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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-25 14:43:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-25 14:43:00 -0700
commit766fd5f6cdaf1d558afba19850493b2603c9625d (patch)
treefcb4eb4a041aa0b0f9309c30a982c5b7bdad76ae /kernel/sched
parentcca08cd66ce6cc37812b6b36986ba7eaabd33e0b (diff)
parent553bf6bbfd8a540c70aee28eb50e24caff456a03 (diff)
Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull NOHZ updates from Ingo Molnar: - fix system/idle cputime leaked on cputime accounting (all nohz configs) (Rik van Riel) - remove the messy, ad-hoc irqtime account on nohz-full and make it compatible with CONFIG_IRQ_TIME_ACCOUNTING=y instead (Rik van Riel) - cleanups (Frederic Weisbecker) - remove unecessary irq disablement in the irqtime code (Rik van Riel) * 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cputime: Drop local_irq_save/restore from irqtime_account_irq() sched/cputime: Reorganize vtime native irqtime accounting headers sched/cputime: Clean up the old vtime gen irqtime accounting completely sched/cputime: Replace VTIME_GEN irq time code with IRQ_TIME_ACCOUNTING code sched/cputime: Count actually elapsed irq & softirq time
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/cputime.c171
1 files changed, 87 insertions, 84 deletions
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 3d60e5d76fdb..ea0f6f31a244 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -49,15 +49,12 @@ DEFINE_PER_CPU(seqcount_t, irq_time_seq);
*/
void irqtime_account_irq(struct task_struct *curr)
{
- unsigned long flags;
s64 delta;
int cpu;
if (!sched_clock_irqtime)
return;
- 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);
@@ -75,44 +72,53 @@ void irqtime_account_irq(struct task_struct *curr)
__this_cpu_add(cpu_softirq_time, delta);
irq_time_write_end();
- local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(irqtime_account_irq);
-static int irqtime_account_hi_update(void)
+static cputime_t irqtime_account_hi_update(cputime_t maxtime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
unsigned long flags;
- u64 latest_ns;
- int ret = 0;
+ cputime_t irq_cputime;
local_irq_save(flags);
- latest_ns = this_cpu_read(cpu_hardirq_time);
- if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
- ret = 1;
+ irq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_hardirq_time)) -
+ cpustat[CPUTIME_IRQ];
+ irq_cputime = min(irq_cputime, maxtime);
+ cpustat[CPUTIME_IRQ] += irq_cputime;
local_irq_restore(flags);
- return ret;
+ return irq_cputime;
}
-static int irqtime_account_si_update(void)
+static cputime_t irqtime_account_si_update(cputime_t maxtime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
unsigned long flags;
- u64 latest_ns;
- int ret = 0;
+ cputime_t softirq_cputime;
local_irq_save(flags);
- latest_ns = this_cpu_read(cpu_softirq_time);
- if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
- ret = 1;
+ softirq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_softirq_time)) -
+ cpustat[CPUTIME_SOFTIRQ];
+ softirq_cputime = min(softirq_cputime, maxtime);
+ cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
local_irq_restore(flags);
- return ret;
+ return softirq_cputime;
}
#else /* CONFIG_IRQ_TIME_ACCOUNTING */
#define sched_clock_irqtime (0)
+static cputime_t irqtime_account_hi_update(cputime_t dummy)
+{
+ return 0;
+}
+
+static cputime_t irqtime_account_si_update(cputime_t dummy)
+{
+ return 0;
+}
+
#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
static inline void task_group_account_field(struct task_struct *p, int index,
@@ -257,32 +263,45 @@ void account_idle_time(cputime_t cputime)
cpustat[CPUTIME_IDLE] += (__force u64) cputime;
}
-static __always_inline unsigned long steal_account_process_tick(unsigned long max_jiffies)
+static __always_inline cputime_t steal_account_process_time(cputime_t maxtime)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(&paravirt_steal_enabled)) {
+ cputime_t steal_cputime;
u64 steal;
- unsigned long steal_jiffies;
steal = paravirt_steal_clock(smp_processor_id());
steal -= this_rq()->prev_steal_time;
- /*
- * steal is in nsecs but our caller is expecting steal
- * time in jiffies. Lets cast the result to jiffies
- * granularity and account the rest on the next rounds.
- */
- steal_jiffies = min(nsecs_to_jiffies(steal), max_jiffies);
- this_rq()->prev_steal_time += jiffies_to_nsecs(steal_jiffies);
+ steal_cputime = min(nsecs_to_cputime(steal), maxtime);
+ account_steal_time(steal_cputime);
+ this_rq()->prev_steal_time += cputime_to_nsecs(steal_cputime);
- account_steal_time(jiffies_to_cputime(steal_jiffies));
- return steal_jiffies;
+ return steal_cputime;
}
#endif
return 0;
}
/*
+ * Account how much elapsed time was spent in steal, irq, or softirq time.
+ */
+static inline cputime_t account_other_time(cputime_t max)
+{
+ cputime_t accounted;
+
+ accounted = steal_account_process_time(max);
+
+ if (accounted < max)
+ accounted += irqtime_account_hi_update(max - accounted);
+
+ if (accounted < max)
+ accounted += irqtime_account_si_update(max - accounted);
+
+ return accounted;
+}
+
+/*
* Accumulate raw cputime values of dead tasks (sig->[us]time) and live
* tasks (sum on group iteration) belonging to @tsk's group.
*/
@@ -342,21 +361,23 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
struct rq *rq, int ticks)
{
- cputime_t scaled = cputime_to_scaled(cputime_one_jiffy);
- u64 cputime = (__force u64) cputime_one_jiffy;
- u64 *cpustat = kcpustat_this_cpu->cpustat;
+ u64 cputime = (__force u64) cputime_one_jiffy * ticks;
+ cputime_t scaled, other;
- if (steal_account_process_tick(ULONG_MAX))
+ /*
+ * When returning from idle, many ticks can get accounted at
+ * once, including some ticks of steal, irq, and softirq time.
+ * Subtract those ticks from the amount of time accounted to
+ * idle, or potentially user or system time. Due to rounding,
+ * other time can exceed ticks occasionally.
+ */
+ other = account_other_time(cputime);
+ if (other >= cputime)
return;
+ cputime -= other;
+ scaled = cputime_to_scaled(cputime);
- cputime *= ticks;
- scaled *= ticks;
-
- if (irqtime_account_hi_update()) {
- cpustat[CPUTIME_IRQ] += cputime;
- } else if (irqtime_account_si_update()) {
- cpustat[CPUTIME_SOFTIRQ] += cputime;
- } else if (this_cpu_ksoftirqd() == p) {
+ if (this_cpu_ksoftirqd() == p) {
/*
* ksoftirqd time do not get accounted in cpu_softirq_time.
* So, we have to handle it separately here.
@@ -406,6 +427,10 @@ void vtime_common_task_switch(struct task_struct *prev)
}
#endif
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
+
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
/*
* Archs that account the whole time spent in the idle task
* (outside irq) as idle time can rely on this and just implement
@@ -415,33 +440,16 @@ void vtime_common_task_switch(struct task_struct *prev)
* vtime_account().
*/
#ifndef __ARCH_HAS_VTIME_ACCOUNT
-void vtime_common_account_irq_enter(struct task_struct *tsk)
+void vtime_account_irq_enter(struct task_struct *tsk)
{
- if (!in_interrupt()) {
- /*
- * If we interrupted user, context_tracking_in_user()
- * is 1 because the context tracking don't hook
- * on irq entry/exit. This way we know if
- * we need to flush user time on kernel entry.
- */
- if (context_tracking_in_user()) {
- vtime_account_user(tsk);
- return;
- }
-
- if (is_idle_task(tsk)) {
- vtime_account_idle(tsk);
- return;
- }
- }
- vtime_account_system(tsk);
+ if (!in_interrupt() && is_idle_task(tsk))
+ vtime_account_idle(tsk);
+ else
+ vtime_account_system(tsk);
}
-EXPORT_SYMBOL_GPL(vtime_common_account_irq_enter);
+EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
#endif /* __ARCH_HAS_VTIME_ACCOUNT */
-#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
-
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
*ut = p->utime;
@@ -466,7 +474,7 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime
*/
void account_process_tick(struct task_struct *p, int user_tick)
{
- cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
+ cputime_t cputime, scaled, steal;
struct rq *rq = this_rq();
if (vtime_accounting_cpu_enabled())
@@ -477,16 +485,21 @@ void account_process_tick(struct task_struct *p, int user_tick)
return;
}
- if (steal_account_process_tick(ULONG_MAX))
+ cputime = cputime_one_jiffy;
+ steal = steal_account_process_time(cputime);
+
+ if (steal >= cputime)
return;
+ cputime -= steal;
+ scaled = cputime_to_scaled(cputime);
+
if (user_tick)
- account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
+ account_user_time(p, cputime, scaled);
else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
- account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
- one_jiffy_scaled);
+ account_system_time(p, HARDIRQ_OFFSET, cputime, scaled);
else
- account_idle_time(cputime_one_jiffy);
+ account_idle_time(cputime);
}
/*
@@ -681,14 +694,14 @@ static cputime_t vtime_delta(struct task_struct *tsk)
static cputime_t get_vtime_delta(struct task_struct *tsk)
{
unsigned long now = READ_ONCE(jiffies);
- unsigned long delta_jiffies, steal_jiffies;
+ cputime_t delta, other;
- delta_jiffies = now - tsk->vtime_snap;
- steal_jiffies = steal_account_process_tick(delta_jiffies);
+ delta = jiffies_to_cputime(now - tsk->vtime_snap);
+ other = account_other_time(delta);
WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
tsk->vtime_snap = now;
- return jiffies_to_cputime(delta_jiffies - steal_jiffies);
+ return delta - other;
}
static void __vtime_account_system(struct task_struct *tsk)
@@ -708,16 +721,6 @@ void vtime_account_system(struct task_struct *tsk)
write_seqcount_end(&tsk->vtime_seqcount);
}
-void vtime_gen_account_irq_exit(struct task_struct *tsk)
-{
- write_seqcount_begin(&tsk->vtime_seqcount);
- if (vtime_delta(tsk))
- __vtime_account_system(tsk);
- if (context_tracking_in_user())
- tsk->vtime_snap_whence = VTIME_USER;
- write_seqcount_end(&tsk->vtime_seqcount);
-}
-
void vtime_account_user(struct task_struct *tsk)
{
cputime_t delta_cpu;