cc2d2faa7d9e037734f1e4c11e87418c4a3a5400
[linux-2.6.git] / 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 <linux/slab.h>
13 #include <linux/kref.h>
14 #include "trace_stat.h"
15 #include "trace.h"
16
17
18 /* A cpu workqueue thread */
19 struct cpu_workqueue_stats {
20         struct list_head            list;
21         struct kref                 kref;
22         int                         cpu;
23         pid_t                       pid;
24 /* Can be inserted from interrupt or user context, need to be atomic */
25         atomic_t                    inserted;
26 /*
27  *  Don't need to be atomic, works are serialized in a single workqueue thread
28  *  on a single CPU.
29  */
30         unsigned int                executed;
31 };
32
33 /* List of workqueue threads on one cpu */
34 struct workqueue_global_stats {
35         struct list_head        list;
36         spinlock_t              lock;
37 };
38
39 /* Don't need a global lock because allocated before the workqueues, and
40  * never freed.
41  */
42 static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);
43 #define workqueue_cpu_stat(cpu) (&per_cpu(all_workqueue_stat, cpu))
44
45 static void cpu_workqueue_stat_free(struct kref *kref)
46 {
47         kfree(container_of(kref, struct cpu_workqueue_stats, kref));
48 }
49
50 /* Insertion of a work */
51 static void
52 probe_workqueue_insertion(struct task_struct *wq_thread,
53                           struct work_struct *work)
54 {
55         int cpu = cpumask_first(&wq_thread->cpus_allowed);
56         struct cpu_workqueue_stats *node;
57         unsigned long flags;
58
59         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
60         list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
61                 if (node->pid == wq_thread->pid) {
62                         atomic_inc(&node->inserted);
63                         goto found;
64                 }
65         }
66         pr_debug("trace_workqueue: entry not found\n");
67 found:
68         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
69 }
70
71 /* Execution of a work */
72 static void
73 probe_workqueue_execution(struct task_struct *wq_thread,
74                           struct work_struct *work)
75 {
76         int cpu = cpumask_first(&wq_thread->cpus_allowed);
77         struct cpu_workqueue_stats *node;
78         unsigned long flags;
79
80         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
81         list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
82                 if (node->pid == wq_thread->pid) {
83                         node->executed++;
84                         goto found;
85                 }
86         }
87         pr_debug("trace_workqueue: entry not found\n");
88 found:
89         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
90 }
91
92 /* Creation of a cpu workqueue thread */
93 static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)
94 {
95         struct cpu_workqueue_stats *cws;
96         unsigned long flags;
97
98         WARN_ON(cpu < 0);
99
100         /* Workqueues are sometimes created in atomic context */
101         cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);
102         if (!cws) {
103                 pr_warning("trace_workqueue: not enough memory\n");
104                 return;
105         }
106         INIT_LIST_HEAD(&cws->list);
107         kref_init(&cws->kref);
108         cws->cpu = cpu;
109         cws->pid = wq_thread->pid;
110
111         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
112         list_add_tail(&cws->list, &workqueue_cpu_stat(cpu)->list);
113         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
114 }
115
116 /* Destruction of a cpu workqueue thread */
117 static void probe_workqueue_destruction(struct task_struct *wq_thread)
118 {
119         /* Workqueue only execute on one cpu */
120         int cpu = cpumask_first(&wq_thread->cpus_allowed);
121         struct cpu_workqueue_stats *node, *next;
122         unsigned long flags;
123
124         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
125         list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
126                                                         list) {
127                 if (node->pid == wq_thread->pid) {
128                         list_del(&node->list);
129                         kref_put(&node->kref, cpu_workqueue_stat_free);
130                         goto found;
131                 }
132         }
133
134         pr_debug("trace_workqueue: don't find workqueue to destroy\n");
135 found:
136         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
137
138 }
139
140 static struct cpu_workqueue_stats *workqueue_stat_start_cpu(int cpu)
141 {
142         unsigned long flags;
143         struct cpu_workqueue_stats *ret = NULL;
144
145
146         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
147
148         if (!list_empty(&workqueue_cpu_stat(cpu)->list)) {
149                 ret = list_entry(workqueue_cpu_stat(cpu)->list.next,
150                                  struct cpu_workqueue_stats, list);
151                 kref_get(&ret->kref);
152         }
153
154         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
155
156         return ret;
157 }
158
159 static void *workqueue_stat_start(struct tracer_stat *trace)
160 {
161         int cpu;
162         void *ret = NULL;
163
164         for_each_possible_cpu(cpu) {
165                 ret = workqueue_stat_start_cpu(cpu);
166                 if (ret)
167                         return ret;
168         }
169         return NULL;
170 }
171
172 static void *workqueue_stat_next(void *prev, int idx)
173 {
174         struct cpu_workqueue_stats *prev_cws = prev;
175         struct cpu_workqueue_stats *ret;
176         int cpu = prev_cws->cpu;
177         unsigned long flags;
178
179         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
180         if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
181                 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
182                 do {
183                         cpu = cpumask_next(cpu, cpu_possible_mask);
184                         if (cpu >= nr_cpu_ids)
185                                 return NULL;
186                 } while (!(ret = workqueue_stat_start_cpu(cpu)));
187                 return ret;
188         } else {
189                 ret = list_entry(prev_cws->list.next,
190                                  struct cpu_workqueue_stats, list);
191                 kref_get(&ret->kref);
192         }
193         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
194
195         return ret;
196 }
197
198 static int workqueue_stat_show(struct seq_file *s, void *p)
199 {
200         struct cpu_workqueue_stats *cws = p;
201         struct pid *pid;
202         struct task_struct *tsk;
203
204         pid = find_get_pid(cws->pid);
205         if (pid) {
206                 tsk = get_pid_task(pid, PIDTYPE_PID);
207                 if (tsk) {
208                         seq_printf(s, "%3d %6d     %6u       %s\n", cws->cpu,
209                                    atomic_read(&cws->inserted), cws->executed,
210                                    tsk->comm);
211                         put_task_struct(tsk);
212                 }
213                 put_pid(pid);
214         }
215
216         return 0;
217 }
218
219 static void workqueue_stat_release(void *stat)
220 {
221         struct cpu_workqueue_stats *node = stat;
222
223         kref_put(&node->kref, cpu_workqueue_stat_free);
224 }
225
226 static int workqueue_stat_headers(struct seq_file *s)
227 {
228         seq_printf(s, "# CPU  INSERTED  EXECUTED   NAME\n");
229         seq_printf(s, "# |      |         |          |\n");
230         return 0;
231 }
232
233 struct tracer_stat workqueue_stats __read_mostly = {
234         .name = "workqueues",
235         .stat_start = workqueue_stat_start,
236         .stat_next = workqueue_stat_next,
237         .stat_show = workqueue_stat_show,
238         .stat_release = workqueue_stat_release,
239         .stat_headers = workqueue_stat_headers
240 };
241
242
243 int __init stat_workqueue_init(void)
244 {
245         if (register_stat_tracer(&workqueue_stats)) {
246                 pr_warning("Unable to register workqueue stat tracer\n");
247                 return 1;
248         }
249
250         return 0;
251 }
252 fs_initcall(stat_workqueue_init);
253
254 /*
255  * Workqueues are created very early, just after pre-smp initcalls.
256  * So we must register our tracepoints at this stage.
257  */
258 int __init trace_workqueue_early_init(void)
259 {
260         int ret, cpu;
261
262         ret = register_trace_workqueue_insertion(probe_workqueue_insertion);
263         if (ret)
264                 goto out;
265
266         ret = register_trace_workqueue_execution(probe_workqueue_execution);
267         if (ret)
268                 goto no_insertion;
269
270         ret = register_trace_workqueue_creation(probe_workqueue_creation);
271         if (ret)
272                 goto no_execution;
273
274         ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
275         if (ret)
276                 goto no_creation;
277
278         for_each_possible_cpu(cpu) {
279                 spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
280                 INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
281         }
282
283         return 0;
284
285 no_creation:
286         unregister_trace_workqueue_creation(probe_workqueue_creation);
287 no_execution:
288         unregister_trace_workqueue_execution(probe_workqueue_execution);
289 no_insertion:
290         unregister_trace_workqueue_insertion(probe_workqueue_insertion);
291 out:
292         pr_warning("trace_workqueue: unable to trace workqueues\n");
293
294         return 1;
295 }
296 early_initcall(trace_workqueue_early_init);