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