Latencies of missed timer offsets. Generate a histogram of missed
timer offsets in microseconds. This will be a based along with irq
and preemption latencies to calculate the effective process wakeup
latencies.
The following filter(s) may be used
'hist:key=common_pid.execname'
'hist:key=common_pid.execname,cpu:val=toffset,hitcount'
Signed-off-by: Binoy Jayan <binoy.ja...@linaro.org>
---
include/linux/hrtimer.h | 3 +++
include/trace/events/latency.h | 31 +++++++++++++++++++++++++++++++
kernel/time/hrtimer.c | 39 +++++++++++++++++++++++++++++++++++++++
3 files changed, 73 insertions(+)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 5e00f80..e09de14 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -104,6 +104,9 @@ struct hrtimer {
struct hrtimer_clock_base *base;
u8 state;
u8 is_rel;
+#if defined(CONFIG_PREEMPT_TRACER) || defined(CONFIG_IRQSOFF_TRACER)
+ ktime_t praecox;
+#endif
#ifdef CONFIG_TIMER_STATS
int start_pid;
void *start_site;
diff --git a/include/trace/events/latency.h b/include/trace/events/latency.h
index 77896c7..24cf009 100644
--- a/include/trace/events/latency.h
+++ b/include/trace/events/latency.h
@@ -37,6 +37,37 @@ DEFINE_EVENT(latency_template, latency_critical_timings,
TP_PROTO(int cpu, cycles_t latency),
TP_ARGS(cpu, latency));
+TRACE_EVENT(latency_hrtimer_interrupt,
+
+ TP_PROTO(int cpu, long long toffset, struct task_struct *curr,
+ struct task_struct *task),
+
+ TP_ARGS(cpu, toffset, curr, task),
+
+ TP_STRUCT__entry(
+ __field(int, cpu)
+ __field(long long, toffset)
+ __array(char, ccomm, TASK_COMM_LEN)
+ __field(int, cprio)
+ __array(char, tcomm, TASK_COMM_LEN)
+ __field(int, tprio)
+ ),
+
+ TP_fast_assign(
+ __entry->cpu = cpu;
+ __entry->toffset = toffset;
+ memcpy(__entry->ccomm, curr->comm, TASK_COMM_LEN);
+ __entry->cprio = curr->prio;
+ memcpy(__entry->tcomm, task != NULL ? task->comm : "<none>",
+ task != NULL ? TASK_COMM_LEN : 7);
+ __entry->tprio = task != NULL ? task->prio : -1;
+ ),
+
+ TP_printk("cpu=%d toffset=%lld curr=%s[%d] thread=%s[%d]",
+ __entry->cpu, __entry->toffset, __entry->ccomm,
+ __entry->cprio, __entry->tcomm, __entry->tprio)
+);
+
#endif /* _TRACE_HIST_H */
/* This part must be outside protection */
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 9ba7c82..1a96e34 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -53,9 +53,12 @@
#include <asm/uaccess.h>
#include <trace/events/timer.h>
+#include <trace/events/latency.h>
#include "tick-internal.h"
+static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer);
+
/*
* The timer bases:
*
@@ -960,6 +963,38 @@ static inline ktime_t hrtimer_update_lowres(struct hrtimer
*timer, ktime_t tim,
return tim;
}
+static inline void trace_latency_mark_ts(struct hrtimer *timer,
+ struct hrtimer_clock_base *new_base,
+ ktime_t tim)
+{
+#if defined(CONFIG_PREEMPT_TRACER) || defined(CONFIG_IRQSOFF_TRACER)
+ if (trace_latency_hrtimer_interrupt_enabled()) {
+ ktime_t now = new_base->get_time();
+
+ if (ktime_to_ns(tim) < ktime_to_ns(now))
+ timer->praecox = now;
+ else
+ timer->praecox = ktime_set(0, 0);
+ }
+#endif
+}
+
+static inline void trace_missed_hrtimer(struct hrtimer *timer, ktime_t basenow)
+{
+#if defined(CONFIG_PREEMPT_TRACER) || defined(CONFIG_IRQSOFF_TRACER)
+ if (trace_latency_hrtimer_interrupt_enabled())
+ trace_latency_hrtimer_interrupt(raw_smp_processor_id(),
+ ktime_to_ns(ktime_sub(ktime_to_ns(timer->praecox) ?
+ timer->praecox : hrtimer_get_expires(timer),
+ basenow)),
+ current,
+ timer->function == hrtimer_wakeup ?
+ container_of(timer, struct hrtimer_sleeper,
+ timer)->task : NULL);
+#endif
+
+}
+
/**
* hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
* @timer: the timer to be added
@@ -992,6 +1027,8 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t
tim,
timer_stats_hrtimer_set_start_info(timer);
+ trace_latency_mark_ts(timer, new_base, tim);
+
leftmost = enqueue_hrtimer(timer, new_base);
if (!leftmost)
goto unlock;
@@ -1284,6 +1321,8 @@ static void __hrtimer_run_queues(struct hrtimer_cpu_base
*cpu_base, ktime_t now)
timer = container_of(node, struct hrtimer, node);
+ trace_missed_hrtimer(timer, basenow);
+
/*
* The immediate goal for using the softexpires is
* minimizing wakeups, not running timers at the
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
