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
cpu_workqueue_stat_free(struct kref * kref)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
probe_workqueue_insertion(void * ignore,struct task_struct * wq_thread,struct work_struct * work)52 probe_workqueue_insertion(void *ignore,
53 struct task_struct *wq_thread,
54 struct work_struct *work)
55 {
56 int cpu = cpumask_first(&wq_thread->cpus_allowed);
57 struct cpu_workqueue_stats *node;
58 unsigned long flags;
59
60 spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
61 list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
62 if (node->pid == wq_thread->pid) {
63 atomic_inc(&node->inserted);
64 goto found;
65 }
66 }
67 pr_debug("trace_workqueue: entry not found\n");
68 found:
69 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
70 }
71
72 /* Execution of a work */
73 static void
probe_workqueue_execution(void * ignore,struct task_struct * wq_thread,struct work_struct * work)74 probe_workqueue_execution(void *ignore,
75 struct task_struct *wq_thread,
76 struct work_struct *work)
77 {
78 int cpu = cpumask_first(&wq_thread->cpus_allowed);
79 struct cpu_workqueue_stats *node;
80 unsigned long flags;
81
82 spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
83 list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list) {
84 if (node->pid == wq_thread->pid) {
85 node->executed++;
86 goto found;
87 }
88 }
89 pr_debug("trace_workqueue: entry not found\n");
90 found:
91 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
92 }
93
94 /* Creation of a cpu workqueue thread */
probe_workqueue_creation(void * ignore,struct task_struct * wq_thread,int cpu)95 static void probe_workqueue_creation(void *ignore,
96 struct task_struct *wq_thread, int cpu)
97 {
98 struct cpu_workqueue_stats *cws;
99 unsigned long flags;
100
101 WARN_ON(cpu < 0);
102
103 /* Workqueues are sometimes created in atomic context */
104 cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);
105 if (!cws) {
106 pr_warning("trace_workqueue: not enough memory\n");
107 return;
108 }
109 INIT_LIST_HEAD(&cws->list);
110 kref_init(&cws->kref);
111 cws->cpu = cpu;
112 cws->pid = wq_thread->pid;
113
114 spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
115 list_add_tail(&cws->list, &workqueue_cpu_stat(cpu)->list);
116 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
117 }
118
119 /* Destruction of a cpu workqueue thread */
120 static void
probe_workqueue_destruction(void * ignore,struct task_struct * wq_thread)121 probe_workqueue_destruction(void *ignore, struct task_struct *wq_thread)
122 {
123 /* Workqueue only execute on one cpu */
124 int cpu = cpumask_first(&wq_thread->cpus_allowed);
125 struct cpu_workqueue_stats *node, *next;
126 unsigned long flags;
127
128 spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
129 list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
130 list) {
131 if (node->pid == wq_thread->pid) {
132 list_del(&node->list);
133 kref_put(&node->kref, cpu_workqueue_stat_free);
134 goto found;
135 }
136 }
137
138 pr_debug("trace_workqueue: don't find workqueue to destroy\n");
139 found:
140 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
141
142 }
143
workqueue_stat_start_cpu(int cpu)144 static struct cpu_workqueue_stats *workqueue_stat_start_cpu(int cpu)
145 {
146 unsigned long flags;
147 struct cpu_workqueue_stats *ret = NULL;
148
149
150 spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
151
152 if (!list_empty(&workqueue_cpu_stat(cpu)->list)) {
153 ret = list_entry(workqueue_cpu_stat(cpu)->list.next,
154 struct cpu_workqueue_stats, list);
155 kref_get(&ret->kref);
156 }
157
158 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
159
160 return ret;
161 }
162
workqueue_stat_start(struct tracer_stat * trace)163 static void *workqueue_stat_start(struct tracer_stat *trace)
164 {
165 int cpu;
166 void *ret = NULL;
167
168 for_each_possible_cpu(cpu) {
169 ret = workqueue_stat_start_cpu(cpu);
170 if (ret)
171 return ret;
172 }
173 return NULL;
174 }
175
workqueue_stat_next(void * prev,int idx)176 static void *workqueue_stat_next(void *prev, int idx)
177 {
178 struct cpu_workqueue_stats *prev_cws = prev;
179 struct cpu_workqueue_stats *ret;
180 int cpu = prev_cws->cpu;
181 unsigned long flags;
182
183 spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
184 if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
185 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
186 do {
187 cpu = cpumask_next(cpu, cpu_possible_mask);
188 if (cpu >= nr_cpu_ids)
189 return NULL;
190 } while (!(ret = workqueue_stat_start_cpu(cpu)));
191 return ret;
192 } else {
193 ret = list_entry(prev_cws->list.next,
194 struct cpu_workqueue_stats, list);
195 kref_get(&ret->kref);
196 }
197 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
198
199 return ret;
200 }
201
workqueue_stat_show(struct seq_file * s,void * p)202 static int workqueue_stat_show(struct seq_file *s, void *p)
203 {
204 struct cpu_workqueue_stats *cws = p;
205 struct pid *pid;
206 struct task_struct *tsk;
207
208 pid = find_get_pid(cws->pid);
209 if (pid) {
210 tsk = get_pid_task(pid, PIDTYPE_PID);
211 if (tsk) {
212 seq_printf(s, "%3d %6d %6u %s\n", cws->cpu,
213 atomic_read(&cws->inserted), cws->executed,
214 tsk->comm);
215 put_task_struct(tsk);
216 }
217 put_pid(pid);
218 }
219
220 return 0;
221 }
222
workqueue_stat_release(void * stat)223 static void workqueue_stat_release(void *stat)
224 {
225 struct cpu_workqueue_stats *node = stat;
226
227 kref_put(&node->kref, cpu_workqueue_stat_free);
228 }
229
workqueue_stat_headers(struct seq_file * s)230 static int workqueue_stat_headers(struct seq_file *s)
231 {
232 seq_printf(s, "# CPU INSERTED EXECUTED NAME\n");
233 seq_printf(s, "# | | | |\n");
234 return 0;
235 }
236
237 struct tracer_stat workqueue_stats __read_mostly = {
238 .name = "workqueues",
239 .stat_start = workqueue_stat_start,
240 .stat_next = workqueue_stat_next,
241 .stat_show = workqueue_stat_show,
242 .stat_release = workqueue_stat_release,
243 .stat_headers = workqueue_stat_headers
244 };
245
246
stat_workqueue_init(void)247 int __init stat_workqueue_init(void)
248 {
249 if (register_stat_tracer(&workqueue_stats)) {
250 pr_warning("Unable to register workqueue stat tracer\n");
251 return 1;
252 }
253
254 return 0;
255 }
256 fs_initcall(stat_workqueue_init);
257
258 /*
259 * Workqueues are created very early, just after pre-smp initcalls.
260 * So we must register our tracepoints at this stage.
261 */
trace_workqueue_early_init(void)262 int __init trace_workqueue_early_init(void)
263 {
264 int ret, cpu;
265
266 for_each_possible_cpu(cpu) {
267 spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
268 INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
269 }
270
271 ret = register_trace_workqueue_insertion(probe_workqueue_insertion, NULL);
272 if (ret)
273 goto out;
274
275 ret = register_trace_workqueue_execution(probe_workqueue_execution, NULL);
276 if (ret)
277 goto no_insertion;
278
279 ret = register_trace_workqueue_creation(probe_workqueue_creation, NULL);
280 if (ret)
281 goto no_execution;
282
283 ret = register_trace_workqueue_destruction(probe_workqueue_destruction, NULL);
284 if (ret)
285 goto no_creation;
286
287 return 0;
288
289 no_creation:
290 unregister_trace_workqueue_creation(probe_workqueue_creation, NULL);
291 no_execution:
292 unregister_trace_workqueue_execution(probe_workqueue_execution, NULL);
293 no_insertion:
294 unregister_trace_workqueue_insertion(probe_workqueue_insertion, NULL);
295 out:
296 pr_warning("trace_workqueue: unable to trace workqueues\n");
297
298 return 1;
299 }
300 early_initcall(trace_workqueue_early_init);
301