1 #ifndef _LTTNG_RING_BUFFER_CONFIG_H
2 #define _LTTNG_RING_BUFFER_CONFIG_H
5 * lttng/ringbuffer-config.h
7 * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 * Ring buffer configuration header. Note: after declaring the standard inline
10 * functions, clients should also include linux/ringbuffer/api.h.
12 * Permission is hereby granted, free of charge, to any person obtaining a copy
13 * of this software and associated documentation files (the "Software"), to deal
14 * in the Software without restriction, including without limitation the rights
15 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
16 * copies of the Software, and to permit persons to whom the Software is
17 * furnished to do so, subject to the following conditions:
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
27 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
32 #include "lttng/ust-tracer.h"
35 #include <urcu/arch.h>
37 #include "lttng/align.h"
38 #include <lttng/ust-compiler.h>
40 struct lttng_ust_lib_ring_buffer
;
42 struct lttng_ust_lib_ring_buffer_config
;
43 struct lttng_ust_lib_ring_buffer_ctx
;
44 struct lttng_ust_shm_handle
;
47 * Ring buffer client callbacks. Only used by slow path, never on fast path.
48 * For the fast path, record_header_size(), ring_buffer_clock_read() should be
49 * provided as inline functions too. These may simply return 0 if not used by
52 struct lttng_ust_lib_ring_buffer_client_cb
{
53 /* Mandatory callbacks */
55 /* A static inline version is also required for fast path */
56 uint64_t (*ring_buffer_clock_read
) (struct channel
*chan
);
57 size_t (*record_header_size
) (const struct lttng_ust_lib_ring_buffer_config
*config
,
58 struct channel
*chan
, size_t offset
,
59 size_t *pre_header_padding
,
60 struct lttng_ust_lib_ring_buffer_ctx
*ctx
);
62 /* Slow path only, at subbuffer switch */
63 size_t (*subbuffer_header_size
) (void);
64 void (*buffer_begin
) (struct lttng_ust_lib_ring_buffer
*buf
, uint64_t tsc
,
65 unsigned int subbuf_idx
,
66 struct lttng_ust_shm_handle
*handle
);
67 void (*buffer_end
) (struct lttng_ust_lib_ring_buffer
*buf
, uint64_t tsc
,
68 unsigned int subbuf_idx
, unsigned long data_size
,
69 struct lttng_ust_shm_handle
*handle
);
71 /* Optional callbacks (can be set to NULL) */
73 /* Called at buffer creation/finalize */
74 int (*buffer_create
) (struct lttng_ust_lib_ring_buffer
*buf
, void *priv
,
75 int cpu
, const char *name
,
76 struct lttng_ust_shm_handle
*handle
);
78 * Clients should guarantee that no new reader handle can be opened
81 void (*buffer_finalize
) (struct lttng_ust_lib_ring_buffer
*buf
,
83 struct lttng_ust_shm_handle
*handle
);
86 * Extract header length, payload length and timestamp from event
87 * record. Used by buffer iterators. Timestamp is only used by channel
90 void (*record_get
) (const struct lttng_ust_lib_ring_buffer_config
*config
,
91 struct channel
*chan
, struct lttng_ust_lib_ring_buffer
*buf
,
92 size_t offset
, size_t *header_len
,
93 size_t *payload_len
, uint64_t *timestamp
,
94 struct lttng_ust_shm_handle
*handle
);
98 * Ring buffer instance configuration.
100 * Declare as "static const" within the client object to ensure the inline fast
101 * paths can be optimized.
105 * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
106 * Per-cpu buffers with per-cpu synchronization. Tracing must be performed
107 * with preemption disabled (lib_ring_buffer_get_cpu() and
108 * lib_ring_buffer_put_cpu()).
110 * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
111 * Per-cpu buffer with global synchronization. Tracing can be performed with
112 * preemption enabled, statistically stays on the local buffers.
114 * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
115 * Should only be used for buffers belonging to a single thread or protected
116 * by mutual exclusion by the client. Note that periodical sub-buffer switch
117 * should be disabled in this kind of configuration.
119 * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
120 * Global shared buffer with global synchronization.
124 * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
125 * buffers and wake up readers if data is ready. Mainly useful for tracers which
126 * don't want to call into the wakeup code on the tracing path. Use in
127 * combination with "read_timer_interval" channel_create() argument.
129 * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
130 * ready to read. Lower latencies before the reader is woken up. Mainly suitable
133 * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
134 * has the responsibility to perform wakeups.
136 #define LTTNG_UST_RING_BUFFER_CONFIG_PADDING 32
138 enum lttng_ust_lib_ring_buffer_alloc_types
{
139 RING_BUFFER_ALLOC_PER_CPU
,
140 RING_BUFFER_ALLOC_GLOBAL
,
143 enum lttng_ust_lib_ring_buffer_sync_types
{
144 RING_BUFFER_SYNC_PER_CPU
, /* Wait-free */
145 RING_BUFFER_SYNC_GLOBAL
, /* Lock-free */
148 enum lttng_ust_lib_ring_buffer_mode_types
{
149 RING_BUFFER_OVERWRITE
, /* Overwrite when buffer full */
150 RING_BUFFER_DISCARD
, /* Discard when buffer full */
153 enum lttng_ust_lib_ring_buffer_output_types
{
156 RING_BUFFER_READ
, /* TODO */
157 RING_BUFFER_ITERATOR
,
161 enum lttng_ust_lib_ring_buffer_backend_types
{
163 RING_BUFFER_VMAP
, /* TODO */
164 RING_BUFFER_STATIC
, /* TODO */
167 enum lttng_ust_lib_ring_buffer_oops_types
{
168 RING_BUFFER_NO_OOPS_CONSISTENCY
,
169 RING_BUFFER_OOPS_CONSISTENCY
,
172 enum lttng_ust_lib_ring_buffer_ipi_types
{
173 RING_BUFFER_IPI_BARRIER
,
174 RING_BUFFER_NO_IPI_BARRIER
,
177 enum lttng_ust_lib_ring_buffer_wakeup_types
{
178 RING_BUFFER_WAKEUP_BY_TIMER
, /* wake up performed by timer */
179 RING_BUFFER_WAKEUP_BY_WRITER
, /*
180 * writer wakes up reader,
186 struct lttng_ust_lib_ring_buffer_config
{
187 enum lttng_ust_lib_ring_buffer_alloc_types alloc
;
188 enum lttng_ust_lib_ring_buffer_sync_types sync
;
189 enum lttng_ust_lib_ring_buffer_mode_types mode
;
190 enum lttng_ust_lib_ring_buffer_output_types output
;
191 enum lttng_ust_lib_ring_buffer_backend_types backend
;
192 enum lttng_ust_lib_ring_buffer_oops_types oops
;
193 enum lttng_ust_lib_ring_buffer_ipi_types ipi
;
194 enum lttng_ust_lib_ring_buffer_wakeup_types wakeup
;
196 * tsc_bits: timestamp bits saved at each record.
197 * 0 and 64 disable the timestamp compression scheme.
199 unsigned int tsc_bits
;
200 struct lttng_ust_lib_ring_buffer_client_cb cb
;
202 * client_type is used by the consumer process (which is in a
203 * different address space) to lookup the appropriate client
204 * callbacks and update the cb pointers.
207 char padding
[LTTNG_UST_RING_BUFFER_CONFIG_PADDING
];
211 * ring buffer context
213 * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
214 * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
215 * lib_ring_buffer_write().
217 * IMPORTANT: this structure is part of the ABI between the probe and
218 * UST. Fields need to be only added at the end, never reordered, never
221 #define LTTNG_UST_RING_BUFFER_CTX_PADDING 24
222 struct lttng_ust_lib_ring_buffer_ctx
{
223 /* input received by lib_ring_buffer_reserve(), saved here. */
224 struct channel
*chan
; /* channel */
225 void *priv
; /* client private data */
226 struct lttng_ust_shm_handle
*handle
; /* shared-memory handle */
227 size_t data_size
; /* size of payload */
228 int largest_align
; /*
229 * alignment of the largest element
232 int cpu
; /* processor id */
234 /* output from lib_ring_buffer_reserve() */
235 struct lttng_ust_lib_ring_buffer
*buf
; /*
236 * buffer corresponding to processor id
239 size_t slot_size
; /* size of the reserved slot */
240 unsigned long buf_offset
; /* offset following the record header */
241 unsigned long pre_offset
; /*
242 * Initial offset position _before_
243 * the record is written. Positioned
244 * prior to record header alignment
247 uint64_t tsc
; /* time-stamp counter value */
248 unsigned int rflags
; /* reservation flags */
249 char padding
[LTTNG_UST_RING_BUFFER_CTX_PADDING
];
253 * lib_ring_buffer_ctx_init - initialize ring buffer context
254 * @ctx: ring buffer context to initialize
256 * @priv: client private data
257 * @data_size: size of record data payload
258 * @largest_align: largest alignment within data payload types
261 static inline lttng_ust_notrace
262 void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
263 struct channel
*chan
, void *priv
,
264 size_t data_size
, int largest_align
,
265 int cpu
, struct lttng_ust_shm_handle
*handle
);
267 void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
268 struct channel
*chan
, void *priv
,
269 size_t data_size
, int largest_align
,
270 int cpu
, struct lttng_ust_shm_handle
*handle
)
274 ctx
->data_size
= data_size
;
275 ctx
->largest_align
= largest_align
;
278 ctx
->handle
= handle
;
279 memset(ctx
->padding
, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING
);
285 * RING_BUFFER_RFLAG_FULL_TSC
287 * This flag is passed to record_header_size() and to the primitive used to
288 * write the record header. It indicates that the full 64-bit time value is
289 * needed in the record header. If this flag is not set, the record header needs
290 * only to contain "tsc_bits" bit of time value.
292 * Reservation flags can be added by the client, starting from
293 * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
294 * record_header_size() to lib_ring_buffer_write_record_header().
296 #define RING_BUFFER_RFLAG_FULL_TSC (1U << 0)
297 #define RING_BUFFER_RFLAG_END (1U << 1)
300 * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
301 * compile-time. We have to duplicate the "config->align" information and the
302 * definition here because config->align is used both in the slow and fast
303 * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
305 #ifdef RING_BUFFER_ALIGN
307 # define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
310 * Calculate the offset needed to align the type.
311 * size_of_type must be non-zero.
313 static inline lttng_ust_notrace
314 unsigned int lib_ring_buffer_align(size_t align_drift
, size_t size_of_type
);
316 unsigned int lib_ring_buffer_align(size_t align_drift
, size_t size_of_type
)
318 return offset_align(align_drift
, size_of_type
);
323 # define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
326 * Calculate the offset needed to align the type.
327 * size_of_type must be non-zero.
329 static inline lttng_ust_notrace
330 unsigned int lib_ring_buffer_align(size_t align_drift
, size_t size_of_type
);
332 unsigned int lib_ring_buffer_align(size_t align_drift
, size_t size_of_type
)
340 * lib_ring_buffer_align_ctx - Align context offset on "alignment"
341 * @ctx: ring buffer context.
343 static inline lttng_ust_notrace
344 void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
347 void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
350 ctx
->buf_offset
+= lib_ring_buffer_align(ctx
->buf_offset
,
355 * lib_ring_buffer_check_config() returns 0 on success.
356 * Used internally to check for valid configurations at channel creation.
358 static inline lttng_ust_notrace
359 int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config
*config
,
360 unsigned int switch_timer_interval
,
361 unsigned int read_timer_interval
);
363 int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config
*config
,
364 unsigned int switch_timer_interval
,
365 unsigned int read_timer_interval
)
367 if (config
->alloc
== RING_BUFFER_ALLOC_GLOBAL
368 && config
->sync
== RING_BUFFER_SYNC_PER_CPU
369 && switch_timer_interval
)
374 #endif /* _LTTNG_RING_BUFFER_CONFIG_H */