latency-hist.patch

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. For details please consult Documentation/trace/histograms.txt.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

4 files changed, 1297 insertions, 0 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 015f85a..bbe95b9 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -192,6 +192,24 @@ 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
@@ -216,6 +234,24 @@ 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
@@ -226,6 +262,74 @@ 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 d7e2068..f5e0243 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -34,6 +34,10 @@ 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..66a69eb
--- /dev/null
+++ b/kernel/trace/latency_hist.c
@@ -0,0 +1,1178 @@
+/*
+ * 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@ch.mvista.com>
+ *
+ *  Converted to work with the new latency tracer.
+ *  Copyright (C) 2008 Red Hat, Inc.
+ *    Steven Rostedt <srostedt@redhat.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>
+
+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;
+};
+
+static char *latency_hist_dir_root = "latency_hist";
+
+#ifdef CONFIG_INTERRUPT_OFF_HIST
+static DEFINE_PER_CPU(struct hist_data, irqsoff_hist);
+static char *irqsoff_hist_dir = "irqsoff";
+static DEFINE_PER_CPU(cycles_t, hist_irqsoff_start);
+static DEFINE_PER_CPU(int, hist_irqsoff_counting);
+#endif
+
+#ifdef CONFIG_PREEMPT_OFF_HIST
+static DEFINE_PER_CPU(struct hist_data, preemptoff_hist);
+static char *preemptoff_hist_dir = "preemptoff";
+static DEFINE_PER_CPU(cycles_t, hist_preemptoff_start);
+static DEFINE_PER_CPU(int, hist_preemptoff_counting);
+#endif
+
+#if defined(CONFIG_PREEMPT_OFF_HIST) && defined(CONFIG_INTERRUPT_OFF_HIST)
+static DEFINE_PER_CPU(struct hist_data, preemptirqsoff_hist);
+static char *preemptirqsoff_hist_dir = "preemptirqsoff";
+static DEFINE_PER_CPU(cycles_t, hist_preemptirqsoff_start);
+static DEFINE_PER_CPU(int, hist_preemptirqsoff_counting);
+#endif
+
+#if defined(CONFIG_PREEMPT_OFF_HIST) || defined(CONFIG_INTERRUPT_OFF_HIST)
+static notrace void probe_preemptirqsoff_hist(void *v, int reason, int start);
+static struct enable_data preemptirqsoff_enabled_data = {
+	.latency_type = PREEMPTIRQSOFF_LATENCY,
+	.enabled = 0,
+};
+#endif
+
+#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;
+};
+#endif
+
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+static DEFINE_PER_CPU(struct hist_data, wakeup_latency_hist);
+static DEFINE_PER_CPU(struct hist_data, wakeup_latency_hist_sharedprio);
+static char *wakeup_latency_hist_dir = "wakeup";
+static char *wakeup_latency_hist_dir_sharedprio = "sharedprio";
+static notrace void probe_wakeup_latency_hist_start(void *v,
+	struct task_struct *p, int success);
+static notrace void probe_wakeup_latency_hist_stop(void *v,
+	struct task_struct *prev, struct task_struct *next);
+static notrace void probe_sched_migrate_task(void *,
+	struct task_struct *task, int cpu);
+static struct enable_data 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;
+#endif
+
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+static DEFINE_PER_CPU(struct hist_data, missed_timer_offsets);
+static char *missed_timer_offsets_dir = "missed_timer_offsets";
+static notrace void probe_hrtimer_interrupt(void *v, int cpu,
+	long long offset, struct task_struct *curr, struct task_struct *task);
+static struct enable_data missed_timer_offsets_enabled_data = {
+	.latency_type = MISSED_TIMER_OFFSETS,
+	.enabled = 0,
+};
+static DEFINE_PER_CPU(struct maxlatproc_data, missed_timer_offsets_maxlatproc);
+static unsigned long missed_timer_offsets_pid;
+#endif
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) && \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+static DEFINE_PER_CPU(struct hist_data, timerandwakeup_latency_hist);
+static char *timerandwakeup_latency_hist_dir = "timerandwakeup";
+static struct enable_data timerandwakeup_enabled_data = {
+	.latency_type = TIMERANDWAKEUP_LATENCY,
+	.enabled = 0,
+};
+static DEFINE_PER_CPU(struct maxlatproc_data, timerandwakeup_maxlatproc);
+#endif
+
+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;
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+	struct maxlatproc_data *mp = NULL;
+#endif
+
+	if (!cpu_possible(cpu) || latency_type < 0 ||
+	    latency_type >= MAX_LATENCY_TYPE)
+		return;
+
+	switch (latency_type) {
+#ifdef CONFIG_INTERRUPT_OFF_HIST
+	case IRQSOFF_LATENCY:
+		my_hist = &per_cpu(irqsoff_hist, cpu);
+		break;
+#endif
+#ifdef CONFIG_PREEMPT_OFF_HIST
+	case PREEMPTOFF_LATENCY:
+		my_hist = &per_cpu(preemptoff_hist, cpu);
+		break;
+#endif
+#if defined(CONFIG_PREEMPT_OFF_HIST) && defined(CONFIG_INTERRUPT_OFF_HIST)
+	case PREEMPTIRQSOFF_LATENCY:
+		my_hist = &per_cpu(preemptirqsoff_hist, cpu);
+		break;
+#endif
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+	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;
+#endif
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+	case MISSED_TIMER_OFFSETS:
+		my_hist = &per_cpu(missed_timer_offsets, cpu);
+		mp = &per_cpu(missed_timer_offsets_maxlatproc, cpu);
+		break;
+#endif
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) && \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+	case TIMERANDWAKEUP_LATENCY:
+		my_hist = &per_cpu(timerandwakeup_latency_hist, cpu);
+		mp = &per_cpu(timerandwakeup_maxlatproc, cpu);
+		break;
+#endif
+
+	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 defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(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;
+		}
+#endif
+		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,
+};
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+static 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;
+}
+#endif
+
+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;
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+	struct maxlatproc_data *mp = NULL;
+#endif
+	off_t latency_type = (off_t) file->private_data;
+
+	for_each_online_cpu(cpu) {
+
+		switch (latency_type) {
+#ifdef CONFIG_PREEMPT_OFF_HIST
+		case PREEMPTOFF_LATENCY:
+			hist = &per_cpu(preemptoff_hist, cpu);
+			break;
+#endif
+#ifdef CONFIG_INTERRUPT_OFF_HIST
+		case IRQSOFF_LATENCY:
+			hist = &per_cpu(irqsoff_hist, cpu);
+			break;
+#endif
+#if defined(CONFIG_INTERRUPT_OFF_HIST) && defined(CONFIG_PREEMPT_OFF_HIST)
+		case PREEMPTIRQSOFF_LATENCY:
+			hist = &per_cpu(preemptirqsoff_hist, cpu);
+			break;
+#endif
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+		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;
+#endif
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+		case MISSED_TIMER_OFFSETS:
+			hist = &per_cpu(missed_timer_offsets, cpu);
+			mp = &per_cpu(missed_timer_offsets_maxlatproc, cpu);
+			break;
+#endif
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) && \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+		case TIMERANDWAKEUP_LATENCY:
+			hist = &per_cpu(timerandwakeup_latency_hist, cpu);
+			mp = &per_cpu(timerandwakeup_maxlatproc, cpu);
+			break;
+#endif
+		}
+
+		hist_reset(hist);
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(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);
+#endif
+	}
+
+	return size;
+}
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+static 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;
+}
+#endif
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+static 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;
+}
+#endif
+
+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
+do_enable(struct file *file, const char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+	char buf[64];
+	long enable;
+	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) {
+		int ret;
+
+		switch (ed->latency_type) {
+#if defined(CONFIG_INTERRUPT_OFF_HIST) || defined(CONFIG_PREEMPT_OFF_HIST)
+		case PREEMPTIRQSOFF_LATENCY:
+			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;
+#endif
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+		case WAKEUP_LATENCY:
+			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;
+#endif
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+		case MISSED_TIMER_OFFSETS:
+			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;
+#endif
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) && \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+		case TIMERANDWAKEUP_LATENCY:
+			if (!wakeup_latency_enabled_data.enabled ||
+			    !missed_timer_offsets_enabled_data.enabled)
+				return -EINVAL;
+			break;
+#endif
+		default:
+			break;
+		}
+	} else {
+		switch (ed->latency_type) {
+#if defined(CONFIG_INTERRUPT_OFF_HIST) || defined(CONFIG_PREEMPT_OFF_HIST)
+		case PREEMPTIRQSOFF_LATENCY:
+			{
+				int cpu;
+
+				unregister_trace_preemptirqsoff_hist(
+				    probe_preemptirqsoff_hist, NULL);
+				for_each_online_cpu(cpu) {
+#ifdef CONFIG_INTERRUPT_OFF_HIST
+					per_cpu(hist_irqsoff_counting,
+					    cpu) = 0;
+#endif
+#ifdef CONFIG_PREEMPT_OFF_HIST
+					per_cpu(hist_preemptoff_counting,
+					    cpu) = 0;
+#endif
+#if defined(CONFIG_INTERRUPT_OFF_HIST) && defined(CONFIG_PREEMPT_OFF_HIST)
+					per_cpu(hist_preemptirqsoff_counting,
+					    cpu) = 0;
+#endif
+				}
+			}
+			break;
+#endif
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+		case WAKEUP_LATENCY:
+			{
+				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;
+				}
+			}
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+			timerandwakeup_enabled_data.enabled = 0;
+#endif
+			break;
+#endif
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+		case MISSED_TIMER_OFFSETS:
+			unregister_trace_hrtimer_interrupt(
+			    probe_hrtimer_interrupt, NULL);
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+			timerandwakeup_enabled_data.enabled = 0;
+#endif
+			break;
+#endif
+		default:
+			break;
+		}
+	}
+	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,
+};
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+static const struct file_operations pid_fops = {
+	.open = tracing_open_generic,
+	.read = show_pid,
+	.write = do_pid,
+};
+
+static const struct file_operations maxlatproc_fops = {
+	.open = tracing_open_generic,
+	.read = show_maxlatproc,
+};
+#endif
+
+#if defined(CONFIG_INTERRUPT_OFF_HIST) || defined(CONFIG_PREEMPT_OFF_HIST)
+static 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;
+
+#ifdef 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;
+		}
+#endif
+
+#ifdef 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;
+		}
+#endif
+
+#if defined(CONFIG_INTERRUPT_OFF_HIST) && defined(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;
+		}
+#endif
+	} else {
+		cycle_t uninitialized_var(stop);
+
+#ifdef 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;
+		}
+#endif
+
+#ifdef 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;
+		}
+#endif
+
+#if defined(CONFIG_INTERRUPT_OFF_HIST) && defined(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;
+		}
+#endif
+	}
+}
+#endif
+
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+static DEFINE_RAW_SPINLOCK(wakeup_lock);
+static 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);
+	}
+}
+
+static notrace void probe_wakeup_latency_hist_start(void *v,
+	struct task_struct *p, int success)
+{
+	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);
+}
+
+static notrace void probe_wakeup_latency_hist_stop(void *v,
+	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);
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+		if (timerandwakeup_enabled_data.enabled) {
+			latency_hist(TIMERANDWAKEUP_LATENCY, cpu,
+			    next->timer_offset + latency, next->timer_offset,
+			    stop, next);
+		}
+#endif
+	}
+
+out_reset:
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+	next->timer_offset = 0;
+#endif
+	put_task_struct(cpu_wakeup_task);
+	per_cpu(wakeup_task, cpu) = NULL;
+out:
+	raw_spin_unlock_irqrestore(&wakeup_lock, flags);
+}
+#endif
+
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+static 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);
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+		task->timer_offset = latency;
+#endif
+	}
+}
+#endif
+
+static __init int latency_hist_init(void)
+{
+	struct dentry *latency_hist_root = NULL;
+	struct dentry *dentry;
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+	struct dentry *dentry_sharedprio;
+#endif
+	struct dentry *entry;
+	struct dentry *enable_root;
+	int i = 0;
+	struct hist_data *my_hist;
+	char name[64];
+	char *cpufmt = "CPU%d";
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) || \
+	defined(CONFIG_MISSED_TIMER_OFFSETS_HIST)
+	char *cpufmt_maxlatproc = "max_latency-CPU%d";
+	struct maxlatproc_data *mp = NULL;
+#endif
+
+	dentry = tracing_init_dentry();
+	latency_hist_root = debugfs_create_dir(latency_hist_dir_root, dentry);
+	enable_root = debugfs_create_dir("enable", latency_hist_root);
+
+#ifdef 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);
+#endif
+
+#ifdef 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);
+#endif
+
+#if defined(CONFIG_INTERRUPT_OFF_HIST) && defined(CONFIG_PREEMPT_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);
+#endif
+
+#if defined(CONFIG_INTERRUPT_OFF_HIST) || defined(CONFIG_PREEMPT_OFF_HIST)
+	entry = debugfs_create_file("preemptirqsoff", 0644,
+	    enable_root, (void *)&preemptirqsoff_enabled_data,
+	    &enable_fops);
+#endif
+
+#ifdef 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);
+#endif
+
+#ifdef 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);
+#endif
+
+#if defined(CONFIG_WAKEUP_LATENCY_HIST) && \
+	defined(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);
+#endif
+	return 0;
+}
+
+device_initcall(latency_hist_init);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 2aefbee..2f4eb37 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 
 #include "trace.h"
+#include <trace/events/hist.h>
 
 static struct trace_array		*irqsoff_trace __read_mostly;
 static int				tracer_enabled __read_mostly;
@@ -439,11 +440,13 @@ 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);
 }
@@ -453,6 +456,7 @@ 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);
 }
@@ -461,6 +465,7 @@ 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 */
@@ -486,6 +491,7 @@ inline void print_irqtrace_events(struct task_struct *curr)
  */
 void trace_hardirqs_on(void)
 {
+	trace_preemptirqsoff_hist(IRQS_ON, 0);
 	if (!preempt_trace() && irq_trace())
 		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 }
@@ -495,11 +501,13 @@ void trace_hardirqs_off(void)
 {
 	if (!preempt_trace() && irq_trace())
 		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+	trace_preemptirqsoff_hist(IRQS_OFF, 1);
 }
 EXPORT_SYMBOL(trace_hardirqs_off);
 
 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);
 }
@@ -509,6 +517,7 @@ 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);
 
@@ -518,12 +527,14 @@ 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);
 }