2 * lttng-ring-buffer-client.h
4 * LTTng lib ring buffer client template.
6 * Copyright (C) 2010-2012 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/types.h>
25 #include "lib/bitfield.h"
26 #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
27 #include "wrapper/trace-clock.h"
28 #include "lttng-events.h"
29 #include "lttng-tracer.h"
30 #include "wrapper/ringbuffer/frontend_types.h"
32 #define LTTNG_COMPACT_EVENT_BITS 5
33 #define LTTNG_COMPACT_TSC_BITS 27
36 * Keep the natural field alignment for _each field_ within this structure if
37 * you ever add/remove a field from this header. Packed attribute is not used
38 * because gcc generates poor code on at least powerpc and mips. Don't ever
39 * let gcc add padding between the structure elements.
41 * The guarantee we have with timestamps is that all the events in a
42 * packet are included (inclusive) within the begin/end timestamps of
43 * the packet. Another guarantee we have is that the "timestamp begin",
44 * as well as the event timestamps, are monotonically increasing (never
45 * decrease) when moving forward in a stream (physically). But this
46 * guarantee does not apply to "timestamp end", because it is sampled at
47 * commit time, which is not ordered with respect to space reservation.
50 struct packet_header {
51 /* Trace packet header */
54 * contains endianness information.
60 /* Stream packet context */
61 uint64_t timestamp_begin; /* Cycle count at subbuffer start */
62 uint64_t timestamp_end; /* Cycle count at subbuffer end */
63 uint64_t content_size; /* Size of data in subbuffer */
64 uint64_t packet_size; /* Subbuffer size (include padding) */
65 unsigned long events_discarded; /*
66 * Events lost in this subbuffer since
67 * the beginning of the trace.
70 uint32_t cpu_id; /* CPU id associated with stream */
71 uint8_t header_end; /* End of header */
76 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
78 return trace_clock_read64();
82 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
85 size_t orig_offset = offset;
89 for (i = 0; i < ctx->nr_fields; i++)
90 offset += ctx->fields[i].get_size(offset);
91 return offset - orig_offset;
95 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
96 struct lttng_channel *chan,
97 struct lttng_ctx *ctx)
103 for (i = 0; i < ctx->nr_fields; i++)
104 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
108 * record_header_size - Calculate the header size and padding necessary.
109 * @config: ring buffer instance configuration
111 * @offset: offset in the write buffer
112 * @pre_header_padding: padding to add before the header (output)
113 * @ctx: reservation context
115 * Returns the event header size (including padding).
117 * The payload must itself determine its own alignment from the biggest type it
121 unsigned char record_header_size(const struct lib_ring_buffer_config *config,
122 struct channel *chan, size_t offset,
123 size_t *pre_header_padding,
124 struct lib_ring_buffer_ctx *ctx)
126 struct lttng_channel *lttng_chan = channel_get_private(chan);
127 struct lttng_event *event = ctx->priv;
128 size_t orig_offset = offset;
131 switch (lttng_chan->header_type) {
132 case 1: /* compact */
133 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
135 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
136 offset += sizeof(uint32_t); /* id and timestamp */
138 /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
139 offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
140 /* Align extended struct on largest member */
141 offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
142 offset += sizeof(uint32_t); /* id */
143 offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
144 offset += sizeof(uint64_t); /* timestamp */
148 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
150 offset += sizeof(uint16_t);
151 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
152 offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
153 offset += sizeof(uint32_t); /* timestamp */
155 /* Align extended struct on largest member */
156 offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
157 offset += sizeof(uint32_t); /* id */
158 offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
159 offset += sizeof(uint64_t); /* timestamp */
166 offset += ctx_get_size(offset, event->ctx);
167 offset += ctx_get_size(offset, lttng_chan->ctx);
169 *pre_header_padding = padding;
170 return offset - orig_offset;
173 #include "wrapper/ringbuffer/api.h"
176 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
177 struct lib_ring_buffer_ctx *ctx,
181 * lttng_write_event_header
183 * Writes the event header to the offset (already aligned on 32-bits).
185 * @config: ring buffer instance configuration
186 * @ctx: reservation context
187 * @event_id: event ID
190 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
191 struct lib_ring_buffer_ctx *ctx,
194 struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
195 struct lttng_event *event = ctx->priv;
197 if (unlikely(ctx->rflags))
200 switch (lttng_chan->header_type) {
201 case 1: /* compact */
203 uint32_t id_time = 0;
205 bt_bitfield_write(&id_time, uint32_t,
207 LTTNG_COMPACT_EVENT_BITS,
209 bt_bitfield_write(&id_time, uint32_t,
210 LTTNG_COMPACT_EVENT_BITS,
211 LTTNG_COMPACT_TSC_BITS,
213 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
218 uint32_t timestamp = (uint32_t) ctx->tsc;
219 uint16_t id = event_id;
221 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
222 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
223 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
230 ctx_record(ctx, lttng_chan, lttng_chan->ctx);
231 ctx_record(ctx, lttng_chan, event->ctx);
232 lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
237 lttng_write_event_header_slow(config, ctx, event_id);
241 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
242 struct lib_ring_buffer_ctx *ctx,
245 struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
246 struct lttng_event *event = ctx->priv;
248 switch (lttng_chan->header_type) {
249 case 1: /* compact */
250 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
251 uint32_t id_time = 0;
253 bt_bitfield_write(&id_time, uint32_t,
255 LTTNG_COMPACT_EVENT_BITS,
257 bt_bitfield_write(&id_time, uint32_t,
258 LTTNG_COMPACT_EVENT_BITS,
259 LTTNG_COMPACT_TSC_BITS, ctx->tsc);
260 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
263 uint64_t timestamp = ctx->tsc;
265 bt_bitfield_write(&id, uint8_t,
267 LTTNG_COMPACT_EVENT_BITS,
269 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
270 /* Align extended struct on largest member */
271 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
272 lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
273 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
274 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
279 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
280 uint32_t timestamp = (uint32_t) ctx->tsc;
281 uint16_t id = event_id;
283 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
284 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
285 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
288 uint64_t timestamp = ctx->tsc;
290 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
291 /* Align extended struct on largest member */
292 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
293 lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
294 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
295 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
302 ctx_record(ctx, lttng_chan, lttng_chan->ctx);
303 ctx_record(ctx, lttng_chan, event->ctx);
304 lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
307 static const struct lib_ring_buffer_config client_config;
309 static u64 client_ring_buffer_clock_read(struct channel *chan)
311 return lib_ring_buffer_clock_read(chan);
315 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
316 struct channel *chan, size_t offset,
317 size_t *pre_header_padding,
318 struct lib_ring_buffer_ctx *ctx)
320 return record_header_size(config, chan, offset,
321 pre_header_padding, ctx);
325 * client_packet_header_size - called on buffer-switch to a new sub-buffer
327 * Return header size without padding after the structure. Don't use packed
328 * structure because gcc generates inefficient code on some architectures
331 static size_t client_packet_header_size(void)
333 return offsetof(struct packet_header, ctx.header_end);
336 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
337 unsigned int subbuf_idx)
339 struct channel *chan = buf->backend.chan;
340 struct packet_header *header =
341 (struct packet_header *)
342 lib_ring_buffer_offset_address(&buf->backend,
343 subbuf_idx * chan->backend.subbuf_size);
344 struct lttng_channel *lttng_chan = channel_get_private(chan);
345 struct lttng_session *session = lttng_chan->session;
347 header->magic = CTF_MAGIC_NUMBER;
348 memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
349 header->stream_id = lttng_chan->id;
350 header->ctx.timestamp_begin = tsc;
351 header->ctx.timestamp_end = 0;
352 header->ctx.content_size = ~0ULL; /* for debugging */
353 header->ctx.packet_size = ~0ULL;
354 header->ctx.events_discarded = 0;
355 header->ctx.cpu_id = buf->backend.cpu;
359 * offset is assumed to never be 0 here : never deliver a completely empty
360 * subbuffer. data_size is between 1 and subbuf_size.
362 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
363 unsigned int subbuf_idx, unsigned long data_size)
365 struct channel *chan = buf->backend.chan;
366 struct packet_header *header =
367 (struct packet_header *)
368 lib_ring_buffer_offset_address(&buf->backend,
369 subbuf_idx * chan->backend.subbuf_size);
370 unsigned long records_lost = 0;
372 header->ctx.timestamp_end = tsc;
373 header->ctx.content_size =
374 (uint64_t) data_size * CHAR_BIT; /* in bits */
375 header->ctx.packet_size =
376 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
377 records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
378 records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
379 records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
380 header->ctx.events_discarded = records_lost;
383 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
384 int cpu, const char *name)
389 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
393 static const struct lib_ring_buffer_config client_config = {
394 .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
395 .cb.record_header_size = client_record_header_size,
396 .cb.subbuffer_header_size = client_packet_header_size,
397 .cb.buffer_begin = client_buffer_begin,
398 .cb.buffer_end = client_buffer_end,
399 .cb.buffer_create = client_buffer_create,
400 .cb.buffer_finalize = client_buffer_finalize,
402 .tsc_bits = LTTNG_COMPACT_TSC_BITS,
403 .alloc = RING_BUFFER_ALLOC_PER_CPU,
404 .sync = RING_BUFFER_SYNC_PER_CPU,
405 .mode = RING_BUFFER_MODE_TEMPLATE,
406 .backend = RING_BUFFER_PAGE,
407 .output = RING_BUFFER_OUTPUT_TEMPLATE,
408 .oops = RING_BUFFER_OOPS_CONSISTENCY,
409 .ipi = RING_BUFFER_IPI_BARRIER,
410 .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
414 struct channel *_channel_create(const char *name,
415 struct lttng_channel *lttng_chan, void *buf_addr,
416 size_t subbuf_size, size_t num_subbuf,
417 unsigned int switch_timer_interval,
418 unsigned int read_timer_interval)
420 return channel_create(&client_config, name, lttng_chan, buf_addr,
421 subbuf_size, num_subbuf, switch_timer_interval,
422 read_timer_interval);
426 void lttng_channel_destroy(struct channel *chan)
428 channel_destroy(chan);
432 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
434 struct lib_ring_buffer *buf;
437 for_each_channel_cpu(cpu, chan) {
438 buf = channel_get_ring_buffer(&client_config, chan, cpu);
439 if (!lib_ring_buffer_open_read(buf))
446 int lttng_buffer_has_read_closed_stream(struct channel *chan)
448 struct lib_ring_buffer *buf;
451 for_each_channel_cpu(cpu, chan) {
452 buf = channel_get_ring_buffer(&client_config, chan, cpu);
453 if (!atomic_long_read(&buf->active_readers))
460 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
462 lib_ring_buffer_release_read(buf);
466 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
469 struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
472 cpu = lib_ring_buffer_get_cpu(&client_config);
477 switch (lttng_chan->header_type) {
478 case 1: /* compact */
480 ctx->rflags |= LTTNG_RFLAG_EXTENDED;
483 if (event_id > 65534)
484 ctx->rflags |= LTTNG_RFLAG_EXTENDED;
490 ret = lib_ring_buffer_reserve(&client_config, ctx);
493 lttng_write_event_header(&client_config, ctx, event_id);
496 lib_ring_buffer_put_cpu(&client_config);
501 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
503 lib_ring_buffer_commit(&client_config, ctx);
504 lib_ring_buffer_put_cpu(&client_config);
508 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
511 lib_ring_buffer_write(&client_config, ctx, src, len);
515 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
516 const void __user *src, size_t len)
518 lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
522 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
525 lib_ring_buffer_memset(&client_config, ctx, c, len);
529 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
531 struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
533 return &buf->write_wait;
537 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
539 return &chan->hp_wait;
543 int lttng_is_finalized(struct channel *chan)
545 return lib_ring_buffer_channel_is_finalized(chan);
549 int lttng_is_disabled(struct channel *chan)
551 return lib_ring_buffer_channel_is_disabled(chan);
554 static struct lttng_transport lttng_relay_transport = {
555 .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
556 .owner = THIS_MODULE,
558 .channel_create = _channel_create,
559 .channel_destroy = lttng_channel_destroy,
560 .buffer_read_open = lttng_buffer_read_open,
561 .buffer_has_read_closed_stream =
562 lttng_buffer_has_read_closed_stream,
563 .buffer_read_close = lttng_buffer_read_close,
564 .event_reserve = lttng_event_reserve,
565 .event_commit = lttng_event_commit,
566 .event_write = lttng_event_write,
567 .event_write_from_user = lttng_event_write_from_user,
568 .event_memset = lttng_event_memset,
569 .packet_avail_size = NULL, /* Would be racy anyway */
570 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
571 .get_hp_wait_queue = lttng_get_hp_wait_queue,
572 .is_finalized = lttng_is_finalized,
573 .is_disabled = lttng_is_disabled,
577 static int __init lttng_ring_buffer_client_init(void)
580 * This vmalloc sync all also takes care of the lib ring buffer
581 * vmalloc'd module pages when it is built as a module into LTTng.
583 wrapper_vmalloc_sync_all();
584 lttng_transport_register(<tng_relay_transport);
588 module_init(lttng_ring_buffer_client_init);
590 static void __exit lttng_ring_buffer_client_exit(void)
592 lttng_transport_unregister(<tng_relay_transport);
595 module_exit(lttng_ring_buffer_client_exit);
597 MODULE_LICENSE("GPL and additional rights");
598 MODULE_AUTHOR("Mathieu Desnoyers");
599 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING