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Date: Fri, 2 Sep 2016 16:03:04 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Wanpeng Li <wanpeng.li@...mail.com>,
Eric Dumazet <eric.dumazet@...il.com>,
Ingo Molnar <mingo@...nel.org>, Mike Galbraith <efault@....de>,
Rik van Riel <riel@...hat.com>
Subject: [PATCH 4/5] irqtime: Consolidate accounting synchronization with u64_stats API
The irqtime accounting currently implement its own ad hoc implementation
of u64_stats API. Lets rather consolidate it with the appropriate
library.
Cc: Rik van Riel <riel@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
kernel/sched/cputime.c | 31 +++++++++++++---------------
kernel/sched/sched.h | 55 +++++++++++++++-----------------------------------
2 files changed, 30 insertions(+), 56 deletions(-)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index d4d12a9..f51c9a9 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -23,10 +23,8 @@
* 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 irqtime, cpu_irqtime);
-static DEFINE_PER_CPU(u64, irq_start_time);
static int sched_clock_irqtime;
void enable_sched_clock_irqtime(void)
@@ -39,16 +37,13 @@ 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.
*/
void irqtime_account_irq(struct task_struct *curr)
{
+ struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
s64 delta;
int cpu;
@@ -56,10 +51,10 @@ void irqtime_account_irq(struct task_struct *curr)
return;
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) - irqtime->irq_start_time;
+ irqtime->irq_start_time += delta;
- irq_time_write_begin();
+ u64_stats_update_begin(&irqtime->sync);
/*
* We do not account for softirq time from ksoftirqd here.
* We want to continue accounting softirq time to ksoftirqd thread
@@ -67,11 +62,11 @@ 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);
+ irqtime->hardirq_time += delta;
else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
- __this_cpu_add(cpu_softirq_time, delta);
+ irqtime->softirq_time += delta;
- irq_time_write_end();
+ u64_stats_update_end(&irqtime->sync);
}
EXPORT_SYMBOL_GPL(irqtime_account_irq);
@@ -79,9 +74,10 @@ static cputime_t irqtime_account_hi_update(cputime_t maxtime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
cputime_t irq_cputime;
+ u64 nsecs;
- irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
- cpustat[CPUTIME_IRQ];
+ nsecs = __this_cpu_read(cpu_irqtime.hardirq_time);
+ irq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_IRQ];
irq_cputime = min(irq_cputime, maxtime);
cpustat[CPUTIME_IRQ] += irq_cputime;
@@ -92,9 +88,10 @@ static cputime_t irqtime_account_si_update(cputime_t maxtime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
cputime_t softirq_cputime;
+ u64 nsecs;
- softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
- cpustat[CPUTIME_SOFTIRQ];
+ nsecs = __this_cpu_read(cpu_irqtime.softirq_time);
+ softirq_cputime = nsecs_to_cputime64(nsecs) - cpustat[CPUTIME_SOFTIRQ];
softirq_cputime = min(softirq_cputime, maxtime);
cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 420c05d..daf9193 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2,6 +2,7 @@
#include <linux/sched.h>
#include <linux/sched/sysctl.h>
#include <linux/sched/rt.h>
+#include <linux/u64_stats_sync.h>
#include <linux/sched/deadline.h>
#include <linux/binfmts.h>
#include <linux/mutex.h>
@@ -1711,52 +1712,28 @@ static inline void nohz_balance_exit_idle(unsigned int cpu) { }
#endif
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
-
-DECLARE_PER_CPU(u64, cpu_hardirq_time);
-DECLARE_PER_CPU(u64, cpu_softirq_time);
-
-#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);
-}
+struct irqtime {
+ u64 hardirq_time;
+ u64 softirq_time;
+ u64 irq_start_time;
+ struct u64_stats_sync sync;
+};
+
+DECLARE_PER_CPU(struct irqtime, cpu_irqtime);
static inline u64 irq_time_read(int cpu)
{
- u64 irq_time;
- unsigned seq;
+ struct irqtime *irqtime = &per_cpu(cpu_irqtime, cpu);
+ unsigned int seq;
+ u64 total;
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(&irqtime->sync);
+ total = irqtime->softirq_time + irqtime->hardirq_time;
+ } while (__u64_stats_fetch_retry(&irqtime->sync, seq));
- return irq_time;
+ return total;
}
-#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 */
#ifdef CONFIG_CPU_FREQ
--
2.7.0
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