2 * ltt-ring-buffer-client.h
4 * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * LTTng lib ring buffer client template.
8 * Dual LGPL v2.1/GPL v2 license.
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include "lib/bitfield.h"
14 #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
15 #include "wrapper/trace-clock.h"
16 #include "ltt-events.h"
17 #include "ltt-tracer.h"
18 #include "wrapper/ringbuffer/frontend_types.h"
21 * Keep the natural field alignment for _each field_ within this structure if
22 * you ever add/remove a field from this header. Packed attribute is not used
23 * because gcc generates poor code on at least powerpc and mips. Don't ever
24 * let gcc add padding between the structure elements.
26 * The guarantee we have with timestamps is that all the events in a
27 * packet are included (inclusive) within the begin/end timestamps of
28 * the packet. Another guarantee we have is that the "timestamp begin",
29 * as well as the event timestamps, are monotonically increasing (never
30 * decrease) when moving forward in a stream (physically). But this
31 * guarantee does not apply to "timestamp end", because it is sampled at
32 * commit time, which is not ordered with respect to space reservation.
35 struct packet_header {
36 /* Trace packet header */
39 * contains endianness information.
45 /* Stream packet context */
46 uint64_t timestamp_begin; /* Cycle count at subbuffer start */
47 uint64_t timestamp_end; /* Cycle count at subbuffer end */
48 uint32_t events_discarded; /*
49 * Events lost in this subbuffer since
50 * the beginning of the trace.
53 uint32_t content_size; /* Size of data in subbuffer */
54 uint32_t packet_size; /* Subbuffer size (include padding) */
55 uint32_t cpu_id; /* CPU id associated with stream */
56 uint8_t header_end; /* End of header */
61 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
63 return trace_clock_read64();
67 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
70 size_t orig_offset = offset;
74 for (i = 0; i < ctx->nr_fields; i++)
75 offset += ctx->fields[i].get_size(offset);
76 return offset - orig_offset;
80 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
81 struct ltt_channel *chan,
82 struct lttng_ctx *ctx)
88 for (i = 0; i < ctx->nr_fields; i++)
89 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
93 * record_header_size - Calculate the header size and padding necessary.
94 * @config: ring buffer instance configuration
96 * @offset: offset in the write buffer
97 * @pre_header_padding: padding to add before the header (output)
98 * @ctx: reservation context
100 * Returns the event header size (including padding).
102 * The payload must itself determine its own alignment from the biggest type it
106 unsigned char record_header_size(const struct lib_ring_buffer_config *config,
107 struct channel *chan, size_t offset,
108 size_t *pre_header_padding,
109 struct lib_ring_buffer_ctx *ctx)
111 struct ltt_channel *ltt_chan = channel_get_private(chan);
112 struct ltt_event *event = ctx->priv;
113 size_t orig_offset = offset;
116 switch (ltt_chan->header_type) {
117 case 1: /* compact */
118 padding = lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
120 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
121 offset += sizeof(uint32_t); /* id and timestamp */
123 /* Minimum space taken by 5-bit id */
124 offset += sizeof(uint8_t);
125 /* Align extended struct on largest member */
126 offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
127 offset += sizeof(uint32_t); /* id */
128 offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
129 offset += sizeof(uint64_t); /* timestamp */
133 padding = lib_ring_buffer_align(offset, ltt_alignof(uint16_t));
135 offset += sizeof(uint16_t);
136 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
137 offset += lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
138 offset += sizeof(uint32_t); /* timestamp */
140 /* Align extended struct on largest member */
141 offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
142 offset += sizeof(uint32_t); /* id */
143 offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
144 offset += sizeof(uint64_t); /* timestamp */
151 offset += ctx_get_size(offset, event->ctx);
152 offset += ctx_get_size(offset, ltt_chan->ctx);
154 *pre_header_padding = padding;
155 return offset - orig_offset;
158 #include "wrapper/ringbuffer/api.h"
161 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
162 struct lib_ring_buffer_ctx *ctx,
166 * ltt_write_event_header
168 * Writes the event header to the offset (already aligned on 32-bits).
170 * @config: ring buffer instance configuration
171 * @ctx: reservation context
172 * @event_id: event ID
175 void ltt_write_event_header(const struct lib_ring_buffer_config *config,
176 struct lib_ring_buffer_ctx *ctx,
179 struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
180 struct ltt_event *event = ctx->priv;
182 if (unlikely(ctx->rflags))
185 switch (ltt_chan->header_type) {
186 case 1: /* compact */
188 uint32_t id_time = 0;
190 bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
191 bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
192 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
197 uint32_t timestamp = (uint32_t) ctx->tsc;
198 uint16_t id = event_id;
200 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
201 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
202 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
209 ctx_record(ctx, ltt_chan, ltt_chan->ctx);
210 ctx_record(ctx, ltt_chan, event->ctx);
211 lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
216 ltt_write_event_header_slow(config, ctx, event_id);
220 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
221 struct lib_ring_buffer_ctx *ctx,
224 struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
225 struct ltt_event *event = ctx->priv;
227 switch (ltt_chan->header_type) {
228 case 1: /* compact */
229 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
230 uint32_t id_time = 0;
232 bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
233 bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
234 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
237 uint64_t timestamp = ctx->tsc;
239 bt_bitfield_write(&id, uint8_t, 0, 5, 31);
240 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
241 /* Align extended struct on largest member */
242 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
243 lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
244 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
245 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
250 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
251 uint32_t timestamp = (uint32_t) ctx->tsc;
252 uint16_t id = event_id;
254 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
255 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
256 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
259 uint64_t timestamp = ctx->tsc;
261 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
262 /* Align extended struct on largest member */
263 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
264 lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
265 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
266 lib_ring_buffer_write(config, ctx, ×tamp, sizeof(timestamp));
273 ctx_record(ctx, ltt_chan, ltt_chan->ctx);
274 ctx_record(ctx, ltt_chan, event->ctx);
275 lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
278 static const struct lib_ring_buffer_config client_config;
280 static u64 client_ring_buffer_clock_read(struct channel *chan)
282 return lib_ring_buffer_clock_read(chan);
286 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
287 struct channel *chan, size_t offset,
288 size_t *pre_header_padding,
289 struct lib_ring_buffer_ctx *ctx)
291 return record_header_size(config, chan, offset,
292 pre_header_padding, ctx);
296 * client_packet_header_size - called on buffer-switch to a new sub-buffer
298 * Return header size without padding after the structure. Don't use packed
299 * structure because gcc generates inefficient code on some architectures
302 static size_t client_packet_header_size(void)
304 return offsetof(struct packet_header, ctx.header_end);
307 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
308 unsigned int subbuf_idx)
310 struct channel *chan = buf->backend.chan;
311 struct packet_header *header =
312 (struct packet_header *)
313 lib_ring_buffer_offset_address(&buf->backend,
314 subbuf_idx * chan->backend.subbuf_size);
315 struct ltt_channel *ltt_chan = channel_get_private(chan);
316 struct ltt_session *session = ltt_chan->session;
318 header->magic = CTF_MAGIC_NUMBER;
319 memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
320 header->stream_id = ltt_chan->id;
321 header->ctx.timestamp_begin = tsc;
322 header->ctx.timestamp_end = 0;
323 header->ctx.events_discarded = 0;
324 header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
325 header->ctx.packet_size = 0xFFFFFFFF;
326 header->ctx.cpu_id = buf->backend.cpu;
330 * offset is assumed to never be 0 here : never deliver a completely empty
331 * subbuffer. data_size is between 1 and subbuf_size.
333 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
334 unsigned int subbuf_idx, unsigned long data_size)
336 struct channel *chan = buf->backend.chan;
337 struct packet_header *header =
338 (struct packet_header *)
339 lib_ring_buffer_offset_address(&buf->backend,
340 subbuf_idx * chan->backend.subbuf_size);
341 unsigned long records_lost = 0;
343 header->ctx.timestamp_end = tsc;
344 header->ctx.content_size = data_size * CHAR_BIT; /* in bits */
345 header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
346 records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
347 records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
348 records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
349 header->ctx.events_discarded = records_lost;
352 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
353 int cpu, const char *name)
358 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
362 static const struct lib_ring_buffer_config client_config = {
363 .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
364 .cb.record_header_size = client_record_header_size,
365 .cb.subbuffer_header_size = client_packet_header_size,
366 .cb.buffer_begin = client_buffer_begin,
367 .cb.buffer_end = client_buffer_end,
368 .cb.buffer_create = client_buffer_create,
369 .cb.buffer_finalize = client_buffer_finalize,
372 .alloc = RING_BUFFER_ALLOC_PER_CPU,
373 .sync = RING_BUFFER_SYNC_PER_CPU,
374 .mode = RING_BUFFER_MODE_TEMPLATE,
375 .backend = RING_BUFFER_PAGE,
376 .output = RING_BUFFER_OUTPUT_TEMPLATE,
377 .oops = RING_BUFFER_OOPS_CONSISTENCY,
378 .ipi = RING_BUFFER_IPI_BARRIER,
379 .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
383 struct channel *_channel_create(const char *name,
384 struct ltt_channel *ltt_chan, void *buf_addr,
385 size_t subbuf_size, size_t num_subbuf,
386 unsigned int switch_timer_interval,
387 unsigned int read_timer_interval)
389 return channel_create(&client_config, name, ltt_chan, buf_addr,
390 subbuf_size, num_subbuf, switch_timer_interval,
391 read_timer_interval);
395 void ltt_channel_destroy(struct channel *chan)
397 channel_destroy(chan);
401 struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
403 struct lib_ring_buffer *buf;
406 for_each_channel_cpu(cpu, chan) {
407 buf = channel_get_ring_buffer(&client_config, chan, cpu);
408 if (!lib_ring_buffer_open_read(buf))
415 int ltt_buffer_has_read_closed_stream(struct channel *chan)
417 struct lib_ring_buffer *buf;
420 for_each_channel_cpu(cpu, chan) {
421 buf = channel_get_ring_buffer(&client_config, chan, cpu);
422 if (!atomic_long_read(&buf->active_readers))
429 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
431 lib_ring_buffer_release_read(buf);
435 int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx,
438 struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
441 cpu = lib_ring_buffer_get_cpu(&client_config);
446 switch (ltt_chan->header_type) {
447 case 1: /* compact */
449 ctx->rflags |= LTT_RFLAG_EXTENDED;
452 if (event_id > 65534)
453 ctx->rflags |= LTT_RFLAG_EXTENDED;
459 ret = lib_ring_buffer_reserve(&client_config, ctx);
462 ltt_write_event_header(&client_config, ctx, event_id);
465 lib_ring_buffer_put_cpu(&client_config);
470 void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
472 lib_ring_buffer_commit(&client_config, ctx);
473 lib_ring_buffer_put_cpu(&client_config);
477 void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
480 lib_ring_buffer_write(&client_config, ctx, src, len);
484 void ltt_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
485 const void __user *src, size_t len)
487 lib_ring_buffer_copy_from_user(&client_config, ctx, src, len);
491 void ltt_event_memset(struct lib_ring_buffer_ctx *ctx,
494 lib_ring_buffer_memset(&client_config, ctx, c, len);
498 wait_queue_head_t *ltt_get_writer_buf_wait_queue(struct channel *chan, int cpu)
500 struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
502 return &buf->write_wait;
506 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
508 return &chan->hp_wait;
512 int ltt_is_finalized(struct channel *chan)
514 return lib_ring_buffer_channel_is_finalized(chan);
518 int ltt_is_disabled(struct channel *chan)
520 return lib_ring_buffer_channel_is_disabled(chan);
523 static struct ltt_transport ltt_relay_transport = {
524 .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
525 .owner = THIS_MODULE,
527 .channel_create = _channel_create,
528 .channel_destroy = ltt_channel_destroy,
529 .buffer_read_open = ltt_buffer_read_open,
530 .buffer_has_read_closed_stream =
531 ltt_buffer_has_read_closed_stream,
532 .buffer_read_close = ltt_buffer_read_close,
533 .event_reserve = ltt_event_reserve,
534 .event_commit = ltt_event_commit,
535 .event_write = ltt_event_write,
536 .event_write_from_user = ltt_event_write_from_user,
537 .event_memset = ltt_event_memset,
538 .packet_avail_size = NULL, /* Would be racy anyway */
539 .get_writer_buf_wait_queue = ltt_get_writer_buf_wait_queue,
540 .get_hp_wait_queue = ltt_get_hp_wait_queue,
541 .is_finalized = ltt_is_finalized,
542 .is_disabled = ltt_is_disabled,
546 static int __init ltt_ring_buffer_client_init(void)
549 * This vmalloc sync all also takes care of the lib ring buffer
550 * vmalloc'd module pages when it is built as a module into LTTng.
552 wrapper_vmalloc_sync_all();
553 ltt_transport_register(<t_relay_transport);
557 module_init(ltt_ring_buffer_client_init);
559 static void __exit ltt_ring_buffer_client_exit(void)
561 ltt_transport_unregister(<t_relay_transport);
564 module_exit(ltt_ring_buffer_client_exit);
566 MODULE_LICENSE("GPL and additional rights");
567 MODULE_AUTHOR("Mathieu Desnoyers");
568 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING