/*
* Workqueue statistical tracer.
*
* Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
*
*/
#include <trace/events/workqueue.h>
#include <linux/list.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/kref.h>
#include "trace_stat.h"
#include "trace.h"
/* A cpu workqueue thread */
struct cpu_workqueue_stats {
struct list_head list;
struct kref kref;
int cpu;
pid_t pid;
/* Can be inserted from interrupt or user context, need to be atomic */
atomic_t inserted;
/*
* Don't need to be atomic, works are serialized in a single workqueue thread
* on a single CPU.
*/
unsigned int executed;
};
/* List of workqueue threads on one cpu */
struct workqueue_global_stats {
struct list_head list;
spinlock_t lock;
};
/* Don't need a global lock because allocated before the workqueues, and
* never freed.
*/
static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);
#define workqueue_cpu_stat(cpu) (&per_cpu(all_workqueue_stat, cpu))
static void cpu_workqueue_stat_free(struct kref *kref)
{
kfree(container_of(kref, struct cpu_workqueue_stats, kref));
}
/* Insertion of a work */
static void
probe_workqueue_insertion(struct task_struct *wq_thread,
struct work_struct *work)
{
int cpu = cpumask_first(&wq_thread->cpus_allowed);
struct cpu_workqueue_stats *node;
unsigned long flags;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
if (node->pid == wq_thread->pid) {
atomic_inc(&node->inserted);
goto found;
}
}
pr_debug("trace_workqueue: entry not found\n");
found:
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}
/* Execution of a work */
static void
probe_workqueue_execution(struct task_struct *wq_thread,
struct work_struct *work)
{
int cpu = cpumask_first(&wq_thread->cpus_allowed);
struct cpu_workqueue_stats *node;
unsigned long flags;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
if (node->pid == wq_thread->pid) {
node->executed++;
goto found;
}
}
pr_debug("trace_workqueue: entry not found\n");
found:
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}
/* Creation of a cpu workqueue thread */
static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)
{
struct cpu_workqueue_stats *cws;
unsigned long flags;
WARN_ON(cpu < 0);
/* Workqueues are sometimes created in atomic context */
cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);
if (!cws) {
pr_warning("trace_workqueue: not enough memory\n");
return;
}
INIT_LIST_HEAD(&cws->list);
kref_init(&cws->kref);
cws->cpu = cpu;
cws->pid = wq_thread->pid;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
list_add_tail(&cws->list, &workqueue_cpu_stat(cpu)->list);
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}
/* Destruction of a cpu workqueue thread */
static void probe_workqueue_destruction(struct task_struct *wq_thread)
{
/* Workqueue only execute on one cpu */
int cpu = cpumask_first(&wq_thread->cpus_allowed);
struct cpu_workqueue_stats *node, *next;
unsigned long flags;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
list) {
if (node->pid == wq_thread->pid) {
list_del(&node->list);
kref_put(&node->kref, cpu_workqueue_stat_free);
goto found;
}
}
pr_debug("trace_workqueue: don't find workqueue to destroy\n");
found:
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}
static struct cpu_workqueue_stats *workqueue_stat_start_cpu(int cpu)
{
unsigned long flags;
struct cpu_workqueue_stats *ret = NULL;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
if (!list_empty(&workqueue_cpu_stat(cpu)->list)) {
ret = list_entry(workqueue_cpu_stat(cpu)->list.next,
struct cpu_workqueue_stats, list);
kref_get(&ret->kref);
}
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
return ret;
}
static void *workqueue_stat_start(struct tracer_stat *trace)
{
int cpu;
void *ret = NULL;
for_each_possible_cpu(cpu) {
ret = workqueue_stat_start_cpu(cpu);
if (ret)
return ret;
}
return NULL;
}
static void *workqueue_stat_next(void *prev, int idx)
{
struct cpu_workqueue_stats *prev_cws = prev;
struct cpu_workqueue_stats *ret;
int cpu = prev_cws->cpu;
unsigned long flags;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
do {
cpu = cpumask_next(cpu, cpu_possible_mask);
if (cpu >= nr_cpu_ids)
return NULL;
} while (!(ret = workqueue_stat_start_cpu(cpu)));
return ret;
} else {
ret = list_entry(prev_cws->list.next,
struct cpu_workqueue_stats, list);
kref_get(&ret->kref);
}
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
return ret;
}
static int workqueue_stat_show(struct seq_file *s, void *p)
{
struct cpu_workqueue_stats *cws = p;
struct pid *pid;
struct task_struct *tsk;
pid = find_get_pid(cws->pid);
if (pid) {
tsk = get_pid_task(pid, PIDTYPE_PID);
if (tsk) {
seq_printf(s, "%3d %6d %6u %s\n", cws->cpu,
atomic_read(&cws->inserted), cws->executed,
tsk->comm);
put_task_struct(tsk);
}
put_pid(pid);
}
return 0;
}
static void workqueue_stat_release(void *stat)
{
struct cpu_workqueue_stats *node = stat;
kref_put(&node->kref, cpu_workqueue_stat_free);
}
static int workqueue_stat_headers(struct seq_file *s)
{
seq_printf(s, "# CPU INSERTED EXECUTED NAME\n");
seq_printf(s, "# | | | |\n");
return 0;
}
struct tracer_stat workqueue_stats __read_mostly = {
.name = "workqueues",
.stat_start = workqueue_stat_start,
.stat_next = workqueue_stat_next,
.stat_show = workqueue_stat_show,
.stat_release = workqueue_stat_release,
.stat_headers = workqueue_stat_headers
};
int __init stat_workqueue_init(void)
{
if (register_stat_tracer(&workqueue_stats)) {
pr_warning("Unable to register workqueue stat tracer\n");
return 1;
}
return 0;
}
fs_initcall(stat_workqueue_init);
/*
* Workqueues are created very early, just after pre-smp initcalls.
* So we must register our tracepoints at this stage.
*/
int __init trace_workqueue_early_init(void)
{
int ret, cpu;
ret = register_trace_workqueue_insertion(probe_workqueue_insertion);
if (ret)
goto out;
ret = register_trace_workqueue_execution(probe_workqueue_execution);
if (ret)
goto no_insertion;
ret = register_trace_workqueue_creation(probe_workqueue_creation);
if (ret)
goto no_execution;
ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
if (ret)
goto no_creation;
for_each_possible_cpu(cpu) {
spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
}
return 0;
no_creation:
unregister_trace_workqueue_creation(probe_workqueue_creation);
no_execution:
unregister_trace_workqueue_execution(probe_workqueue_execution);
no_insertion:
unregister_trace_workqueue_insertion(probe_workqueue_insertion);
out:
pr_warning("trace_workqueue: unable to trace workqueues\n");
return 1;
}
early_initcall(trace_workqueue_early_init);
