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         unsigned long flags;
 189         int cpu = cws->cpu;
 190         struct pid *pid;
 191         struct task_struct *tsk;
 192
 193         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
 194         if (&cws->list == workqueue_cpu_stat(cpu)->list.next)
 195                 seq_printf(s, "\n");
 196         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
 197
 198         pid = find_get_pid(cws->pid);
 199         if (pid) {
 200                 tsk = get_pid_task(pid, PIDTYPE_PID);
 201                 if (tsk) {
 202                         seq_printf(s, "%3d %6d     %6u       %s\n", cws->cpu,
 203                                    atomic_read(&cws->inserted), cws->executed,
 204                                    tsk->comm);
 205                         put_task_struct(tsk);
 206                 }
 207                 put_pid(pid);
 208         }
 209
 210         return 0;
 211 }
 212
 213 static int workqueue_stat_headers(struct seq_file *s)
 214 {
 215         seq_printf(s, "# CPU  INSERTED  EXECUTED   NAME\n");
 216         seq_printf(s, "# |      |         |          |\n");
 217         return 0;
 218 }
 219
 220 struct tracer_stat workqueue_stats __read_mostly = {
 221         .name = "workqueues",
 222         .stat_start = workqueue_stat_start,
 223         .stat_next = workqueue_stat_next,
 224         .stat_show = workqueue_stat_show,
 225         .stat_headers = workqueue_stat_headers
 226 };
 227
 228
 229 int __init stat_workqueue_init(void)
 230 {
 231         if (register_stat_tracer(&workqueue_stats)) {
 232                 pr_warning("Unable to register workqueue stat tracer\n");
 233                 return 1;
 234         }
 235
 236         return 0;
 237 }
 238 fs_initcall(stat_workqueue_init);
 239
 240 /*
 241  * Workqueues are created very early, just after pre-smp initcalls.
 242  * So we must register our tracepoints at this stage.
 243  */
 244 int __init trace_workqueue_early_init(void)
 245 {
 246         int ret, cpu;
 247
 248         ret = register_trace_workqueue_insertion(probe_workqueue_insertion);
 249         if (ret)
 250                 goto out;
 251
 252         ret = register_trace_workqueue_execution(probe_workqueue_execution);
 253         if (ret)
 254                 goto no_insertion;
 255
 256         ret = register_trace_workqueue_creation(probe_workqueue_creation);
 257         if (ret)
 258                 goto no_execution;
 259
 260         ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
 261         if (ret)
 262                 goto no_creation;
 263
 264         for_each_possible_cpu(cpu) {
 265                 spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
 266                 INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
 267         }
 268
 269         return 0;
 270
 271 no_creation:
 272         unregister_trace_workqueue_creation(probe_workqueue_creation);
 273 no_execution:
 274         unregister_trace_workqueue_execution(probe_workqueue_execution);
 275 no_insertion:
 276         unregister_trace_workqueue_insertion(probe_workqueue_insertion);
 277 out:
 278         pr_warning("trace_workqueue: unable to trace workqueues\n");
 279
 280         return 1;
 281 }
 282 early_initcall(trace_workqueue_early_init);