Merge branch 'tracing/ftrace' into tracing/core
[linux-2.6] / kernel / trace / trace_workqueue.c
1 /*
2  * Workqueue statistical tracer.
3  *
4  * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
5  *
6  */
7
8
9 #include <trace/events/workqueue.h>
10 #include <linux/list.h>
11 #include <linux/percpu.h>
12 #include "trace_stat.h"
13 #include "trace.h"
14
15
16 /* A cpu workqueue thread */
17 struct cpu_workqueue_stats {
18         struct list_head            list;
19         int                         cpu;
20         pid_t                       pid;
21 /* Can be inserted from interrupt or user context, need to be atomic */
22         atomic_t                    inserted;
23 /*
24  *  Don't need to be atomic, works are serialized in a single workqueue thread
25  *  on a single CPU.
26  */
27         unsigned int                executed;
28 };
29
30 /* List of workqueue threads on one cpu */
31 struct workqueue_global_stats {
32         struct list_head        list;
33         spinlock_t              lock;
34 };
35
36 /* Don't need a global lock because allocated before the workqueues, and
37  * never freed.
38  */
39 static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);
40 #define workqueue_cpu_stat(cpu) (&per_cpu(all_workqueue_stat, cpu))
41
42 /* Insertion of a work */
43 static void
44 probe_workqueue_insertion(struct task_struct *wq_thread,
45                           struct work_struct *work)
46 {
47         int cpu = cpumask_first(&wq_thread->cpus_allowed);
48         struct cpu_workqueue_stats *node;
49         unsigned long flags;
50
51         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
52         list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
53                 if (node->pid == wq_thread->pid) {
54                         atomic_inc(&node->inserted);
55                         goto found;
56                 }
57         }
58         pr_debug("trace_workqueue: entry not found\n");
59 found:
60         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
61 }
62
63 /* Execution of a work */
64 static void
65 probe_workqueue_execution(struct task_struct *wq_thread,
66                           struct work_struct *work)
67 {
68         int cpu = cpumask_first(&wq_thread->cpus_allowed);
69         struct cpu_workqueue_stats *node;
70         unsigned long flags;
71
72         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
73         list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
74                 if (node->pid == wq_thread->pid) {
75                         node->executed++;
76                         goto found;
77                 }
78         }
79         pr_debug("trace_workqueue: entry not found\n");
80 found:
81         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
82 }
83
84 /* Creation of a cpu workqueue thread */
85 static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)
86 {
87         struct cpu_workqueue_stats *cws;
88         unsigned long flags;
89
90         WARN_ON(cpu < 0);
91
92         /* Workqueues are sometimes created in atomic context */
93         cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);
94         if (!cws) {
95                 pr_warning("trace_workqueue: not enough memory\n");
96                 return;
97         }
98         INIT_LIST_HEAD(&cws->list);
99         cws->cpu = cpu;
100
101         cws->pid = wq_thread->pid;
102
103         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
104         list_add_tail(&cws->list, &workqueue_cpu_stat(cpu)->list);
105         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
106 }
107
108 /* Destruction of a cpu workqueue thread */
109 static void probe_workqueue_destruction(struct task_struct *wq_thread)
110 {
111         /* Workqueue only execute on one cpu */
112         int cpu = cpumask_first(&wq_thread->cpus_allowed);
113         struct cpu_workqueue_stats *node, *next;
114         unsigned long flags;
115
116         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
117         list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
118                                                         list) {
119                 if (node->pid == wq_thread->pid) {
120                         list_del(&node->list);
121                         kfree(node);
122                         goto found;
123                 }
124         }
125
126         pr_debug("trace_workqueue: don't find workqueue to destroy\n");
127 found:
128         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
129
130 }
131
132 static struct cpu_workqueue_stats *workqueue_stat_start_cpu(int cpu)
133 {
134         unsigned long flags;
135         struct cpu_workqueue_stats *ret = NULL;
136
137
138         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
139
140         if (!list_empty(&workqueue_cpu_stat(cpu)->list))
141                 ret = list_entry(workqueue_cpu_stat(cpu)->list.next,
142                                  struct cpu_workqueue_stats, list);
143
144         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
145
146         return ret;
147 }
148
149 static void *workqueue_stat_start(struct tracer_stat *trace)
150 {
151         int cpu;
152         void *ret = NULL;
153
154         for_each_possible_cpu(cpu) {
155                 ret = workqueue_stat_start_cpu(cpu);
156                 if (ret)
157                         return ret;
158         }
159         return NULL;
160 }
161
162 static void *workqueue_stat_next(void *prev, int idx)
163 {
164         struct cpu_workqueue_stats *prev_cws = prev;
165         int cpu = prev_cws->cpu;
166         unsigned long flags;
167         void *ret = NULL;
168
169         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
170         if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
171                 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
172                 do {
173                         cpu = cpumask_next(cpu, cpu_possible_mask);
174                         if (cpu >= nr_cpu_ids)
175                                 return NULL;
176                 } while (!(ret = workqueue_stat_start_cpu(cpu)));
177                 return ret;
178         }
179         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
180
181         return list_entry(prev_cws->list.next, struct cpu_workqueue_stats,
182                           list);
183 }
184
185 static int workqueue_stat_show(struct seq_file *s, void *p)
186 {
187         struct cpu_workqueue_stats *cws = p;
188         struct pid *pid;
189         struct task_struct *tsk;
190
191         pid = find_get_pid(cws->pid);
192         if (pid) {
193                 tsk = get_pid_task(pid, PIDTYPE_PID);
194                 if (tsk) {
195                         seq_printf(s, "%3d %6d     %6u       %s\n", cws->cpu,
196                                    atomic_read(&cws->inserted), cws->executed,
197                                    tsk->comm);
198                         put_task_struct(tsk);
199                 }
200                 put_pid(pid);
201         }
202
203         return 0;
204 }
205
206 static int workqueue_stat_headers(struct seq_file *s)
207 {
208         seq_printf(s, "# CPU  INSERTED  EXECUTED   NAME\n");
209         seq_printf(s, "# |      |         |          |\n");
210         return 0;
211 }
212
213 struct tracer_stat workqueue_stats __read_mostly = {
214         .name = "workqueues",
215         .stat_start = workqueue_stat_start,
216         .stat_next = workqueue_stat_next,
217         .stat_show = workqueue_stat_show,
218         .stat_headers = workqueue_stat_headers
219 };
220
221
222 int __init stat_workqueue_init(void)
223 {
224         if (register_stat_tracer(&workqueue_stats)) {
225                 pr_warning("Unable to register workqueue stat tracer\n");
226                 return 1;
227         }
228
229         return 0;
230 }
231 fs_initcall(stat_workqueue_init);
232
233 /*
234  * Workqueues are created very early, just after pre-smp initcalls.
235  * So we must register our tracepoints at this stage.
236  */
237 int __init trace_workqueue_early_init(void)
238 {
239         int ret, cpu;
240
241         ret = register_trace_workqueue_insertion(probe_workqueue_insertion);
242         if (ret)
243                 goto out;
244
245         ret = register_trace_workqueue_execution(probe_workqueue_execution);
246         if (ret)
247                 goto no_insertion;
248
249         ret = register_trace_workqueue_creation(probe_workqueue_creation);
250         if (ret)
251                 goto no_execution;
252
253         ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
254         if (ret)
255                 goto no_creation;
256
257         for_each_possible_cpu(cpu) {
258                 spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
259                 INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
260         }
261
262         return 0;
263
264 no_creation:
265         unregister_trace_workqueue_creation(probe_workqueue_creation);
266 no_execution:
267         unregister_trace_workqueue_execution(probe_workqueue_execution);
268 no_insertion:
269         unregister_trace_workqueue_insertion(probe_workqueue_insertion);
270 out:
271         pr_warning("trace_workqueue: unable to trace workqueues\n");
272
273         return 1;
274 }
275 early_initcall(trace_workqueue_early_init);