linux/kernel/trace/trace_workqueue.c
Lai Jiangshan 3690b5e6fd trace_workqueue: use percpu data for workqueue stat
Impact: use percpu data instead of a global structure

Use:

   static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);

instead of allocating a global structure.

percpu data also works well on NUMA.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-20 13:06:59 +01:00

281 lines
7 KiB
C

/*
* Workqueue statistical tracer.
*
* Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
*
*/
#include <trace/workqueue.h>
#include <linux/list.h>
#include <linux/percpu.h>
#include "trace_stat.h"
#include "trace.h"
/* A cpu workqueue thread */
struct cpu_workqueue_stats {
struct list_head list;
/* Useful to know if we print the cpu headers */
bool first_entry;
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))
/* 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, *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) {
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, *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) {
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 || cpu >= num_possible_cpus());
/* 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;
}
tracing_record_cmdline(wq_thread);
INIT_LIST_HEAD(&cws->list);
cws->cpu = cpu;
cws->pid = wq_thread->pid;
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
if (list_empty(&workqueue_cpu_stat(cpu)->list))
cws->first_entry = true;
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);
kfree(node);
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);
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
return ret;
}
static void *workqueue_stat_start(void)
{
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;
int cpu = prev_cws->cpu;
unsigned long flags;
void *ret = NULL;
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);
for (++cpu ; cpu < num_possible_cpus(); cpu++) {
ret = workqueue_stat_start_cpu(cpu);
if (ret)
return ret;
}
return NULL;
}
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
return list_entry(prev_cws->list.next, struct cpu_workqueue_stats,
list);
}
static int workqueue_stat_show(struct seq_file *s, void *p)
{
struct cpu_workqueue_stats *cws = p;
unsigned long flags;
int cpu = cws->cpu;
seq_printf(s, "%3d %6d %6u %s\n", cws->cpu,
atomic_read(&cws->inserted),
cws->executed,
trace_find_cmdline(cws->pid));
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
if (&cws->list == workqueue_cpu_stat(cpu)->list.next)
seq_printf(s, "\n");
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
return 0;
}
static int workqueue_stat_headers(struct seq_file *s)
{
seq_printf(s, "# CPU INSERTED EXECUTED NAME\n");
seq_printf(s, "# | | | |\n\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_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);