2 * lttng-context-perf-counters.c
4 * LTTng performance monitoring counters (perf-counters) integration module.
6 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
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"
36 size_t perf_counter_get_size(size_t offset)
40 size += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
41 size += sizeof(uint64_t);
46 void perf_counter_record(struct lttng_ctx_field *field,
47 struct lib_ring_buffer_ctx *ctx,
48 struct lttng_channel *chan)
50 struct perf_event *event;
53 event = field->u.perf_counter->e[ctx->cpu];
55 if (unlikely(event->state == PERF_EVENT_STATE_ERROR)) {
58 event->pmu->read(event);
59 value = local64_read(&event->count);
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
71 lib_ring_buffer_align_ctx(ctx, lttng_alignof(value));
72 chan->ops->event_write(ctx, &value, sizeof(value));
75 #if defined(CONFIG_PERF_EVENTS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,0,99))
77 void overflow_callback(struct perf_event *event,
78 struct perf_sample_data *data,
84 void overflow_callback(struct perf_event *event, int nmi,
85 struct perf_sample_data *data,
92 void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field)
94 struct perf_event **events = field->u.perf_counter->e;
98 for_each_online_cpu(cpu)
99 perf_event_release_kernel(events[cpu]);
101 #ifdef CONFIG_HOTPLUG_CPU
102 unregister_cpu_notifier(&field->u.perf_counter->nb);
104 kfree(field->event_field.name);
105 kfree(field->u.perf_counter->attr);
107 kfree(field->u.perf_counter);
110 #ifdef CONFIG_HOTPLUG_CPU
113 * lttng_perf_counter_hp_callback - CPU hotplug callback
114 * @nb: notifier block
115 * @action: hotplug action to take
118 * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
120 * We can setup perf counters when the cpu is online (up prepare seems to be too
124 int lttng_perf_counter_cpu_hp_callback(struct notifier_block *nb,
125 unsigned long action,
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;
135 if (!perf_field->hp_enable)
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))
145 if (pevent->state == PERF_EVENT_STATE_ERROR) {
146 perf_event_release_kernel(pevent);
149 barrier(); /* Create perf counter before setting event */
150 events[cpu] = pevent;
152 case CPU_UP_CANCELED:
153 case CPU_UP_CANCELED_FROZEN:
155 case CPU_DEAD_FROZEN:
156 pevent = events[cpu];
158 barrier(); /* NULLify event before perf counter teardown */
159 perf_event_release_kernel(pevent);
167 int lttng_add_perf_counter_to_ctx(uint32_t type,
170 struct lttng_ctx **ctx)
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;
180 events = kzalloc(num_possible_cpus() * sizeof(*events), GFP_KERNEL);
184 attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL);
191 attr->config = config;
192 attr->size = sizeof(struct perf_event_attr);
196 perf_field = kzalloc(sizeof(struct lttng_perf_counter_field), GFP_KERNEL);
199 goto error_alloc_perf_field;
201 perf_field->e = events;
202 perf_field->attr = attr;
204 name_alloc = kstrdup(name, GFP_KERNEL);
207 goto name_alloc_error;
210 field = lttng_append_context(ctx);
213 goto append_context_error;
215 if (lttng_find_context(*ctx, name_alloc)) {
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);
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])) {
235 if (events[cpu]->state == PERF_EVENT_STATE_ERROR) {
242 field->destroy = lttng_destroy_perf_counter_field;
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;
257 wrapper_vmalloc_sync_all();
262 for_each_online_cpu(cpu) {
263 if (events[cpu] && !IS_ERR(events[cpu]))
264 perf_event_release_kernel(events[cpu]);
267 #ifdef CONFIG_HOTPLUG_CPU
268 unregister_cpu_notifier(&perf_field->nb);
271 lttng_remove_context_field(ctx, field);
272 append_context_error:
276 error_alloc_perf_field:
283 MODULE_LICENSE("GPL and additional rights");
284 MODULE_AUTHOR("Mathieu Desnoyers");
285 MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support");