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/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 /* Useful to know if we print the cpu headers */
  20         bool                        first_entry;
  21         int                         cpu;
  22         pid_t                       pid;
  23 /* Can be inserted from interrupt or user context, need to be atomic */
  24         atomic_t                    inserted;
  25 /*
  26  *  Don't need to be atomic, works are serialized in a single workqueue thread
  27  *  on a single CPU.
  28  */
  29         unsigned int                executed;
  30 };
  31
  32 /* List of workqueue threads on one cpu */
  33 struct workqueue_global_stats {
  34         struct list_head        list;
  35         spinlock_t              lock;
  36 };
  37
  38 /* Don't need a global lock because allocated before the workqueues, and
  39  * never freed.
  40  */
  41 static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);
  42 #define workqueue_cpu_stat(cpu) (&per_cpu(all_workqueue_stat, cpu))
  43
  44 /* Insertion of a work */
  45 static void
  46 probe_workqueue_insertion(struct task_struct *wq_thread,
  47                           struct work_struct *work)
  48 {
  49         int cpu = cpumask_first(&wq_thread->cpus_allowed);
  50         struct cpu_workqueue_stats *node, *next;
  51         unsigned long flags;
  52
  53         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
  54         list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
  55                                                         list) {
  56                 if (node->pid == wq_thread->pid) {
  57                         atomic_inc(&node->inserted);
  58                         goto found;
  59                 }
  60         }
  61         pr_debug("trace_workqueue: entry not found\n");
  62 found:
  63         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
  64 }
  65
  66 /* Execution of a work */
  67 static void
  68 probe_workqueue_execution(struct task_struct *wq_thread,
  69                           struct work_struct *work)
  70 {
  71         int cpu = cpumask_first(&wq_thread->cpus_allowed);
  72         struct cpu_workqueue_stats *node, *next;
  73         unsigned long flags;
  74
  75         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
  76         list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
  77                                                         list) {
  78                 if (node->pid == wq_thread->pid) {
  79                         node->executed++;
  80                         goto found;
  81                 }
  82         }
  83         pr_debug("trace_workqueue: entry not found\n");
  84 found:
  85         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
  86 }
  87
  88 /* Creation of a cpu workqueue thread */
  89 static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)
  90 {
  91         struct cpu_workqueue_stats *cws;
  92         unsigned long flags;
  93
  94         WARN_ON(cpu < 0 || cpu >= num_possible_cpus());
  95
  96         /* Workqueues are sometimes created in atomic context */
  97         cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);
  98         if (!cws) {
  99                 pr_warning("trace_workqueue: not enough memory\n");
 100                 return;
 101         }
 102         tracing_record_cmdline(wq_thread);
 103
 104         INIT_LIST_HEAD(&cws->list);
 105         cws->cpu = cpu;
 106
 107         cws->pid = wq_thread->pid;
 108
 109         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
 110         if (list_empty(&workqueue_cpu_stat(cpu)->list))
 111                 cws->first_entry = true;
 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                         kfree(node);
 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
 152         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
 153
 154         return ret;
 155 }
 156
 157 static void *workqueue_stat_start(void)
 158 {
 159         int cpu;
 160         void *ret = NULL;
 161
 162         for_each_possible_cpu(cpu) {
 163                 ret = workqueue_stat_start_cpu(cpu);
 164                 if (ret)
 165                         return ret;
 166         }
 167         return NULL;
 168 }
 169
 170 static void *workqueue_stat_next(void *prev, int idx)
 171 {
 172         struct cpu_workqueue_stats *prev_cws = prev;
 173         int cpu = prev_cws->cpu;
 174         unsigned long flags;
 175         void *ret = NULL;
 176
 177         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
 178         if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
 179                 spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
 180                 for (++cpu ; cpu < num_possible_cpus(); cpu++) {
 181                         ret = workqueue_stat_start_cpu(cpu);
 182                         if (ret)
 183                                 return ret;
 184                 }
 185                 return NULL;
 186         }
 187         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
 188
 189         return list_entry(prev_cws->list.next, struct cpu_workqueue_stats,
 190                           list);
 191 }
 192
 193 static int workqueue_stat_show(struct seq_file *s, void *p)
 194 {
 195         struct cpu_workqueue_stats *cws = p;
 196         unsigned long flags;
 197         int cpu = cws->cpu;
 198
 199         seq_printf(s, "%3d %6d     %6u       %s\n", cws->cpu,
 200                    atomic_read(&cws->inserted),
 201                    cws->executed,
 202                    trace_find_cmdline(cws->pid));
 203
 204         spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
 205         if (&cws->list == workqueue_cpu_stat(cpu)->list.next)
 206                 seq_printf(s, "\n");
 207         spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
 208
 209         return 0;
 210 }
 211
 212 static int workqueue_stat_headers(struct seq_file *s)
 213 {
 214         seq_printf(s, "# CPU  INSERTED  EXECUTED   NAME\n");
 215         seq_printf(s, "# |      |         |          |\n\n");
 216         return 0;
 217 }
 218
 219 struct tracer_stat workqueue_stats __read_mostly = {
 220         .name = "workqueues",
 221         .stat_start = workqueue_stat_start,
 222         .stat_next = workqueue_stat_next,
 223         .stat_show = workqueue_stat_show,
 224         .stat_headers = workqueue_stat_headers
 225 };
 226
 227
 228 int __init stat_workqueue_init(void)
 229 {
 230         if (register_stat_tracer(&workqueue_stats)) {
 231                 pr_warning("Unable to register workqueue stat tracer\n");
 232                 return 1;
 233         }
 234
 235         return 0;
 236 }
 237 fs_initcall(stat_workqueue_init);
 238
 239 /*
 240  * Workqueues are created very early, just after pre-smp initcalls.
 241  * So we must register our tracepoints at this stage.
 242  */
 243 int __init trace_workqueue_early_init(void)
 244 {
 245         int ret, cpu;
 246
 247         ret = register_trace_workqueue_insertion(probe_workqueue_insertion);
 248         if (ret)
 249                 goto out;
 250
 251         ret = register_trace_workqueue_execution(probe_workqueue_execution);
 252         if (ret)
 253                 goto no_insertion;
 254
 255         ret = register_trace_workqueue_creation(probe_workqueue_creation);
 256         if (ret)
 257                 goto no_execution;
 258
 259         ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
 260         if (ret)
 261                 goto no_creation;
 262
 263         for_each_possible_cpu(cpu) {
 264                 spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
 265                 INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
 266         }
 267
 268         return 0;
 269
 270 no_creation:
 271         unregister_trace_workqueue_creation(probe_workqueue_creation);
 272 no_execution:
 273         unregister_trace_workqueue_execution(probe_workqueue_execution);
 274 no_insertion:
 275         unregister_trace_workqueue_insertion(probe_workqueue_insertion);
 276 out:
 277         pr_warning("trace_workqueue: unable to trace workqueues\n");
 278
 279         return 1;
 280 }
 281 early_initcall(trace_workqueue_early_init);