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Date: Fri, 28 Nov 2014 19:23:53 +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>,
Peter Zijlstra <peterz@...radead.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Thomas Gleixner <tglx@...utronix.de>,
Oleg Nesterov <oleg@...hat.com>,
Paul Mackerras <paulus@...ba.org>,
Wu Fengguang <fengguang.wu@...el.com>,
Ingo Molnar <mingo@...nel.org>, Rik van Riel <riel@...hat.com>,
Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: [RFC PATCH 23/30] cputime: Convert irq_time_accounting to use u64_stats_sync
Irqtime accounting internals uses open-coded u64_stats_sync. Lets
consolidate it with the relevant APIs.
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Wu Fengguang <fengguang.wu@...el.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
kernel/sched/cputime.c | 24 +++++++++---------------
kernel/sched/sched.h | 47 +++++++++++++----------------------------------
2 files changed, 22 insertions(+), 49 deletions(-)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index eefe1ec..f55633f 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -20,10 +20,8 @@
* task when irq is in progress while we read rq->clock. That is a worthy
* compromise in place of having locks on each irq in account_system_time.
*/
-DEFINE_PER_CPU(u64, cpu_hardirq_time);
-DEFINE_PER_CPU(u64, cpu_softirq_time);
+DEFINE_PER_CPU(struct cpu_irqtime, cpu_irqtime);
-static DEFINE_PER_CPU(u64, irq_start_time);
static int sched_clock_irqtime;
void enable_sched_clock_irqtime(void)
@@ -36,10 +34,6 @@ void disable_sched_clock_irqtime(void)
sched_clock_irqtime = 0;
}
-#ifndef CONFIG_64BIT
-DEFINE_PER_CPU(seqcount_t, irq_time_seq);
-#endif /* CONFIG_64BIT */
-
/*
* Called before incrementing preempt_count on {soft,}irq_enter
* and before decrementing preempt_count on {soft,}irq_exit.
@@ -56,10 +50,10 @@ void irqtime_account_irq(struct task_struct *curr)
local_irq_save(flags);
cpu = smp_processor_id();
- delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
- __this_cpu_add(irq_start_time, delta);
+ delta = sched_clock_cpu(cpu) - __this_cpu_read(cpu_irqtime.irq_start_time);
+ __this_cpu_add(cpu_irqtime.irq_start_time, delta);
- irq_time_write_begin();
+ u64_stats_update_begin(this_cpu_ptr(&cpu_irqtime.stats_sync));
/*
* We do not account for softirq time from ksoftirqd here.
* We want to continue accounting softirq time to ksoftirqd thread
@@ -67,11 +61,11 @@ void irqtime_account_irq(struct task_struct *curr)
* that do not consume any time, but still wants to run.
*/
if (hardirq_count())
- __this_cpu_add(cpu_hardirq_time, delta);
+ __this_cpu_add(cpu_irqtime.hardirq_time, delta);
else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
- __this_cpu_add(cpu_softirq_time, delta);
+ __this_cpu_add(cpu_irqtime.softirq_time, delta);
- irq_time_write_end();
+ u64_stats_update_end(this_cpu_ptr(&cpu_irqtime.stats_sync));
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(irqtime_account_irq);
@@ -84,7 +78,7 @@ static int irqtime_account_hi_update(u64 threshold)
int ret = 0;
local_irq_save(flags);
- latest_ns = this_cpu_read(cpu_hardirq_time);
+ latest_ns = this_cpu_read(cpu_irqtime.hardirq_time);
if (latest_ns - cpustat[CPUTIME_IRQ] > threshold)
ret = 1;
local_irq_restore(flags);
@@ -99,7 +93,7 @@ static int irqtime_account_si_update(u64 threshold)
int ret = 0;
local_irq_save(flags);
- latest_ns = this_cpu_read(cpu_softirq_time);
+ latest_ns = this_cpu_read(cpu_irqtime.softirq_time);
if (latest_ns - cpustat[CPUTIME_SOFTIRQ] > threshold)
ret = 1;
local_irq_restore(flags);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 24156c84..bb3e66f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -8,6 +8,7 @@
#include <linux/stop_machine.h>
#include <linux/tick.h>
#include <linux/slab.h>
+#include <linux/u64_stats_sync.h>
#include "cpupri.h"
#include "cpudeadline.h"
@@ -1521,49 +1522,27 @@ enum rq_nohz_flag_bits {
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
-DECLARE_PER_CPU(u64, cpu_hardirq_time);
-DECLARE_PER_CPU(u64, cpu_softirq_time);
+struct cpu_irqtime {
+ u64 hardirq_time;
+ u64 softirq_time;
+ u64 irq_start_time;
+ struct u64_stats_sync stats_sync;
+};
-#ifndef CONFIG_64BIT
-DECLARE_PER_CPU(seqcount_t, irq_time_seq);
-
-static inline void irq_time_write_begin(void)
-{
- __this_cpu_inc(irq_time_seq.sequence);
- smp_wmb();
-}
-
-static inline void irq_time_write_end(void)
-{
- smp_wmb();
- __this_cpu_inc(irq_time_seq.sequence);
-}
+DECLARE_PER_CPU(struct cpu_irqtime, cpu_irqtime);
+/* Must be called with preemption disabled */
static inline u64 irq_time_read(int cpu)
{
u64 irq_time;
unsigned seq;
do {
- seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
- irq_time = per_cpu(cpu_softirq_time, cpu) +
- per_cpu(cpu_hardirq_time, cpu);
- } while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
+ seq = __u64_stats_fetch_begin(&per_cpu(cpu_irqtime, cpu).stats_sync);
+ irq_time = per_cpu(cpu_irqtime.softirq_time, cpu) +
+ per_cpu(cpu_irqtime.hardirq_time, cpu);
+ } while (__u64_stats_fetch_retry(&per_cpu(cpu_irqtime, cpu).stats_sync, seq));
return irq_time;
}
-#else /* CONFIG_64BIT */
-static inline void irq_time_write_begin(void)
-{
-}
-
-static inline void irq_time_write_end(void)
-{
-}
-
-static inline u64 irq_time_read(int cpu)
-{
- return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
-}
-#endif /* CONFIG_64BIT */
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
--
2.1.3
--
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