lttng-context-perf-counters.c

   1 /*
   2  * lttng-context-perf-counters.c
   3  *
   4  * LTTng performance monitoring counters (perf-counters) integration module.
   5  *
   6  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/perf_event.h>
  26 #include <linux/list.h>
  27 #include <linux/string.h>
  28 #include <linux/cpu.h>
  29 #include "lttng-events.h"
  30 #include "wrapper/ringbuffer/frontend_types.h"
  31 #include "wrapper/vmalloc.h"
  32 #include "wrapper/perf.h"
  33 #include "lttng-tracer.h"
  34
  35 static
  36 size_t perf_counter_get_size(size_t offset)
  37 {
  38         size_t size = 0;
  39
  40         size += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
  41         size += sizeof(uint64_t);
  42         return size;
  43 }
  44
  45 static
  46 void perf_counter_record(struct lttng_ctx_field *field,
  47                          struct lib_ring_buffer_ctx *ctx,
  48                          struct lttng_channel *chan)
  49 {
  50         struct perf_event *event;
  51         uint64_t value;
  52
  53         event = field->u.perf_counter->e[ctx->cpu];
  54         if (likely(event)) {
  55                 if (unlikely(event->state == PERF_EVENT_STATE_ERROR)) {
  56                         value = 0;
  57                 } else {
  58                         event->pmu->read(event);
  59                         value = local64_read(&event->count);
  60                 }
  61         } else {
  62                 /*
  63                  * Perf chooses not to be clever and not to support enabling a
  64                  * perf counter before the cpu is brought up. Therefore, we need
  65                  * to support having events coming (e.g. scheduler events)
  66                  * before the counter is setup. Write an arbitrary 0 in this
  67                  * case.
  68                  */
  69                 value = 0;
  70         }
  71         lib_ring_buffer_align_ctx(ctx, lttng_alignof(value));
  72         chan->ops->event_write(ctx, &value, sizeof(value));
  73 }
  74
  75 #if defined(CONFIG_PERF_EVENTS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,0,99))
  76 static
  77 void overflow_callback(struct perf_event *event,
  78                        struct perf_sample_data *data,
  79                        struct pt_regs *regs)
  80 {
  81 }
  82 #else
  83 static
  84 void overflow_callback(struct perf_event *event, int nmi,
  85                        struct perf_sample_data *data,
  86                        struct pt_regs *regs)
  87 {
  88 }
  89 #endif
  90
  91 static
  92 void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field)
  93 {
  94         struct perf_event **events = field->u.perf_counter->e;
  95         int cpu;
  96
  97         get_online_cpus();
  98         for_each_online_cpu(cpu)
  99                 perf_event_release_kernel(events[cpu]);
 100         put_online_cpus();
 101 #ifdef CONFIG_HOTPLUG_CPU
 102         unregister_cpu_notifier(&field->u.perf_counter->nb);
 103 #endif
 104         kfree(field->event_field.name);
 105         kfree(field->u.perf_counter->attr);
 106         kfree(events);
 107         kfree(field->u.perf_counter);
 108 }
 109
 110 #ifdef CONFIG_HOTPLUG_CPU
 111
 112 /**
 113  *      lttng_perf_counter_hp_callback - CPU hotplug callback
 114  *      @nb: notifier block
 115  *      @action: hotplug action to take
 116  *      @hcpu: CPU number
 117  *
 118  *      Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
 119  *
 120  * We can setup perf counters when the cpu is online (up prepare seems to be too
 121  * soon).
 122  */
 123 static
 124 int lttng_perf_counter_cpu_hp_callback(struct notifier_block *nb,
 125                                                  unsigned long action,
 126                                                  void *hcpu)
 127 {
 128         unsigned int cpu = (unsigned long) hcpu;
 129         struct lttng_perf_counter_field *perf_field =
 130                 container_of(nb, struct lttng_perf_counter_field, nb);
 131         struct perf_event **events = perf_field->e;
 132         struct perf_event_attr *attr = perf_field->attr;
 133         struct perf_event *pevent;
 134
 135         if (!perf_field->hp_enable)
 136                 return NOTIFY_OK;
 137
 138         switch (action) {
 139         case CPU_ONLINE:
 140         case CPU_ONLINE_FROZEN:
 141                 pevent = wrapper_perf_event_create_kernel_counter(attr,
 142                                 cpu, NULL, overflow_callback);
 143                 if (!pevent || IS_ERR(pevent))
 144                         return NOTIFY_BAD;
 145                 if (pevent->state == PERF_EVENT_STATE_ERROR) {
 146                         perf_event_release_kernel(pevent);
 147                         return NOTIFY_BAD;
 148                 }
 149                 barrier();      /* Create perf counter before setting event */
 150                 events[cpu] = pevent;
 151                 break;
 152         case CPU_UP_CANCELED:
 153         case CPU_UP_CANCELED_FROZEN:
 154         case CPU_DEAD:
 155         case CPU_DEAD_FROZEN:
 156                 pevent = events[cpu];
 157                 events[cpu] = NULL;
 158                 barrier();      /* NULLify event before perf counter teardown */
 159                 perf_event_release_kernel(pevent);
 160                 break;
 161         }
 162         return NOTIFY_OK;
 163 }
 164
 165 #endif
 166
 167 int lttng_add_perf_counter_to_ctx(uint32_t type,
 168                                   uint64_t config,
 169                                   const char *name,
 170                                   struct lttng_ctx **ctx)
 171 {
 172         struct lttng_ctx_field *field;
 173         struct lttng_perf_counter_field *perf_field;
 174         struct perf_event **events;
 175         struct perf_event_attr *attr;
 176         int ret;
 177         int cpu;
 178         char *name_alloc;
 179
 180         events = kzalloc(num_possible_cpus() * sizeof(*events), GFP_KERNEL);
 181         if (!events)
 182                 return -ENOMEM;
 183
 184         attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL);
 185         if (!attr) {
 186                 ret = -ENOMEM;
 187                 goto error_attr;
 188         }
 189
 190         attr->type = type;
 191         attr->config = config;
 192         attr->size = sizeof(struct perf_event_attr);
 193         attr->pinned = 1;
 194         attr->disabled = 0;
 195
 196         perf_field = kzalloc(sizeof(struct lttng_perf_counter_field), GFP_KERNEL);
 197         if (!perf_field) {
 198                 ret = -ENOMEM;
 199                 goto error_alloc_perf_field;
 200         }
 201         perf_field->e = events;
 202         perf_field->attr = attr;
 203
 204         name_alloc = kstrdup(name, GFP_KERNEL);
 205         if (!name_alloc) {
 206                 ret = -ENOMEM;
 207                 goto name_alloc_error;
 208         }
 209
 210         field = lttng_append_context(ctx);
 211         if (!field) {
 212                 ret = -ENOMEM;
 213                 goto append_context_error;
 214         }
 215         if (lttng_find_context(*ctx, name_alloc)) {
 216                 ret = -EEXIST;
 217                 goto find_error;
 218         }
 219
 220 #ifdef CONFIG_HOTPLUG_CPU
 221         perf_field->nb.notifier_call =
 222                 lttng_perf_counter_cpu_hp_callback;
 223         perf_field->nb.priority = 0;
 224         register_cpu_notifier(&perf_field->nb);
 225 #endif
 226
 227         get_online_cpus();
 228         for_each_online_cpu(cpu) {
 229                 events[cpu] = wrapper_perf_event_create_kernel_counter(attr,
 230                                         cpu, NULL, overflow_callback);
 231                 if (!events[cpu] || IS_ERR(events[cpu])) {
 232                         ret = -EINVAL;
 233                         goto counter_error;
 234                 }
 235                 if (events[cpu]->state == PERF_EVENT_STATE_ERROR) {
 236                         ret = -EBUSY;
 237                         goto counter_busy;
 238                 }
 239         }
 240         put_online_cpus();
 241
 242         field->destroy = lttng_destroy_perf_counter_field;
 243
 244         field->event_field.name = name_alloc;
 245         field->event_field.type.atype = atype_integer;
 246         field->event_field.type.u.basic.integer.size = sizeof(uint64_t) * CHAR_BIT;
 247         field->event_field.type.u.basic.integer.alignment = lttng_alignof(uint64_t) * CHAR_BIT;
 248         field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(uint64_t);
 249         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
 250         field->event_field.type.u.basic.integer.base = 10;
 251         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
 252         field->get_size = perf_counter_get_size;
 253         field->record = perf_counter_record;
 254         field->u.perf_counter = perf_field;
 255         perf_field->hp_enable = 1;
 256         lttng_context_update(*ctx);
 257
 258         wrapper_vmalloc_sync_all();
 259         return 0;
 260
 261 counter_busy:
 262 counter_error:
 263         for_each_online_cpu(cpu) {
 264                 if (events[cpu] && !IS_ERR(events[cpu]))
 265                         perf_event_release_kernel(events[cpu]);
 266         }
 267         put_online_cpus();
 268 #ifdef CONFIG_HOTPLUG_CPU
 269         unregister_cpu_notifier(&perf_field->nb);
 270 #endif
 271 find_error:
 272         lttng_remove_context_field(ctx, field);
 273 append_context_error:
 274         kfree(name_alloc);
 275 name_alloc_error:
 276         kfree(perf_field);
 277 error_alloc_perf_field:
 278         kfree(attr);
 279 error_attr:
 280         kfree(events);
 281         return ret;
 282 }