lttng-context-perf-counters.c

   1 /*
   2  * (C) Copyright        2009-2011 -
   3  *              Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * LTTng performance monitoring counters (perf-counters) integration module.
   6  *
   7  * Dual LGPL v2.1/GPL v2 license.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/perf_event.h>
  13 #include <linux/list.h>
  14 #include <linux/string.h>
  15 #include "ltt-events.h"
  16 #include "wrapper/ringbuffer/frontend_types.h"
  17 #include "wrapper/vmalloc.h"
  18 #include "ltt-tracer.h"
  19
  20 static
  21 size_t perf_counter_get_size(size_t offset)
  22 {
  23         size_t size = 0;
  24
  25         size += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
  26         size += sizeof(uint64_t);
  27         return size;
  28 }
  29
  30 static
  31 void perf_counter_record(struct lttng_ctx_field *field,
  32                          struct lib_ring_buffer_ctx *ctx,
  33                          struct ltt_channel *chan)
  34 {
  35         struct perf_event *event;
  36         uint64_t value;
  37
  38         event = field->u.perf_counter.e[ctx->cpu];
  39         event->pmu->read(event);
  40         value = local64_read(&event->count);
  41         lib_ring_buffer_align_ctx(ctx, ltt_alignof(value));
  42         chan->ops->event_write(ctx, &value, sizeof(value));
  43 }
  44
  45 static
  46 void overflow_callback(struct perf_event *event, int nmi,
  47                        struct perf_sample_data *data,
  48                        struct pt_regs *regs)
  49 {
  50 }
  51
  52 static
  53 void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field)
  54 {
  55         struct perf_event **events = field->u.perf_counter.e;
  56         int cpu;
  57
  58         get_online_cpus();
  59         for_each_online_cpu(cpu)
  60                 perf_event_release_kernel(events[cpu]);
  61         put_online_cpus();
  62 #ifdef CONFIG_HOTPLUG_CPU
  63         unregister_cpu_notifier(&field->u.perf_counter.nb);
  64 #endif
  65         kfree(field->event_field.name);
  66         kfree(field->u.perf_counter.attr);
  67         kfree(events);
  68 }
  69
  70 #ifdef CONFIG_HOTPLUG_CPU
  71
  72 /**
  73  *      lttng_perf_counter_hp_callback - CPU hotplug callback
  74  *      @nb: notifier block
  75  *      @action: hotplug action to take
  76  *      @hcpu: CPU number
  77  *
  78  *      Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
  79  *
  80  * We can setup perf counters when the cpu is online (up prepare seems to be too
  81  * soon).
  82  */
  83 static
  84 int __cpuinit lttng_perf_counter_cpu_hp_callback(struct notifier_block *nb,
  85                                                  unsigned long action,
  86                                                  void *hcpu)
  87 {
  88         unsigned int cpu = (unsigned long) hcpu;
  89         struct lttng_ctx_field *field =
  90                 container_of(nb, struct lttng_ctx_field, u.perf_counter.nb);
  91         struct perf_event **events = field->u.perf_counter.e;
  92         struct perf_event_attr *attr = field->u.perf_counter.attr;
  93
  94
  95         if (!field->u.perf_counter.hp_enable)
  96                 return NOTIFY_OK;
  97
  98         switch (action) {
  99         case CPU_ONLINE:
 100         case CPU_ONLINE_FROZEN:
 101                 events[cpu] = perf_event_create_kernel_counter(attr,
 102                                 cpu, NULL, overflow_callback);
 103                 if (!events[cpu])
 104                         return NOTIFY_BAD;
 105                 break;
 106         case CPU_UP_CANCELED:
 107         case CPU_UP_CANCELED_FROZEN:
 108         case CPU_DEAD:
 109         case CPU_DEAD_FROZEN:
 110                 perf_event_release_kernel(events[cpu]);
 111                 break;
 112         }
 113         return NOTIFY_OK;
 114 }
 115
 116 #endif
 117
 118 int lttng_add_perf_counter_to_ctx(uint32_t type,
 119                                   uint64_t config,
 120                                   const char *name,
 121                                   struct lttng_ctx **ctx)
 122 {
 123         struct lttng_ctx_field *field;
 124         struct perf_event **events;
 125         struct perf_event_attr *attr;
 126         int ret;
 127         int cpu;
 128         char *name_alloc;
 129
 130         events = kzalloc(num_possible_cpus() * sizeof(*events), GFP_KERNEL);
 131         if (!events)
 132                 return -ENOMEM;
 133
 134         attr = kzalloc(sizeof(*field->u.perf_counter.attr), GFP_KERNEL);
 135         if (!attr) {
 136                 ret = -ENOMEM;
 137                 goto error_attr;
 138         }
 139
 140         attr->type = type;
 141         attr->config = config;
 142         attr->size = sizeof(struct perf_event_attr);
 143         attr->pinned = 1;
 144         attr->disabled = 0;
 145
 146         name_alloc = kstrdup(name, GFP_KERNEL);
 147         if (!name_alloc) {
 148                 ret = -ENOMEM;
 149                 goto name_alloc_error;
 150         }
 151
 152         field = lttng_append_context(ctx);
 153         if (!field) {
 154                 ret = -ENOMEM;
 155                 goto append_context_error;
 156         }
 157
 158 #ifdef CONFIG_HOTPLUG_CPU
 159         field->u.perf_counter.nb.notifier_call =
 160                 lttng_perf_counter_cpu_hp_callback;
 161         field->u.perf_counter.nb.priority = 0;
 162         register_cpu_notifier(&field->u.perf_counter.nb);
 163 #endif
 164
 165         get_online_cpus();
 166         for_each_online_cpu(cpu) {
 167                 events[cpu] = perf_event_create_kernel_counter(attr,
 168                                         cpu, NULL, overflow_callback);
 169                 if (!events[cpu]) {
 170                         ret = -EINVAL;
 171                         goto counter_error;
 172                 }
 173         }
 174         put_online_cpus();
 175
 176         field->destroy = lttng_destroy_perf_counter_field;
 177
 178         field->event_field.name = name_alloc;
 179         field->event_field.type.atype = atype_integer;
 180         field->event_field.type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
 181         field->event_field.type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
 182         field->event_field.type.u.basic.integer.signedness = is_signed_type(unsigned long);
 183         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
 184         field->event_field.type.u.basic.integer.base = 10;
 185         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
 186         field->get_size = perf_counter_get_size;
 187         field->record = perf_counter_record;
 188         field->u.perf_counter.e = events;
 189         field->u.perf_counter.attr = attr;
 190         field->u.perf_counter.hp_enable = 1;
 191
 192         wrapper_vmalloc_sync_all();
 193         return 0;
 194
 195 counter_error:
 196         for_each_online_cpu(cpu) {
 197                 if (events[cpu])
 198                         perf_event_release_kernel(events[cpu]);
 199         }
 200         put_online_cpus();
 201 #ifdef CONFIG_HOTPLUG_CPU
 202         unregister_cpu_notifier(&field->u.perf_counter.nb);
 203 #endif
 204         lttng_remove_context_field(ctx, field);
 205 append_context_error:
 206         kfree(name_alloc);
 207 name_alloc_error:
 208         kfree(attr);
 209 error_attr:
 210         kfree(events);
 211         return ret;
 212 }
 213
 214 MODULE_LICENSE("GPL and additional rights");
 215 MODULE_AUTHOR("Mathieu Desnoyers");
 216 MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support");