Commit 9745512c authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Ingo Molnar

sched: latencytop support

LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 326587b8
......@@ -33,6 +33,19 @@ static void save_stack_address(void *data, unsigned long addr)
trace->entries[trace->nr_entries++] = addr;
}
static void save_stack_address_nosched(void *data, unsigned long addr)
{
struct stack_trace *trace = (struct stack_trace *)data;
if (in_sched_functions(addr))
return;
if (trace->skip > 0) {
trace->skip--;
return;
}
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = addr;
}
static const struct stacktrace_ops save_stack_ops = {
.warning = save_stack_warning,
.warning_symbol = save_stack_warning_symbol,
......@@ -40,6 +53,13 @@ static const struct stacktrace_ops save_stack_ops = {
.address = save_stack_address,
};
static const struct stacktrace_ops save_stack_ops_nosched = {
.warning = save_stack_warning,
.warning_symbol = save_stack_warning_symbol,
.stack = save_stack_stack,
.address = save_stack_address_nosched,
};
/*
* Save stack-backtrace addresses into a stack_trace buffer.
*/
......@@ -50,3 +70,10 @@ void save_stack_trace(struct stack_trace *trace)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}
EXPORT_SYMBOL(save_stack_trace);
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
dump_trace(tsk, NULL, NULL, &save_stack_ops_nosched, trace);
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}
......@@ -310,6 +310,77 @@ static int proc_pid_schedstat(struct task_struct *task, char *buffer)
}
#endif
#ifdef CONFIG_LATENCYTOP
static int lstats_show_proc(struct seq_file *m, void *v)
{
int i;
struct task_struct *task = m->private;
seq_puts(m, "Latency Top version : v0.1\n");
for (i = 0; i < 32; i++) {
if (task->latency_record[i].backtrace[0]) {
int q;
seq_printf(m, "%i %li %li ",
task->latency_record[i].count,
task->latency_record[i].time,
task->latency_record[i].max);
for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
char sym[KSYM_NAME_LEN];
char *c;
if (!task->latency_record[i].backtrace[q])
break;
if (task->latency_record[i].backtrace[q] == ULONG_MAX)
break;
sprint_symbol(sym, task->latency_record[i].backtrace[q]);
c = strchr(sym, '+');
if (c)
*c = 0;
seq_printf(m, "%s ", sym);
}
seq_printf(m, "\n");
}
}
return 0;
}
static int lstats_open(struct inode *inode, struct file *file)
{
int ret;
struct seq_file *m;
struct task_struct *task = get_proc_task(inode);
ret = single_open(file, lstats_show_proc, NULL);
if (!ret) {
m = file->private_data;
m->private = task;
}
return ret;
}
static ssize_t lstats_write(struct file *file, const char __user *buf,
size_t count, loff_t *offs)
{
struct seq_file *m;
struct task_struct *task;
m = file->private_data;
task = m->private;
clear_all_latency_tracing(task);
return count;
}
static const struct file_operations proc_lstats_operations = {
.open = lstats_open,
.read = seq_read,
.write = lstats_write,
.llseek = seq_lseek,
.release = single_release,
};
#endif
/* The badness from the OOM killer */
unsigned long badness(struct task_struct *p, unsigned long uptime);
static int proc_oom_score(struct task_struct *task, char *buffer)
......@@ -1020,6 +1091,7 @@ static const struct file_operations proc_fault_inject_operations = {
};
#endif
#ifdef CONFIG_SCHED_DEBUG
/*
* Print out various scheduling related per-task fields:
......@@ -2230,6 +2302,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, pid_schedstat),
#endif
#ifdef CONFIG_LATENCYTOP
REG("latency", S_IRUGO, lstats),
#endif
#ifdef CONFIG_PROC_PID_CPUSET
REG("cpuset", S_IRUGO, cpuset),
#endif
......@@ -2555,6 +2630,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, pid_schedstat),
#endif
#ifdef CONFIG_LATENCYTOP
REG("latency", S_IRUGO, lstats),
#endif
#ifdef CONFIG_PROC_PID_CPUSET
REG("cpuset", S_IRUGO, cpuset),
#endif
......
/*
* latencytop.h: Infrastructure for displaying latency
*
* (C) Copyright 2008 Intel Corporation
* Author: Arjan van de Ven <arjan@linux.intel.com>
*
*/
#ifndef _INCLUDE_GUARD_LATENCYTOP_H_
#define _INCLUDE_GUARD_LATENCYTOP_H_
#ifdef CONFIG_LATENCYTOP
#define LT_SAVECOUNT 32
#define LT_BACKTRACEDEPTH 12
struct latency_record {
unsigned long backtrace[LT_BACKTRACEDEPTH];
unsigned int count;
unsigned long time;
unsigned long max;
};
struct task_struct;
void account_scheduler_latency(struct task_struct *task, int usecs, int inter);
void clear_all_latency_tracing(struct task_struct *p);
#else
static inline void
account_scheduler_latency(struct task_struct *task, int usecs, int inter)
{
}
static inline void clear_all_latency_tracing(struct task_struct *p)
{
}
#endif
#endif
......@@ -88,6 +88,7 @@ struct sched_param {
#include <linux/hrtimer.h>
#include <linux/task_io_accounting.h>
#include <linux/kobject.h>
#include <linux/latencytop.h>
#include <asm/processor.h>
......@@ -1220,6 +1221,10 @@ struct task_struct {
int make_it_fail;
#endif
struct prop_local_single dirties;
#ifdef CONFIG_LATENCYTOP
int latency_record_count;
struct latency_record latency_record[LT_SAVECOUNT];
#endif
};
/*
......
......@@ -9,10 +9,13 @@ struct stack_trace {
};
extern void save_stack_trace(struct stack_trace *trace);
extern void save_stack_trace_tsk(struct task_struct *tsk,
struct stack_trace *trace);
extern void print_stack_trace(struct stack_trace *trace, int spaces);
#else
# define save_stack_trace(trace) do { } while (0)
# define save_stack_trace_tsk(tsk, trace) do { } while (0)
# define print_stack_trace(trace, spaces) do { } while (0)
#endif
......
......@@ -62,6 +62,7 @@ obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
obj-$(CONFIG_MARKERS) += marker.o
obj-$(CONFIG_LATENCYTOP) += latencytop.o
ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
......
......@@ -1205,6 +1205,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
clear_all_latency_tracing(p);
/* Our parent execution domain becomes current domain
These must match for thread signalling to apply */
......
/*
* latencytop.c: Latency display infrastructure
*
* (C) Copyright 2008 Intel Corporation
* Author: Arjan van de Ven <arjan@linux.intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#include <linux/latencytop.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
static DEFINE_SPINLOCK(latency_lock);
#define MAXLR 128
static struct latency_record latency_record[MAXLR];
int latencytop_enabled;
void clear_all_latency_tracing(struct task_struct *p)
{
unsigned long flags;
if (!latencytop_enabled)
return;
spin_lock_irqsave(&latency_lock, flags);
memset(&p->latency_record, 0, sizeof(p->latency_record));
p->latency_record_count = 0;
spin_unlock_irqrestore(&latency_lock, flags);
}
static void clear_global_latency_tracing(void)
{
unsigned long flags;
spin_lock_irqsave(&latency_lock, flags);
memset(&latency_record, 0, sizeof(latency_record));
spin_unlock_irqrestore(&latency_lock, flags);
}
static void __sched
account_global_scheduler_latency(struct task_struct *tsk, struct latency_record *lat)
{
int firstnonnull = MAXLR + 1;
int i;
if (!latencytop_enabled)
return;
/* skip kernel threads for now */
if (!tsk->mm)
return;
for (i = 0; i < MAXLR; i++) {
int q;
int same = 1;
/* Nothing stored: */
if (!latency_record[i].backtrace[0]) {
if (firstnonnull > i)
firstnonnull = i;
continue;
}
for (q = 0 ; q < LT_BACKTRACEDEPTH ; q++) {
if (latency_record[i].backtrace[q] !=
lat->backtrace[q])
same = 0;
if (same && lat->backtrace[q] == 0)
break;
if (same && lat->backtrace[q] == ULONG_MAX)
break;
}
if (same) {
latency_record[i].count++;
latency_record[i].time += lat->time;
if (lat->time > latency_record[i].max)
latency_record[i].max = lat->time;
return;
}
}
i = firstnonnull;
if (i >= MAXLR - 1)
return;
/* Allocted a new one: */
memcpy(&latency_record[i], lat, sizeof(struct latency_record));
}
static inline void store_stacktrace(struct task_struct *tsk, struct latency_record *lat)
{
struct stack_trace trace;
memset(&trace, 0, sizeof(trace));
trace.max_entries = LT_BACKTRACEDEPTH;
trace.entries = &lat->backtrace[0];
trace.skip = 0;
save_stack_trace_tsk(tsk, &trace);
}
void __sched
account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
{
unsigned long flags;
int i, q;
struct latency_record lat;
if (!latencytop_enabled)
return;
/* Long interruptible waits are generally user requested... */
if (inter && usecs > 5000)
return;
memset(&lat, 0, sizeof(lat));
lat.count = 1;
lat.time = usecs;
lat.max = usecs;
store_stacktrace(tsk, &lat);
spin_lock_irqsave(&latency_lock, flags);
account_global_scheduler_latency(tsk, &lat);
/*
* short term hack; if we're > 32 we stop; future we recycle:
*/
tsk->latency_record_count++;
if (tsk->latency_record_count >= LT_SAVECOUNT)
goto out_unlock;
for (i = 0; i < LT_SAVECOUNT ; i++) {
struct latency_record *mylat;
int same = 1;
mylat = &tsk->latency_record[i];
for (q = 0 ; q < LT_BACKTRACEDEPTH ; q++) {
if (mylat->backtrace[q] !=
lat.backtrace[q])
same = 0;
if (same && lat.backtrace[q] == 0)
break;
if (same && lat.backtrace[q] == ULONG_MAX)
break;
}
if (same) {
mylat->count++;
mylat->time += lat.time;
if (lat.time > mylat->max)
mylat->max = lat.time;
goto out_unlock;
}
}
/* Allocated a new one: */
i = tsk->latency_record_count;
memcpy(&tsk->latency_record[i], &lat, sizeof(struct latency_record));
out_unlock:
spin_unlock_irqrestore(&latency_lock, flags);
}
static int lstats_show(struct seq_file *m, void *v)
{
int i;
seq_puts(m, "Latency Top version : v0.1\n");
for (i = 0; i < MAXLR; i++) {
if (latency_record[i].backtrace[0]) {
int q;
seq_printf(m, "%i %li %li ",
latency_record[i].count,
latency_record[i].time,
latency_record[i].max);
for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
char sym[KSYM_NAME_LEN];
char *c;
if (!latency_record[i].backtrace[q])
break;
if (latency_record[i].backtrace[q] == ULONG_MAX)
break;
sprint_symbol(sym, latency_record[i].backtrace[q]);
c = strchr(sym, '+');
if (c)
*c = 0;
seq_printf(m, "%s ", sym);
}
seq_printf(m, "\n");
}
}
return 0;
}
static ssize_t
lstats_write(struct file *file, const char __user *buf, size_t count,
loff_t *offs)
{
clear_global_latency_tracing();
return count;
}
static int lstats_open(struct inode *inode, struct file *filp)
{
return single_open(filp, lstats_show, NULL);
}
static struct file_operations lstats_fops = {
.open = lstats_open,
.read = seq_read,
.write = lstats_write,
.llseek = seq_lseek,
.release = single_release,
};
static int __init init_lstats_procfs(void)
{
struct proc_dir_entry *pe;
pe = create_proc_entry("latency_stats", 0644, NULL);
if (!pe)
return -ENOMEM;
pe->proc_fops = &lstats_fops;
return 0;
}
__initcall(init_lstats_procfs);
......@@ -20,6 +20,8 @@
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
*/
#include <linux/latencytop.h>
/*
* Targeted preemption latency for CPU-bound tasks:
* (default: 20ms * (1 + ilog(ncpus)), units: nanoseconds)
......@@ -434,6 +436,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
#ifdef CONFIG_SCHEDSTATS
if (se->sleep_start) {
u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
struct task_struct *tsk = task_of(se);
if ((s64)delta < 0)
delta = 0;
......@@ -443,9 +446,12 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->sleep_start = 0;
se->sum_sleep_runtime += delta;
account_scheduler_latency(tsk, delta >> 10, 1);
}
if (se->block_start) {
u64 delta = rq_of(cfs_rq)->clock - se->block_start;
struct task_struct *tsk = task_of(se);
if ((s64)delta < 0)
delta = 0;
......@@ -462,11 +468,11 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
* time that the task spent sleeping:
*/
if (unlikely(prof_on == SLEEP_PROFILING)) {
struct task_struct *tsk = task_of(se);
profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
delta >> 20);
}
account_scheduler_latency(tsk, delta >> 10, 0);
}
#endif
}
......
......@@ -81,6 +81,7 @@ extern int compat_log;
extern int maps_protect;
extern int sysctl_stat_interval;
extern int audit_argv_kb;
extern int latencytop_enabled;
/* Constants used for minimum and maximum */
#ifdef CONFIG_DETECT_SOFTLOCKUP
......@@ -416,6 +417,15 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec_taint,
},
#endif
#ifdef CONFIG_LATENCYTOP
{
.procname = "latencytop",
.data = &latencytop_enabled,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
#endif
#ifdef CONFIG_SECURITY_CAPABILITIES
{
.procname = "cap-bound",
......
......@@ -517,4 +517,18 @@ config FAULT_INJECTION_STACKTRACE_FILTER
help
Provide stacktrace filter for fault-injection capabilities
config LATENCYTOP
bool "Latency measuring infrastructure"
select FRAME_POINTER if !MIPS
select KALLSYMS
select KALLSYMS_ALL
select STACKTRACE
select SCHEDSTATS
select SCHED_DEBUG
depends on X86 || X86_64
help
Enable this option if you want to use the LatencyTOP tool
to find out which userspace is blocking on what kernel operations.
source "samples/Kconfig"
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