+void account_iowait_time(cputime_t cputime)
+{
+ u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+ cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
+}
+
+/*
+ * Account for idle time.
+ * @cputime: the cpu time spent in idle wait
+ */
+void account_idle_time(cputime_t cputime)
+{
+ u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+ cpustat[CPUTIME_IDLE] += (__force u64) cputime;
+}
+
+/*
* Account for idle and iowait time in a dulation.
* @idle_enter: time stamp at idle entry
* @iowait_exit: time stamp when nr_iowait dropped to 0
* @idle_exit: time stamp at idle exit
*/
-void account_idle_and_iowait(cputime_t idle_enter, cputime_t iowait_exit, cputime_t idle_exit)
+void account_idle_and_iowait(cputime_t idle_enter, cputime_t iowait_exit,
+ cputime_t idle_exit)
{
- u64 *cpustat = kcpustat_this_cpu->cpustat;
struct rq *rq = this_rq();
if (rq->nr_iowait > 0 || iowait_exit > idle_exit) {
- cpustat[CPUTIME_IOWAIT] += (__force u64) idle_exit - idle_enter;
+ account_iowait_time(idle_exit - idle_enter);
} else if (iowait_exit > idle_enter) {
- cpustat[CPUTIME_IOWAIT] += (__force u64) iowait_exit - idle_enter;
- cpustat[CPUTIME_IDLE] += (__force u64) idle_exit - iowait_exit;
+ account_iowait_time(iowait_exit - idle_enter);
+ account_idle_time(idle_exit - iowait_exit);
} else {
- cpustat[CPUTIME_IDLE] += (__force u64) idle_exit - idle_enter;
+ account_idle_time(idle_exit - idle_enter);
}
}
/*
- * Account for idle time.
- * @cputime: the cpu time spent in idle wait (sometimes include iowait time)
+ * Account for idle and iowait time.
+ * @ticks: ticks spent in idle/io wait
*/
-void account_idle_time(cputime_t cputime)
+static void __account_idle_ticks(int ticks)
{
- u64 *cpustat = kcpustat_this_cpu->cpustat;
struct rq *rq = this_rq();
+ unsigned long no_io_ticks = jiffies - rq->last_iowait_jiffies;
- /* FIXME */
- if (rq->nr_iowait > 0)
- cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
- else
- cpustat[CPUTIME_IDLE] += (__force u64) cputime;
+ if (rq->nr_iowait > 0) {
+ account_iowait_time(jiffies_to_cputime(ticks));
+ } else if (no_io_ticks < ticks) {
+ account_iowait_time(jiffies_to_cputime(ticks - no_io_ticks));
+ account_idle_time(jiffies_to_cputime(no_io_ticks));
+ } else {
+ account_idle_time(jiffies_to_cputime(ticks));
+ }
}
static __always_inline bool steal_account_process_tick(void)
@@ -380,11 +405,11 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
} else if (user_tick) {
account_user_time(p, cputime, scaled);
} else if (p == rq->idle) {
- account_idle_time(cputime);
+ __account_idle_ticks(ticks);
} else if (p->flags & PF_VCPU) { /* System time or guest time */
account_guest_time(p, cputime, scaled);
} else {
- __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
+ __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
}
}
@@ -396,7 +421,8 @@ 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,
+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 */
@@ -499,7 +525,7 @@ void account_process_tick(struct task_struct *p, int user_tick)
account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
one_jiffy_scaled);
else
- account_idle_time(cputime_one_jiffy);
+ __account_idle_ticks(1);
}
/*
@@ -514,7 +540,7 @@ void account_steal_ticks(unsigned long ticks)
/*
* Account multiple ticks of idle time.
- * @ticks: number of stolen ticks
+ * @ticks: number of idle ticks
*/
void account_idle_ticks(unsigned long ticks)
{
@@ -524,7 +550,7 @@ void account_idle_ticks(unsigned long ticks)
return;
}
- account_idle_time(jiffies_to_cputime(ticks));
+ __account_idle_ticks(ticks);
}
/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4ddfddc..e5fb7b5 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -564,6 +564,7 @@ struct rq {
raw_spinlock_t iowait_lock ____cacheline_aligned;
unsigned int nr_iowait;
ktime_t last_iowait;
+ unsigned long last_iowait_jiffies;
#ifdef CONFIG_SMP
struct root_domain *rd;
--
1.7.1
--
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