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Message-Id: <1469681535-25159-2-git-send-email-binoy.jayan@linaro.org>
Date: Thu, 28 Jul 2016 10:22:13 +0530
From: Binoy Jayan <binoy.jayan@...aro.org>
To: Steven Rostedt <srostedt@...hat.com>
Cc: linux-kernel@...r.kernel.org, Carsten Emde <C.Emde@...dl.org>,
Thomas Gleixner <tglx@...utronix.de>,
Binoy Jayan <binoy.jayan@...aro.org>
Subject: [PATCH 1/2] tracing: Add latency histograms
From: Carsten Emde <C.Emde@...dl.org>
This patch provides a recording mechanism to store data of potential
sources of system latencies. The recordings separately determine the
latency caused by a delayed timer expiration, by a delayed wakeup of the
related user space program and by the sum of both. The histograms can be
enabled and reset individually. The data are accessible via the debug
filesystem. The patch is adapted from the rt kernel and restructured to
avoid unwanted macros from source files. For details please consult
Documentation/trace/histograms.txt.
Signed-off-by: Carsten Emde <C.Emde@...dl.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Binoy Jayan <binoy.jayan@...aro.org>
---
Documentation/trace/histograms.txt | 186 ++++++
include/linux/hrtimer.h | 3 +
include/linux/sched.h | 6 +
include/trace/events/hist.h | 72 +++
include/trace/events/latency_hist.h | 136 +++++
kernel/time/hrtimer.c | 20 +
kernel/trace/Kconfig | 104 ++++
kernel/trace/Makefile | 4 +
kernel/trace/latency_hist.c | 1091 +++++++++++++++++++++++++++++++++++
kernel/trace/trace_irqsoff.c | 9 +
10 files changed, 1631 insertions(+)
create mode 100644 Documentation/trace/histograms.txt
create mode 100644 include/trace/events/hist.h
create mode 100644 include/trace/events/latency_hist.h
create mode 100644 kernel/trace/latency_hist.c
diff --git a/Documentation/trace/histograms.txt b/Documentation/trace/histograms.txt
new file mode 100644
index 0000000..60644ff
--- /dev/null
+++ b/Documentation/trace/histograms.txt
@@ -0,0 +1,186 @@
+ Using the Linux Kernel Latency Histograms
+
+
+This document gives a short explanation how to enable, configure and use
+latency histograms. Latency histograms are primarily relevant in the
+context of real-time enabled kernels (CONFIG_PREEMPT/CONFIG_PREEMPT_RT)
+and are used in the quality management of the Linux real-time
+capabilities.
+
+
+* Purpose of latency histograms
+
+A latency histogram continuously accumulates the frequencies of latency
+data. There are two types of histograms
+- potential sources of latencies
+- effective latencies
+
+
+* Potential sources of latencies
+
+Potential sources of latencies are code segments where interrupts,
+preemption or both are disabled (aka critical sections). To create
+histograms of potential sources of latency, the kernel stores the time
+stamp at the start of a critical section, determines the time elapsed
+when the end of the section is reached, and increments the frequency
+counter of that latency value - irrespective of whether any concurrently
+running process is affected by latency or not.
+- Configuration items (in the Kernel hacking/Tracers submenu)
+ CONFIG_INTERRUPT_OFF_LATENCY
+ CONFIG_PREEMPT_OFF_LATENCY
+
+
+* Effective latencies
+
+Effective latencies are actually occurring during wakeup of a process. To
+determine effective latencies, the kernel stores the time stamp when a
+process is scheduled to be woken up, and determines the duration of the
+wakeup time shortly before control is passed over to this process. Note
+that the apparent latency in user space may be somewhat longer, since the
+process may be interrupted after control is passed over to it but before
+the execution in user space takes place. Simply measuring the interval
+between enqueuing and wakeup may also not appropriate in cases when a
+process is scheduled as a result of a timer expiration. The timer may have
+missed its deadline, e.g. due to disabled interrupts, but this latency
+would not be registered. Therefore, the offsets of missed timers are
+recorded in a separate histogram. If both wakeup latency and missed timer
+offsets are configured and enabled, a third histogram may be enabled that
+records the overall latency as a sum of the timer latency, if any, and the
+wakeup latency. This histogram is called "timerandwakeup".
+- Configuration items (in the Kernel hacking/Tracers submenu)
+ CONFIG_WAKEUP_LATENCY
+ CONFIG_MISSED_TIMER_OFSETS
+
+
+* Usage
+
+The interface to the administration of the latency histograms is located
+in the debugfs file system. To mount it, either enter
+
+mount -t sysfs nodev /sys
+mount -t debugfs nodev /sys/kernel/debug
+
+from shell command line level, or add
+
+nodev /sys sysfs defaults 0 0
+nodev /sys/kernel/debug debugfs defaults 0 0
+
+to the file /etc/fstab. All latency histogram related files are then
+available in the directory /sys/kernel/debug/tracing/latency_hist. A
+particular histogram type is enabled by writing non-zero to the related
+variable in the /sys/kernel/debug/tracing/latency_hist/enable directory.
+Select "preemptirqsoff" for the histograms of potential sources of
+latencies and "wakeup" for histograms of effective latencies etc. The
+histogram data - one per CPU - are available in the files
+
+/sys/kernel/debug/tracing/latency_hist/preemptoff/CPUx
+/sys/kernel/debug/tracing/latency_hist/irqsoff/CPUx
+/sys/kernel/debug/tracing/latency_hist/preemptirqsoff/CPUx
+/sys/kernel/debug/tracing/latency_hist/wakeup/CPUx
+/sys/kernel/debug/tracing/latency_hist/wakeup/sharedprio/CPUx
+/sys/kernel/debug/tracing/latency_hist/missed_timer_offsets/CPUx
+/sys/kernel/debug/tracing/latency_hist/timerandwakeup/CPUx
+
+The histograms are reset by writing non-zero to the file "reset" in a
+particular latency directory. To reset all latency data, use
+
+#!/bin/sh
+
+TRACINGDIR=/sys/kernel/debug/tracing
+HISTDIR=$TRACINGDIR/latency_hist
+
+if test -d $HISTDIR
+then
+ cd $HISTDIR
+ for i in `find . | grep /reset$`
+ do
+ echo 1 >$i
+ done
+fi
+
+
+* Data format
+
+Latency data are stored with a resolution of one microsecond. The
+maximum latency is 10,240 microseconds. The data are only valid, if the
+overflow register is empty. Every output line contains the latency in
+microseconds in the first row and the number of samples in the second
+row. To display only lines with a positive latency count, use, for
+example,
+
+grep -v " 0$" /sys/kernel/debug/tracing/latency_hist/preemptoff/CPU0
+
+#Minimum latency: 0 microseconds.
+#Average latency: 0 microseconds.
+#Maximum latency: 25 microseconds.
+#Total samples: 3104770694
+#There are 0 samples greater or equal than 10240 microseconds
+#usecs samples
+ 0 2984486876
+ 1 49843506
+ 2 58219047
+ 3 5348126
+ 4 2187960
+ 5 3388262
+ 6 959289
+ 7 208294
+ 8 40420
+ 9 4485
+ 10 14918
+ 11 18340
+ 12 25052
+ 13 19455
+ 14 5602
+ 15 969
+ 16 47
+ 17 18
+ 18 14
+ 19 1
+ 20 3
+ 21 2
+ 22 5
+ 23 2
+ 25 1
+
+
+* Wakeup latency of a selected process
+
+To only collect wakeup latency data of a particular process, write the
+PID of the requested process to
+
+/sys/kernel/debug/tracing/latency_hist/wakeup/pid
+
+PIDs are not considered, if this variable is set to 0.
+
+
+* Details of the process with the highest wakeup latency so far
+
+Selected data of the process that suffered from the highest wakeup
+latency that occurred in a particular CPU are available in the file
+
+/sys/kernel/debug/tracing/latency_hist/wakeup/max_latency-CPUx.
+
+In addition, other relevant system data at the time when the
+latency occurred are given.
+
+The format of the data is (all in one line):
+<PID> <Priority> <Latency> (<Timeroffset>) <Command> \
+<- <PID> <Priority> <Command> <Timestamp>
+
+The value of <Timeroffset> is only relevant in the combined timer
+and wakeup latency recording. In the wakeup recording, it is
+always 0, in the missed_timer_offsets recording, it is the same
+as <Latency>.
+
+When retrospectively searching for the origin of a latency and
+tracing was not enabled, it may be helpful to know the name and
+some basic data of the task that (finally) was switching to the
+late real-tlme task. In addition to the victim's data, also the
+data of the possible culprit are therefore displayed after the
+"<-" symbol.
+
+Finally, the timestamp of the time when the latency occurred
+in <seconds>.<microseconds> after the most recent system boot
+is provided.
+
+These data are also reset when the wakeup histogram is reset.
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index c98c653..f73935b 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;
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+ ktime_t praecox;
+#endif
#ifdef CONFIG_TIMER_STATS
int start_pid;
void *start_site;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 253538f..a96735b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1885,6 +1885,12 @@ struct task_struct {
unsigned long trace;
/* bitmask and counter of trace recursion */
unsigned long trace_recursion;
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+ u64 preempt_timestamp_hist;
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+ long timer_offset;
+#endif
+#endif
#endif /* CONFIG_TRACING */
#ifdef CONFIG_KCOV
/* Coverage collection mode enabled for this task (0 if disabled). */
diff --git a/include/trace/events/hist.h b/include/trace/events/hist.h
new file mode 100644
index 0000000..6122e42
--- /dev/null
+++ b/include/trace/events/hist.h
@@ -0,0 +1,72 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM hist
+
+#if !defined(_TRACE_HIST_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_HIST_H
+
+#include "latency_hist.h"
+#include <linux/tracepoint.h>
+
+#if !defined(CONFIG_PREEMPT_OFF_HIST) && !defined(CONFIG_INTERRUPT_OFF_HIST)
+#define trace_preemptirqsoff_hist(a, b)
+#else
+TRACE_EVENT(preemptirqsoff_hist,
+
+ TP_PROTO(int reason, int starthist),
+
+ TP_ARGS(reason, starthist),
+
+ TP_STRUCT__entry(
+ __field(int, reason)
+ __field(int, starthist)
+ ),
+
+ TP_fast_assign(
+ __entry->reason = reason;
+ __entry->starthist = starthist;
+ ),
+
+ TP_printk("reason=%s starthist=%s", getaction(__entry->reason),
+ __entry->starthist ? "start" : "stop")
+);
+#endif
+
+#ifndef CONFIG_MISSED_TIMER_OFFSETS_HIST
+#define trace_hrtimer_interrupt(a, b, c, d)
+#else
+TRACE_EVENT(hrtimer_interrupt,
+
+ TP_PROTO(int cpu, long long offset, struct task_struct *curr,
+ struct task_struct *task),
+
+ TP_ARGS(cpu, offset, curr, task),
+
+ TP_STRUCT__entry(
+ __field(int, cpu)
+ __field(long long, offset)
+ __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->offset = offset;
+ 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 offset=%lld curr=%s[%d] thread=%s[%d]",
+ __entry->cpu, __entry->offset, __entry->ccomm,
+ __entry->cprio, __entry->tcomm, __entry->tprio)
+);
+#endif
+
+#endif /* _TRACE_HIST_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/include/trace/events/latency_hist.h b/include/trace/events/latency_hist.h
new file mode 100644
index 0000000..6478496
--- /dev/null
+++ b/include/trace/events/latency_hist.h
@@ -0,0 +1,136 @@
+#ifndef _LATENCY_HIST_H
+#define _LATENCY_HIST_H
+
+enum hist_action {
+ IRQS_ON,
+ PREEMPT_ON,
+ TRACE_STOP,
+ IRQS_OFF,
+ PREEMPT_OFF,
+ TRACE_START,
+};
+
+static char *actions[] = {
+ "IRQS_ON",
+ "PREEMPT_ON",
+ "TRACE_STOP",
+ "IRQS_OFF",
+ "PREEMPT_OFF",
+ "TRACE_START",
+};
+
+enum {
+ IRQSOFF_LATENCY = 0,
+ PREEMPTOFF_LATENCY,
+ PREEMPTIRQSOFF_LATENCY,
+ WAKEUP_LATENCY,
+ WAKEUP_LATENCY_SHAREDPRIO,
+ MISSED_TIMER_OFFSETS,
+ TIMERANDWAKEUP_LATENCY,
+ MAX_LATENCY_TYPE,
+};
+
+#define MAX_ENTRY_NUM 10240
+
+struct hist_data {
+ atomic_t hist_mode; /* 0 log, 1 don't log */
+ long offset; /* set it to MAX_ENTRY_NUM/2 for a bipolar scale */
+ long min_lat;
+ long max_lat;
+ unsigned long long below_hist_bound_samples;
+ unsigned long long above_hist_bound_samples;
+ long long accumulate_lat;
+ unsigned long long total_samples;
+ unsigned long long hist_array[MAX_ENTRY_NUM];
+};
+
+struct enable_data {
+ int latency_type;
+ int enabled;
+};
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+ defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+struct maxlatproc_data {
+ char comm[FIELD_SIZEOF(struct task_struct, comm)];
+ char current_comm[FIELD_SIZEOF(struct task_struct, comm)];
+ int pid;
+ int current_pid;
+ int prio;
+ int current_prio;
+ long latency;
+ long timeroffset;
+ cycle_t timestamp;
+};
+extern void clear_maxlatprocdata(struct maxlatproc_data *mp);
+extern ssize_t
+show_pid(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos);
+extern ssize_t
+show_maxlatproc(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos);
+#else
+void clear_maxlatprocdata(struct maxlatproc_data *mp)
+{
+}
+static ssize_t
+show_pid(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+}
+static ssize_t
+show_maxlatproc(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+}
+#endif
+
+#if defined(CONFIG_INTERRUPT_OFF_HIST) || defined(CONFIG_PREEMPT_OFF_HIST)
+extern notrace void probe_preemptirqsoff_hist(void *v, int reason,
+ int starthist);
+#else
+static notrace void probe_preemptirqsoff_hist(void *v, int reason,
+ int starthist)
+{
+}
+#endif
+
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+extern notrace void probe_sched_migrate_task(void *v, struct task_struct *task,
+ int cpu);
+extern notrace void probe_wakeup_latency_hist_start(void *v,
+ struct task_struct *p);
+extern notrace void probe_wakeup_latency_hist_stop(void *v, bool preempt,
+ struct task_struct *prev, struct task_struct *next);
+#else
+static notrace void probe_sched_migrate_task(void *v, struct task_struct *task,
+ int cpu)
+{
+}
+static notrace void probe_wakeup_latency_hist_start(void *v,
+ struct task_struct *p)
+{
+}
+static notrace void probe_wakeup_latency_hist_stop(void *v, bool preempt,
+ struct task_struct *prev, struct task_struct *next)
+{
+}
+#endif
+
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+extern notrace void probe_hrtimer_interrupt(void *v, int cpu,
+ long long latency_ns, struct task_struct *curr,
+ struct task_struct *task);
+#else
+static notrace void probe_hrtimer_interrupt(void *v, int cpu,
+ long long latency_ns, struct task_struct *curr,
+ struct task_struct *task)
+{
+}
+#endif
+
+static inline char *getaction(int action)
+{
+ if (action >= 0 && action <= ARRAY_SIZE(actions))
+ return actions[action];
+ return "unknown";
+}
+
+#endif /* _LATENCY_HIST_H */
+
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index e99df0f..0a0ca23 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -53,6 +53,7 @@
#include <asm/uaccess.h>
#include <trace/events/timer.h>
+#include <trace/events/hist.h>
#include "tick-internal.h"
@@ -991,6 +992,14 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
timer_stats_hrtimer_set_start_info(timer);
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ 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);
+ }
leftmost = enqueue_hrtimer(timer, new_base);
if (!leftmost)
@@ -1265,6 +1274,8 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
cpu_base->running = NULL;
}
+static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer);
+
static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
{
struct hrtimer_clock_base *base = cpu_base->clock_base;
@@ -1284,6 +1295,15 @@ static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
timer = container_of(node, struct hrtimer, node);
+ trace_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);
+
/*
* The immediate goal for using the softexpires is
* minimizing wakeups, not running timers at the
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index fafeaf8..ae80502 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -187,6 +187,24 @@ config IRQSOFF_TRACER
enabled. This option and the preempt-off timing option can be
used together or separately.)
+config INTERRUPT_OFF_HIST
+ bool "Interrupts-off Latency Histogram"
+ depends on IRQSOFF_TRACER
+ help
+ This option generates continuously updated histograms (one per cpu)
+ of the duration of time periods with interrupts disabled. The
+ histograms are disabled by default. To enable them, write a non-zero
+ number to
+
+ /sys/kernel/debug/tracing/latency_hist/enable/preemptirqsoff
+
+ If PREEMPT_OFF_HIST is also selected, additional histograms (one
+ per cpu) are generated that accumulate the duration of time periods
+ when both interrupts and preemption are disabled. The histogram data
+ will be located in the debug file system at
+
+ /sys/kernel/debug/tracing/latency_hist/irqsoff
+
config PREEMPT_TRACER
bool "Preemption-off Latency Tracer"
default n
@@ -211,6 +229,24 @@ config PREEMPT_TRACER
enabled. This option and the irqs-off timing option can be
used together or separately.)
+config PREEMPT_OFF_HIST
+ bool "Preemption-off Latency Histogram"
+ depends on PREEMPT_TRACER
+ help
+ This option generates continuously updated histograms (one per cpu)
+ of the duration of time periods with preemption disabled. The
+ histograms are disabled by default. To enable them, write a non-zero
+ number to
+
+ /sys/kernel/debug/tracing/latency_hist/enable/preemptirqsoff
+
+ If INTERRUPT_OFF_HIST is also selected, additional histograms (one
+ per cpu) are generated that accumulate the duration of time periods
+ when both interrupts and preemption are disabled. The histogram data
+ will be located in the debug file system at
+
+ /sys/kernel/debug/tracing/latency_hist/preemptoff
+
config SCHED_TRACER
bool "Scheduling Latency Tracer"
select GENERIC_TRACER
@@ -221,6 +257,74 @@ config SCHED_TRACER
This tracer tracks the latency of the highest priority task
to be scheduled in, starting from the point it has woken up.
+config WAKEUP_LATENCY_HIST
+ bool "Scheduling Latency Histogram"
+ depends on SCHED_TRACER
+ help
+ This option generates continuously updated histograms (one per cpu)
+ of the scheduling latency of the highest priority task.
+ The histograms are disabled by default. To enable them, write a
+ non-zero number to
+
+ /sys/kernel/debug/tracing/latency_hist/enable/wakeup
+
+ Two different algorithms are used, one to determine the latency of
+ processes that exclusively use the highest priority of the system and
+ another one to determine the latency of processes that share the
+ highest system priority with other processes. The former is used to
+ improve hardware and system software, the latter to optimize the
+ priority design of a given system. The histogram data will be
+ located in the debug file system at
+
+ /sys/kernel/debug/tracing/latency_hist/wakeup
+
+ and
+
+ /sys/kernel/debug/tracing/latency_hist/wakeup/sharedprio
+
+ If both Scheduling Latency Histogram and Missed Timer Offsets
+ Histogram are selected, additional histogram data will be collected
+ that contain, in addition to the wakeup latency, the timer latency, in
+ case the wakeup was triggered by an expired timer. These histograms
+ are available in the
+
+ /sys/kernel/debug/tracing/latency_hist/timerandwakeup
+
+ directory. They reflect the apparent interrupt and scheduling latency
+ and are best suitable to determine the worst-case latency of a given
+ system. To enable these histograms, write a non-zero number to
+
+ /sys/kernel/debug/tracing/latency_hist/enable/timerandwakeup
+
+config MISSED_TIMER_OFFSETS_HIST
+ depends on HIGH_RES_TIMERS
+ select GENERIC_TRACER
+ bool "Missed Timer Offsets Histogram"
+ help
+ Generate a histogram of missed timer offsets in microseconds. The
+ histograms are disabled by default. To enable them, write a non-zero
+ number to
+
+ /sys/kernel/debug/tracing/latency_hist/enable/missed_timer_offsets
+
+ The histogram data will be located in the debug file system at
+
+ /sys/kernel/debug/tracing/latency_hist/missed_timer_offsets
+
+ If both Scheduling Latency Histogram and Missed Timer Offsets
+ Histogram are selected, additional histogram data will be collected
+ that contain, in addition to the wakeup latency, the timer latency, in
+ case the wakeup was triggered by an expired timer. These histograms
+ are available in the
+
+ /sys/kernel/debug/tracing/latency_hist/timerandwakeup
+
+ directory. They reflect the apparent interrupt and scheduling latency
+ and are best suitable to determine the worst-case latency of a given
+ system. To enable these histograms, write a non-zero number to
+
+ /sys/kernel/debug/tracing/latency_hist/enable/timerandwakeup
+
config ENABLE_DEFAULT_TRACERS
bool "Trace process context switches and events"
depends on !GENERIC_TRACER
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 979e7bf..1a27aad 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -37,6 +37,10 @@ obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
+obj-$(CONFIG_INTERRUPT_OFF_HIST) += latency_hist.o
+obj-$(CONFIG_PREEMPT_OFF_HIST) += latency_hist.o
+obj-$(CONFIG_WAKEUP_LATENCY_HIST) += latency_hist.o
+obj-$(CONFIG_MISSED_TIMER_OFFSETS_HIST) += latency_hist.o
obj-$(CONFIG_NOP_TRACER) += trace_nop.o
obj-$(CONFIG_STACK_TRACER) += trace_stack.o
obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
diff --git a/kernel/trace/latency_hist.c b/kernel/trace/latency_hist.c
new file mode 100644
index 0000000..45a6b9f
--- /dev/null
+++ b/kernel/trace/latency_hist.c
@@ -0,0 +1,1091 @@
+/*
+ * kernel/trace/latency_hist.c
+ *
+ * Add support for histograms of preemption-off latency and
+ * interrupt-off latency and wakeup latency, it depends on
+ * Real-Time Preemption Support.
+ *
+ * Copyright (C) 2005 MontaVista Software, Inc.
+ * Yi Yang <yyang@...mvista.com>
+ *
+ * Converted to work with the new latency tracer.
+ * Copyright (C) 2008 Red Hat, Inc.
+ * Steven Rostedt <srostedt@...hat.com>
+ *
+ */
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/percpu.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/slab.h>
+#include <linux/atomic.h>
+#include <asm/div64.h>
+
+#include "trace.h"
+#include <trace/events/sched.h>
+
+#define NSECS_PER_USECS 1000L
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/hist.h>
+
+static char *latency_hist_dir_root = "latency_hist";
+
+static int __maybe_unused one = 1;
+
+static DEFINE_PER_CPU(struct __maybe_unused hist_data, irqsoff_hist);
+static char *irqsoff_hist_dir __maybe_unused = "irqsoff";
+static DEFINE_PER_CPU(cycles_t __maybe_unused, hist_irqsoff_start);
+static DEFINE_PER_CPU(int __maybe_unused, hist_irqsoff_counting);
+
+static DEFINE_PER_CPU(struct __maybe_unused hist_data, preemptoff_hist);
+static char *preemptoff_hist_dir __maybe_unused = "preemptoff";
+static DEFINE_PER_CPU(cycles_t __maybe_unused, hist_preemptoff_start);
+static DEFINE_PER_CPU(int __maybe_unused, hist_preemptoff_counting);
+
+static DEFINE_PER_CPU(struct __maybe_unused hist_data, preemptirqsoff_hist);
+static char *preemptirqsoff_hist_dir __maybe_unused = "preemptirqsoff";
+static DEFINE_PER_CPU(cycles_t __maybe_unused, hist_preemptirqsoff_start);
+static DEFINE_PER_CPU(int __maybe_unused, hist_preemptirqsoff_counting);
+
+static struct enable_data __maybe_unused preemptirqsoff_enabled_data = {
+ .latency_type = PREEMPTIRQSOFF_LATENCY,
+ .enabled = 0,
+};
+
+static DEFINE_PER_CPU(struct __maybe_unused hist_data, wakeup_latency_hist);
+static DEFINE_PER_CPU(struct __maybe_unused hist_data,
+ wakeup_latency_hist_sharedprio);
+static char *wakeup_latency_hist_dir __maybe_unused = "wakeup";
+static char *wakeup_latency_hist_dir_sharedprio __maybe_unused = "sharedprio";
+static struct enable_data __maybe_unused wakeup_latency_enabled_data = {
+ .latency_type = WAKEUP_LATENCY,
+ .enabled = 0,
+};
+
+static DEFINE_PER_CPU(struct maxlatproc_data, wakeup_maxlatproc);
+static DEFINE_PER_CPU(struct maxlatproc_data, wakeup_maxlatproc_sharedprio);
+static DEFINE_PER_CPU(struct task_struct *, wakeup_task);
+static DEFINE_PER_CPU(int, wakeup_sharedprio);
+static unsigned long wakeup_pid;
+
+static DEFINE_PER_CPU(struct __maybe_unused hist_data, missed_timer_offsets);
+static char *missed_timer_offsets_dir __maybe_unused = "missed_timer_offsets";
+static struct enable_data __maybe_unused missed_timer_offsets_enabled_data = {
+ .latency_type = MISSED_TIMER_OFFSETS,
+ .enabled = 0,
+};
+static DEFINE_PER_CPU(struct __maybe_unused maxlatproc_data,
+ missed_timer_offsets_maxlatproc);
+static unsigned long __maybe_unused missed_timer_offsets_pid;
+
+static DEFINE_PER_CPU(struct __maybe_unused hist_data,
+ timerandwakeup_latency_hist);
+static char *timerandwakeup_latency_hist_dir __maybe_unused = "timerandwakeup";
+static struct enable_data __maybe_unused timerandwakeup_enabled_data = {
+ .latency_type = TIMERANDWAKEUP_LATENCY,
+ .enabled = 0,
+};
+static DEFINE_PER_CPU(struct __maybe_unused maxlatproc_data,
+ timerandwakeup_maxlatproc);
+
+void notrace latency_hist(int latency_type, int cpu, long latency,
+ long timeroffset, cycle_t stop,
+ struct task_struct *p)
+{
+ struct hist_data *my_hist;
+ struct maxlatproc_data *mp __maybe_unused = NULL;
+
+ if (!cpu_possible(cpu) || latency_type < 0 ||
+ latency_type >= MAX_LATENCY_TYPE)
+ return;
+
+ switch (latency_type) {
+ case IRQSOFF_LATENCY:
+ my_hist = &per_cpu(irqsoff_hist, cpu);
+ break;
+ case PREEMPTOFF_LATENCY:
+ my_hist = &per_cpu(preemptoff_hist, cpu);
+ break;
+ case PREEMPTIRQSOFF_LATENCY:
+ my_hist = &per_cpu(preemptirqsoff_hist, cpu);
+ break;
+ case WAKEUP_LATENCY:
+ my_hist = &per_cpu(wakeup_latency_hist, cpu);
+ mp = &per_cpu(wakeup_maxlatproc, cpu);
+ break;
+ case WAKEUP_LATENCY_SHAREDPRIO:
+ my_hist = &per_cpu(wakeup_latency_hist_sharedprio, cpu);
+ mp = &per_cpu(wakeup_maxlatproc_sharedprio, cpu);
+ break;
+ case MISSED_TIMER_OFFSETS:
+ my_hist = &per_cpu(missed_timer_offsets, cpu);
+ mp = &per_cpu(missed_timer_offsets_maxlatproc, cpu);
+ break;
+ case TIMERANDWAKEUP_LATENCY:
+ my_hist = &per_cpu(timerandwakeup_latency_hist, cpu);
+ mp = &per_cpu(timerandwakeup_maxlatproc, cpu);
+ break;
+ default:
+ return;
+ }
+
+ latency += my_hist->offset;
+
+ if (atomic_read(&my_hist->hist_mode) == 0)
+ return;
+
+ if (latency < 0 || latency >= MAX_ENTRY_NUM) {
+ if (latency < 0)
+ my_hist->below_hist_bound_samples++;
+ else
+ my_hist->above_hist_bound_samples++;
+ } else
+ my_hist->hist_array[latency]++;
+
+ if (unlikely(latency > my_hist->max_lat ||
+ my_hist->min_lat == LONG_MAX)) {
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST) ||
+ IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ if (latency_type == WAKEUP_LATENCY ||
+ latency_type == WAKEUP_LATENCY_SHAREDPRIO ||
+ latency_type == MISSED_TIMER_OFFSETS ||
+ latency_type == TIMERANDWAKEUP_LATENCY) {
+ strncpy(mp->comm, p->comm, sizeof(mp->comm));
+ strncpy(mp->current_comm, current->comm,
+ sizeof(mp->current_comm));
+ mp->pid = task_pid_nr(p);
+ mp->current_pid = task_pid_nr(current);
+ mp->prio = p->prio;
+ mp->current_prio = current->prio;
+ mp->latency = latency;
+ mp->timeroffset = timeroffset;
+ mp->timestamp = stop;
+ }
+ }
+ my_hist->max_lat = latency;
+ }
+ if (unlikely(latency < my_hist->min_lat))
+ my_hist->min_lat = latency;
+ my_hist->total_samples++;
+ my_hist->accumulate_lat += latency;
+}
+
+static void *l_start(struct seq_file *m, loff_t *pos)
+{
+ loff_t *index_ptr = NULL;
+ loff_t index = *pos;
+ struct hist_data *my_hist = m->private;
+
+ if (index == 0) {
+ char minstr[32], avgstr[32], maxstr[32];
+
+ atomic_dec(&my_hist->hist_mode);
+
+ if (likely(my_hist->total_samples)) {
+ long avg = (long) div64_s64(my_hist->accumulate_lat,
+ my_hist->total_samples);
+ snprintf(minstr, sizeof(minstr), "%ld",
+ my_hist->min_lat - my_hist->offset);
+ snprintf(avgstr, sizeof(avgstr), "%ld",
+ avg - my_hist->offset);
+ snprintf(maxstr, sizeof(maxstr), "%ld",
+ my_hist->max_lat - my_hist->offset);
+ } else {
+ strcpy(minstr, "<undef>");
+ strcpy(avgstr, minstr);
+ strcpy(maxstr, minstr);
+ }
+
+ seq_printf(m, "#Minimum latency: %s microseconds\n"
+ "#Average latency: %s microseconds\n"
+ "#Maximum latency: %s microseconds\n"
+ "#Total samples: %llu\n"
+ "#There are %llu samples lower than %ld"
+ " microseconds.\n"
+ "#There are %llu samples greater or equal"
+ " than %ld microseconds.\n"
+ "#usecs\t%16s\n",
+ minstr, avgstr, maxstr,
+ my_hist->total_samples,
+ my_hist->below_hist_bound_samples,
+ -my_hist->offset,
+ my_hist->above_hist_bound_samples,
+ MAX_ENTRY_NUM - my_hist->offset,
+ "samples");
+ }
+ if (index < MAX_ENTRY_NUM) {
+ index_ptr = kmalloc(sizeof(loff_t), GFP_KERNEL);
+ if (index_ptr)
+ *index_ptr = index;
+ }
+
+ return index_ptr;
+}
+
+static void *l_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ loff_t *index_ptr = p;
+ struct hist_data *my_hist = m->private;
+
+ if (++*pos >= MAX_ENTRY_NUM) {
+ atomic_inc(&my_hist->hist_mode);
+ return NULL;
+ }
+ *index_ptr = *pos;
+ return index_ptr;
+}
+
+static void l_stop(struct seq_file *m, void *p)
+{
+ kfree(p);
+}
+
+static int l_show(struct seq_file *m, void *p)
+{
+ int index = *(loff_t *) p;
+ struct hist_data *my_hist = m->private;
+
+ seq_printf(m, "%6ld\t%16llu\n", index - my_hist->offset,
+ my_hist->hist_array[index]);
+ return 0;
+}
+
+static const struct seq_operations latency_hist_seq_op = {
+ .start = l_start,
+ .next = l_next,
+ .stop = l_stop,
+ .show = l_show
+};
+
+static int latency_hist_open(struct inode *inode, struct file *file)
+{
+ int ret;
+
+ ret = seq_open(file, &latency_hist_seq_op);
+ if (!ret) {
+ struct seq_file *seq = file->private_data;
+
+ seq->private = inode->i_private;
+ }
+ return ret;
+}
+
+static const struct file_operations latency_hist_fops = {
+ .open = latency_hist_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+void clear_maxlatprocdata(struct maxlatproc_data *mp)
+{
+ mp->comm[0] = mp->current_comm[0] = '\0';
+ mp->prio = mp->current_prio = mp->pid = mp->current_pid =
+ mp->latency = mp->timeroffset = -1;
+ mp->timestamp = 0;
+}
+
+static void hist_reset(struct hist_data *hist)
+{
+ atomic_dec(&hist->hist_mode);
+
+ memset(hist->hist_array, 0, sizeof(hist->hist_array));
+ hist->below_hist_bound_samples = 0ULL;
+ hist->above_hist_bound_samples = 0ULL;
+ hist->min_lat = LONG_MAX;
+ hist->max_lat = LONG_MIN;
+ hist->total_samples = 0ULL;
+ hist->accumulate_lat = 0LL;
+
+ atomic_inc(&hist->hist_mode);
+}
+
+static ssize_t
+latency_hist_reset(struct file *file, const char __user *a,
+ size_t size, loff_t *off)
+{
+ int cpu;
+ struct hist_data *hist = NULL;
+ struct maxlatproc_data *mp __maybe_unused = NULL;
+ off_t latency_type = (off_t) file->private_data;
+
+ for_each_online_cpu(cpu) {
+
+ switch (latency_type) {
+ case PREEMPTOFF_LATENCY:
+ hist = &per_cpu(preemptoff_hist, cpu);
+ break;
+ case IRQSOFF_LATENCY:
+ hist = &per_cpu(irqsoff_hist, cpu);
+ break;
+ case PREEMPTIRQSOFF_LATENCY:
+ hist = &per_cpu(preemptirqsoff_hist, cpu);
+ break;
+ case WAKEUP_LATENCY:
+ hist = &per_cpu(wakeup_latency_hist, cpu);
+ mp = &per_cpu(wakeup_maxlatproc, cpu);
+ break;
+ case WAKEUP_LATENCY_SHAREDPRIO:
+ hist = &per_cpu(wakeup_latency_hist_sharedprio, cpu);
+ mp = &per_cpu(wakeup_maxlatproc_sharedprio, cpu);
+ break;
+ case MISSED_TIMER_OFFSETS:
+ hist = &per_cpu(missed_timer_offsets, cpu);
+ mp = &per_cpu(missed_timer_offsets_maxlatproc, cpu);
+ break;
+ case TIMERANDWAKEUP_LATENCY:
+ hist = &per_cpu(timerandwakeup_latency_hist, cpu);
+ mp = &per_cpu(timerandwakeup_maxlatproc, cpu);
+ break;
+ }
+
+ hist_reset(hist);
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST) ||
+ IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ if (latency_type == WAKEUP_LATENCY ||
+ latency_type == WAKEUP_LATENCY_SHAREDPRIO ||
+ latency_type == MISSED_TIMER_OFFSETS ||
+ latency_type == TIMERANDWAKEUP_LATENCY)
+ clear_maxlatprocdata(mp);
+ }
+ }
+ return size;
+}
+
+ssize_t
+show_pid(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+ int r;
+ unsigned long *this_pid = file->private_data;
+
+ r = snprintf(buf, sizeof(buf), "%lu\n", *this_pid);
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t do_pid(struct file *file, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+ unsigned long pid;
+ unsigned long *this_pid = file->private_data;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = '\0';
+
+ if (kstrtoul(buf, 10, &pid))
+ return -EINVAL;
+
+ *this_pid = pid;
+
+ return cnt;
+}
+
+ssize_t
+show_maxlatproc(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ int r;
+ struct maxlatproc_data *mp = file->private_data;
+ int strmaxlen = (TASK_COMM_LEN * 2) + (8 * 8);
+ unsigned long long t;
+ unsigned long usecs, secs;
+ char *buf;
+
+ if (mp->pid == -1 || mp->current_pid == -1) {
+ buf = "(none)\n";
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf,
+ strlen(buf));
+ }
+
+ buf = kmalloc(strmaxlen, GFP_KERNEL);
+ if (buf == NULL)
+ return -ENOMEM;
+
+ t = ns2usecs(mp->timestamp);
+ usecs = do_div(t, USEC_PER_SEC);
+ secs = (unsigned long) t;
+ r = snprintf(buf, strmaxlen,
+ "%d %d %ld (%ld) %s <- %d %d %s %lu.%06lu\n", mp->pid,
+ MAX_RT_PRIO-1 - mp->prio, mp->latency, mp->timeroffset, mp->comm,
+ mp->current_pid, MAX_RT_PRIO-1 - mp->current_prio, mp->current_comm,
+ secs, usecs);
+ r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+ kfree(buf);
+ return r;
+}
+
+static ssize_t
+show_enable(struct file *file, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+ struct enable_data *ed = file->private_data;
+ int r;
+
+ r = snprintf(buf, sizeof(buf), "%d\n", ed->enabled);
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t __maybe_unused enable_trace_events(struct enable_data *ed)
+{
+ int ret = 0;
+
+ switch (ed->latency_type) {
+ case PREEMPTIRQSOFF_LATENCY:
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST) ||
+ IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ ret = register_trace_preemptirqsoff_hist(
+ probe_preemptirqsoff_hist, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't assign"
+ " probe_preemptirqsoff_hist"
+ " to trace_preemptirqsoff_hist\n");
+ return ret;
+ }
+ }
+ break;
+
+ case WAKEUP_LATENCY:
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST)) {
+ ret = register_trace_sched_wakeup(
+ probe_wakeup_latency_hist_start, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't assign"
+ " probe_wakeup_latency_hist_start"
+ " to trace_sched_wakeup\n");
+ return ret;
+ }
+ ret = register_trace_sched_wakeup_new(
+ probe_wakeup_latency_hist_start, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't assign"
+ " probe_wakeup_latency_hist_start "
+ " to trace_sched_wakeup_new\n");
+ unregister_trace_sched_wakeup(
+ probe_wakeup_latency_hist_start,
+ NULL);
+ return ret;
+ }
+ ret = register_trace_sched_switch(
+ probe_wakeup_latency_hist_stop, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't assign"
+ " probe_wakeup_latency_hist_stop"
+ " to trace_sched_switch\n");
+ unregister_trace_sched_wakeup(
+ probe_wakeup_latency_hist_start,
+ NULL);
+ unregister_trace_sched_wakeup_new(
+ probe_wakeup_latency_hist_start,
+ NULL);
+ return ret;
+ }
+ ret = register_trace_sched_migrate_task(
+ probe_sched_migrate_task, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't assign"
+ " probe_sched_migrate_task"
+ " to trace_sched_migrate_task\n");
+ unregister_trace_sched_wakeup(
+ probe_wakeup_latency_hist_start,
+ NULL);
+ unregister_trace_sched_wakeup_new(
+ probe_wakeup_latency_hist_start,
+ NULL);
+ unregister_trace_sched_switch(
+ probe_wakeup_latency_hist_stop,
+ NULL);
+ return ret;
+ }
+ }
+ break;
+ case MISSED_TIMER_OFFSETS:
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ ret = register_trace_hrtimer_interrupt(
+ probe_hrtimer_interrupt, NULL);
+ if (ret) {
+ pr_info("wakeup trace: Couldn't assign "
+ "probe_hrtimer_interrupt "
+ "to trace_hrtimer_interrupt\n");
+ return ret;
+ }
+ }
+ break;
+ case TIMERANDWAKEUP_LATENCY:
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST) &&
+ IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ if (!wakeup_latency_enabled_data.enabled ||
+ !missed_timer_offsets_enabled_data.enabled)
+ return -EINVAL;
+ }
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+static void __maybe_unused disable_trace_events(struct enable_data *ed)
+{
+ switch (ed->latency_type) {
+ case PREEMPTIRQSOFF_LATENCY:
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST) ||
+ IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ int cpu;
+
+ unregister_trace_preemptirqsoff_hist(
+ probe_preemptirqsoff_hist, NULL);
+ for_each_online_cpu(cpu) {
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST))
+ per_cpu(hist_irqsoff_counting,
+ cpu) = 0;
+ if (IS_ENABLED(CONFIG_PREEMPT_OFF_HIST))
+ per_cpu(hist_preemptoff_counting,
+ cpu) = 0;
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST) &&
+ IS_ENABLED(CONFIG_PREEMPT_OFF_HIST))
+ per_cpu(hist_preemptirqsoff_counting,
+ cpu) = 0;
+ }
+ }
+ break;
+
+ case WAKEUP_LATENCY:
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST)) {
+ int cpu;
+
+ unregister_trace_sched_wakeup(
+ probe_wakeup_latency_hist_start, NULL);
+ unregister_trace_sched_wakeup_new(
+ probe_wakeup_latency_hist_start, NULL);
+ unregister_trace_sched_switch(
+ probe_wakeup_latency_hist_stop, NULL);
+ unregister_trace_sched_migrate_task(
+ probe_sched_migrate_task, NULL);
+
+ for_each_online_cpu(cpu) {
+ per_cpu(wakeup_task, cpu) = NULL;
+ per_cpu(wakeup_sharedprio, cpu) = 0;
+ }
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST))
+ timerandwakeup_enabled_data.enabled = 0;
+ }
+ break;
+
+ case MISSED_TIMER_OFFSETS:
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ unregister_trace_hrtimer_interrupt(
+ probe_hrtimer_interrupt, NULL);
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST))
+ timerandwakeup_enabled_data.enabled = 0;
+ }
+ break;
+ default:
+ break;
+ }
+}
+
+static ssize_t __maybe_unused
+do_enable(struct file *file, const char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+ long enable;
+ int ret;
+ struct enable_data *ed = file->private_data;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ if (kstrtoul(buf, 10, &enable))
+ return -EINVAL;
+
+ if ((enable && ed->enabled) || (!enable && !ed->enabled))
+ return cnt;
+
+ if (enable) {
+ ret = enable_trace_events(ed);
+ if (ret)
+ return ret;
+ } else {
+ disable_trace_events(ed);
+ }
+ ed->enabled = enable;
+ return cnt;
+}
+
+static const struct file_operations latency_hist_reset_fops = {
+ .open = tracing_open_generic,
+ .write = latency_hist_reset,
+};
+
+static const struct file_operations enable_fops = {
+ .open = tracing_open_generic,
+ .read = show_enable,
+ .write = do_enable,
+};
+
+static const struct file_operations __maybe_unused pid_fops = {
+ .open = tracing_open_generic,
+ .read = show_pid,
+ .write = do_pid,
+};
+
+static const struct file_operations __maybe_unused maxlatproc_fops = {
+ .open = tracing_open_generic,
+ .read = show_maxlatproc,
+};
+
+notrace void probe_preemptirqsoff_hist(void *v, int reason,
+ int starthist)
+{
+ int cpu = raw_smp_processor_id();
+ int time_set = 0;
+
+ if (starthist) {
+ cycle_t uninitialized_var(start);
+
+ if (!preempt_count() && !irqs_disabled())
+ return;
+
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST)) {
+ if ((reason == IRQS_OFF || reason == TRACE_START) &&
+ !per_cpu(hist_irqsoff_counting, cpu)) {
+ per_cpu(hist_irqsoff_counting, cpu) = 1;
+ start = ftrace_now(cpu);
+ time_set++;
+ per_cpu(hist_irqsoff_start, cpu) = start;
+ }
+ }
+
+ if (IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ if ((reason == PREEMPT_OFF || reason == TRACE_START) &&
+ !per_cpu(hist_preemptoff_counting, cpu)) {
+ per_cpu(hist_preemptoff_counting, cpu) = 1;
+ if (!(time_set++))
+ start = ftrace_now(cpu);
+ per_cpu(hist_preemptoff_start, cpu) = start;
+ }
+ }
+
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST) &&
+ IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ if (per_cpu(hist_irqsoff_counting, cpu) &&
+ per_cpu(hist_preemptoff_counting, cpu) &&
+ !per_cpu(hist_preemptirqsoff_counting, cpu)) {
+ per_cpu(hist_preemptirqsoff_counting, cpu) = 1;
+ if (!time_set)
+ start = ftrace_now(cpu);
+ per_cpu(hist_preemptirqsoff_start, cpu) = start;
+ }
+ }
+ } else {
+ cycle_t uninitialized_var(stop);
+
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST)) {
+ if ((reason == IRQS_ON || reason == TRACE_STOP) &&
+ per_cpu(hist_irqsoff_counting, cpu)) {
+ cycle_t start = per_cpu(hist_irqsoff_start,
+ cpu);
+
+ stop = ftrace_now(cpu);
+ time_set++;
+ if (start) {
+ long latency = ((long) (stop - start))
+ / NSECS_PER_USECS;
+
+ latency_hist(IRQSOFF_LATENCY, cpu,
+ latency, 0, stop, NULL);
+ }
+ per_cpu(hist_irqsoff_counting, cpu) = 0;
+ }
+ }
+
+ if (IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ if ((reason == PREEMPT_ON || reason == TRACE_STOP) &&
+ per_cpu(hist_preemptoff_counting, cpu)) {
+ cycle_t start = per_cpu(hist_preemptoff_start,
+ cpu);
+
+ if (!(time_set++))
+ stop = ftrace_now(cpu);
+ if (start) {
+ long latency = ((long) (stop - start))
+ / NSECS_PER_USECS;
+
+ latency_hist(PREEMPTOFF_LATENCY, cpu,
+ latency, 0, stop, NULL);
+ }
+ per_cpu(hist_preemptoff_counting, cpu) = 0;
+ }
+ }
+
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST) &&
+ IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ if ((!per_cpu(hist_irqsoff_counting, cpu) ||
+ !per_cpu(hist_preemptoff_counting, cpu)) &&
+ per_cpu(hist_preemptirqsoff_counting, cpu)) {
+ cycle_t start = per_cpu(
+ hist_preemptirqsoff_start,
+ cpu);
+
+ if (!time_set)
+ stop = ftrace_now(cpu);
+ if (start) {
+ long latency = ((long) (stop - start)) /
+ NSECS_PER_USECS;
+
+ latency_hist(PREEMPTIRQSOFF_LATENCY,
+ cpu, latency, 0, stop, NULL);
+ }
+ per_cpu(hist_preemptirqsoff_counting, cpu) = 0;
+ }
+ }
+ }
+}
+
+static DEFINE_RAW_SPINLOCK(wakeup_lock);
+notrace void probe_sched_migrate_task(void *v, struct task_struct *task,
+ int cpu)
+{
+ int old_cpu = task_cpu(task);
+
+ if (cpu != old_cpu) {
+ unsigned long flags;
+ struct task_struct *cpu_wakeup_task;
+
+ raw_spin_lock_irqsave(&wakeup_lock, flags);
+
+ cpu_wakeup_task = per_cpu(wakeup_task, old_cpu);
+ if (task == cpu_wakeup_task) {
+ put_task_struct(cpu_wakeup_task);
+ per_cpu(wakeup_task, old_cpu) = NULL;
+ cpu_wakeup_task = per_cpu(wakeup_task, cpu) = task;
+ get_task_struct(cpu_wakeup_task);
+ }
+
+ raw_spin_unlock_irqrestore(&wakeup_lock, flags);
+ }
+}
+
+notrace void probe_wakeup_latency_hist_start(void *v, struct task_struct *p)
+{
+ unsigned long flags;
+ struct task_struct *curr = current;
+ int cpu = task_cpu(p);
+ struct task_struct *cpu_wakeup_task;
+
+ raw_spin_lock_irqsave(&wakeup_lock, flags);
+
+ cpu_wakeup_task = per_cpu(wakeup_task, cpu);
+
+ if (wakeup_pid) {
+ if ((cpu_wakeup_task && p->prio == cpu_wakeup_task->prio) ||
+ p->prio == curr->prio)
+ per_cpu(wakeup_sharedprio, cpu) = 1;
+ if (likely(wakeup_pid != task_pid_nr(p)))
+ goto out;
+ } else {
+ if (likely(!rt_task(p)) ||
+ (cpu_wakeup_task && p->prio > cpu_wakeup_task->prio) ||
+ p->prio > curr->prio)
+ goto out;
+ if ((cpu_wakeup_task && p->prio == cpu_wakeup_task->prio) ||
+ p->prio == curr->prio)
+ per_cpu(wakeup_sharedprio, cpu) = 1;
+ }
+
+ if (cpu_wakeup_task)
+ put_task_struct(cpu_wakeup_task);
+ cpu_wakeup_task = per_cpu(wakeup_task, cpu) = p;
+ get_task_struct(cpu_wakeup_task);
+ cpu_wakeup_task->preempt_timestamp_hist =
+ ftrace_now(raw_smp_processor_id());
+out:
+ raw_spin_unlock_irqrestore(&wakeup_lock, flags);
+}
+
+notrace void probe_wakeup_latency_hist_stop(void *v, bool preempt,
+ struct task_struct *prev, struct task_struct *next)
+{
+ unsigned long flags;
+ int cpu = task_cpu(next);
+ long latency;
+ cycle_t stop;
+ struct task_struct *cpu_wakeup_task;
+
+ raw_spin_lock_irqsave(&wakeup_lock, flags);
+
+ cpu_wakeup_task = per_cpu(wakeup_task, cpu);
+
+ if (cpu_wakeup_task == NULL)
+ goto out;
+
+ /* Already running? */
+ if (unlikely(current == cpu_wakeup_task))
+ goto out_reset;
+
+ if (next != cpu_wakeup_task) {
+ if (next->prio < cpu_wakeup_task->prio)
+ goto out_reset;
+
+ if (next->prio == cpu_wakeup_task->prio)
+ per_cpu(wakeup_sharedprio, cpu) = 1;
+
+ goto out;
+ }
+
+ if (current->prio == cpu_wakeup_task->prio)
+ per_cpu(wakeup_sharedprio, cpu) = 1;
+
+ /*
+ * The task we are waiting for is about to be switched to.
+ * Calculate latency and store it in histogram.
+ */
+ stop = ftrace_now(raw_smp_processor_id());
+
+ latency = ((long) (stop - next->preempt_timestamp_hist)) /
+ NSECS_PER_USECS;
+
+ if (per_cpu(wakeup_sharedprio, cpu)) {
+ latency_hist(WAKEUP_LATENCY_SHAREDPRIO, cpu, latency, 0, stop,
+ next);
+ per_cpu(wakeup_sharedprio, cpu) = 0;
+ } else {
+ latency_hist(WAKEUP_LATENCY, cpu, latency, 0, stop, next);
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ if (timerandwakeup_enabled_data.enabled) {
+ latency_hist(TIMERANDWAKEUP_LATENCY, cpu,
+ next->timer_offset + latency,
+ next->timer_offset,
+ stop, next);
+ }
+ }
+ }
+
+out_reset:
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST))
+ next->timer_offset = 0;
+ put_task_struct(cpu_wakeup_task);
+ per_cpu(wakeup_task, cpu) = NULL;
+out:
+ raw_spin_unlock_irqrestore(&wakeup_lock, flags);
+}
+
+notrace void probe_hrtimer_interrupt(void *v, int cpu,
+ long long latency_ns, struct task_struct *curr,
+ struct task_struct *task)
+{
+ if (latency_ns <= 0 && task != NULL && rt_task(task) &&
+ (task->prio < curr->prio ||
+ (task->prio == curr->prio &&
+ !cpumask_test_cpu(cpu, &task->cpus_allowed)))) {
+ long latency;
+ cycle_t now;
+
+ if (missed_timer_offsets_pid) {
+ if (likely(missed_timer_offsets_pid !=
+ task_pid_nr(task)))
+ return;
+ }
+
+ now = ftrace_now(cpu);
+ latency = (long) div_s64(-latency_ns, NSECS_PER_USECS);
+ latency_hist(MISSED_TIMER_OFFSETS, cpu, latency, latency, now,
+ task);
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST))
+ task->timer_offset = latency;
+ }
+}
+
+static __init int latency_hist_init(void)
+{
+ struct dentry *latency_hist_root = NULL;
+ struct dentry *dentry;
+ struct dentry *dentry_sharedprio __maybe_unused;
+ struct dentry *entry;
+ struct dentry *enable_root;
+ int i = 0;
+ struct hist_data *my_hist;
+ char name[64];
+ char *cpufmt = "CPU%d";
+ char *cpufmt_maxlatproc __maybe_unused = "max_latency-CPU%d";
+ struct maxlatproc_data *mp __maybe_unused = NULL;
+
+ dentry = tracing_init_dentry();
+ latency_hist_root = debugfs_create_dir(latency_hist_dir_root, dentry);
+ enable_root = debugfs_create_dir("enable", latency_hist_root);
+
+
+ if (IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST)) {
+ dentry = debugfs_create_dir(irqsoff_hist_dir,
+ latency_hist_root);
+ for_each_possible_cpu(i) {
+ sprintf(name, cpufmt, i);
+ entry = debugfs_create_file(name, 0444, dentry,
+ &per_cpu(irqsoff_hist, i), &latency_hist_fops);
+ my_hist = &per_cpu(irqsoff_hist, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+ }
+ entry = debugfs_create_file("reset", 0644, dentry,
+ (void *)IRQSOFF_LATENCY, &latency_hist_reset_fops);
+ }
+
+ if (IS_ENABLED(CONFIG_PREEMPT_OFF_HIST)) {
+ dentry = debugfs_create_dir(preemptoff_hist_dir,
+ latency_hist_root);
+ for_each_possible_cpu(i) {
+ sprintf(name, cpufmt, i);
+ entry = debugfs_create_file(name, 0444, dentry,
+ &per_cpu(preemptoff_hist, i), &latency_hist_fops);
+ my_hist = &per_cpu(preemptoff_hist, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+ }
+ entry = debugfs_create_file("reset", 0644, dentry,
+ (void *)PREEMPTOFF_LATENCY, &latency_hist_reset_fops);
+ }
+
+ if (IS_ENABLED(CONFIG_PREEMPT_OFF_HIST) &&
+ IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST)) {
+ dentry = debugfs_create_dir(preemptirqsoff_hist_dir,
+ latency_hist_root);
+ for_each_possible_cpu(i) {
+ sprintf(name, cpufmt, i);
+ entry = debugfs_create_file(name, 0444, dentry,
+ &per_cpu(preemptirqsoff_hist, i),
+ &latency_hist_fops);
+ my_hist = &per_cpu(preemptirqsoff_hist, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+ }
+ entry = debugfs_create_file("reset", 0644, dentry,
+ (void *)PREEMPTIRQSOFF_LATENCY, &latency_hist_reset_fops);
+
+ }
+
+ if (IS_ENABLED(CONFIG_PREEMPT_OFF_HIST) ||
+ IS_ENABLED(CONFIG_INTERRUPT_OFF_HIST)) {
+ entry = debugfs_create_file("preemptirqsoff", 0644,
+ enable_root, (void *)&preemptirqsoff_enabled_data,
+ &enable_fops);
+ }
+
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST)) {
+ dentry = debugfs_create_dir(wakeup_latency_hist_dir,
+ latency_hist_root);
+ dentry_sharedprio = debugfs_create_dir(
+ wakeup_latency_hist_dir_sharedprio, dentry);
+ for_each_possible_cpu(i) {
+ sprintf(name, cpufmt, i);
+
+ entry = debugfs_create_file(name, 0444, dentry,
+ &per_cpu(wakeup_latency_hist, i),
+ &latency_hist_fops);
+ my_hist = &per_cpu(wakeup_latency_hist, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+
+ entry = debugfs_create_file(name, 0444,
+ dentry_sharedprio,
+ &per_cpu(wakeup_latency_hist_sharedprio, i),
+ &latency_hist_fops);
+ my_hist = &per_cpu(wakeup_latency_hist_sharedprio, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+
+ sprintf(name, cpufmt_maxlatproc, i);
+
+ mp = &per_cpu(wakeup_maxlatproc, i);
+ entry = debugfs_create_file(name, 0444, dentry, mp,
+ &maxlatproc_fops);
+ clear_maxlatprocdata(mp);
+
+ mp = &per_cpu(wakeup_maxlatproc_sharedprio, i);
+ entry = debugfs_create_file(name, 0444,
+ dentry_sharedprio, mp, &maxlatproc_fops);
+ clear_maxlatprocdata(mp);
+ }
+ entry = debugfs_create_file("pid", 0644, dentry,
+ (void *)&wakeup_pid, &pid_fops);
+ entry = debugfs_create_file("reset", 0644, dentry,
+ (void *)WAKEUP_LATENCY, &latency_hist_reset_fops);
+ entry = debugfs_create_file("reset", 0644, dentry_sharedprio,
+ (void *)WAKEUP_LATENCY_SHAREDPRIO,
+ &latency_hist_reset_fops);
+ entry = debugfs_create_file("wakeup", 0644,
+ enable_root, (void *)&wakeup_latency_enabled_data,
+ &enable_fops);
+ }
+
+ if (IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ dentry = debugfs_create_dir(missed_timer_offsets_dir,
+ latency_hist_root);
+ for_each_possible_cpu(i) {
+ sprintf(name, cpufmt, i);
+ entry = debugfs_create_file(name, 0444, dentry,
+ &per_cpu(missed_timer_offsets, i),
+ &latency_hist_fops);
+ my_hist = &per_cpu(missed_timer_offsets, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+
+ sprintf(name, cpufmt_maxlatproc, i);
+ mp = &per_cpu(missed_timer_offsets_maxlatproc, i);
+ entry = debugfs_create_file(name, 0444, dentry, mp,
+ &maxlatproc_fops);
+ clear_maxlatprocdata(mp);
+ }
+ entry = debugfs_create_file("pid", 0644, dentry,
+ (void *)&missed_timer_offsets_pid, &pid_fops);
+ entry = debugfs_create_file("reset", 0644, dentry,
+ (void *)MISSED_TIMER_OFFSETS, &latency_hist_reset_fops);
+ entry = debugfs_create_file("missed_timer_offsets", 0644,
+ enable_root, (void *)&missed_timer_offsets_enabled_data,
+ &enable_fops);
+ }
+
+ if (IS_ENABLED(CONFIG_WAKEUP_LATENCY_HIST) ||
+ IS_ENABLED(CONFIG_MISSED_TIMER_OFFSETS_HIST)) {
+ dentry = debugfs_create_dir(timerandwakeup_latency_hist_dir,
+ latency_hist_root);
+ for_each_possible_cpu(i) {
+ sprintf(name, cpufmt, i);
+ entry = debugfs_create_file(name, 0444, dentry,
+ &per_cpu(timerandwakeup_latency_hist, i),
+ &latency_hist_fops);
+ my_hist = &per_cpu(timerandwakeup_latency_hist, i);
+ atomic_set(&my_hist->hist_mode, 1);
+ my_hist->min_lat = LONG_MAX;
+
+ sprintf(name, cpufmt_maxlatproc, i);
+ mp = &per_cpu(timerandwakeup_maxlatproc, i);
+ entry = debugfs_create_file(name, 0444, dentry, mp,
+ &maxlatproc_fops);
+ clear_maxlatprocdata(mp);
+ }
+ entry = debugfs_create_file("reset", 0644, dentry,
+ (void *)TIMERANDWAKEUP_LATENCY, &latency_hist_reset_fops);
+ entry = debugfs_create_file("timerandwakeup", 0644,
+ enable_root, (void *)&timerandwakeup_enabled_data,
+ &enable_fops);
+ }
+ return 0;
+}
+
+device_initcall(latency_hist_init);
+
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 03cdff8..e138d69 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -13,6 +13,7 @@
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ftrace.h>
+#include <trace/events/hist.h>
#include "trace.h"
@@ -424,11 +425,13 @@ void start_critical_timings(void)
{
if (preempt_trace() || irq_trace())
start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+ trace_preemptirqsoff_hist(TRACE_START, 1);
}
EXPORT_SYMBOL_GPL(start_critical_timings);
void stop_critical_timings(void)
{
+ trace_preemptirqsoff_hist(TRACE_STOP, 0);
if (preempt_trace() || irq_trace())
stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
}
@@ -438,6 +441,7 @@ EXPORT_SYMBOL_GPL(stop_critical_timings);
#ifdef CONFIG_PROVE_LOCKING
void time_hardirqs_on(unsigned long a0, unsigned long a1)
{
+ trace_preemptirqsoff_hist(IRQS_ON, 0);
if (!preempt_trace() && irq_trace())
stop_critical_timing(a0, a1);
}
@@ -446,6 +450,7 @@ void time_hardirqs_off(unsigned long a0, unsigned long a1)
{
if (!preempt_trace() && irq_trace())
start_critical_timing(a0, a1);
+ trace_preemptirqsoff_hist(IRQS_OFF, 1);
}
#else /* !CONFIG_PROVE_LOCKING */
@@ -485,6 +490,7 @@ EXPORT_SYMBOL(trace_hardirqs_off);
__visible void trace_hardirqs_on_caller(unsigned long caller_addr)
{
+ trace_preemptirqsoff_hist(IRQS_ON, 0);
if (!preempt_trace() && irq_trace())
stop_critical_timing(CALLER_ADDR0, caller_addr);
}
@@ -494,6 +500,7 @@ __visible void trace_hardirqs_off_caller(unsigned long caller_addr)
{
if (!preempt_trace() && irq_trace())
start_critical_timing(CALLER_ADDR0, caller_addr);
+ trace_preemptirqsoff_hist(IRQS_OFF, 1);
}
EXPORT_SYMBOL(trace_hardirqs_off_caller);
@@ -503,12 +510,14 @@ EXPORT_SYMBOL(trace_hardirqs_off_caller);
#ifdef CONFIG_PREEMPT_TRACER
void trace_preempt_on(unsigned long a0, unsigned long a1)
{
+ trace_preemptirqsoff_hist(PREEMPT_ON, 0);
if (preempt_trace() && !irq_trace())
stop_critical_timing(a0, a1);
}
void trace_preempt_off(unsigned long a0, unsigned long a1)
{
+ trace_preemptirqsoff_hist(PREEMPT_ON, 1);
if (preempt_trace() && !irq_trace())
start_critical_timing(a0, a1);
}
--
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