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);