[lttng-ust.git] / include / ust / ringbuffer-config.h

#ifndef _LINUX_RING_BUFFER_CONFIG_H
#define _LINUX_RING_BUFFER_CONFIG_H

/*
 * linux/ringbuffer/config.h
 *
 * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Ring buffer configuration header. Note: after declaring the standard inline
 * functions, clients should also include linux/ringbuffer/api.h.
 *
 * Dual LGPL v2.1/GPL v2 license.
 */

#include <errno.h>
#include "ust/kcompat/kcompat.h"
#include "ust/align.h"

struct lib_ring_buffer;
struct channel;
struct lib_ring_buffer_config;
struct lib_ring_buffer_ctx;
struct shm_handle *handle;

/*
 * Ring buffer client callbacks. Only used by slow path, never on fast path.
 * For the fast path, record_header_size(), ring_buffer_clock_read() should be
 * provided as inline functions too.  These may simply return 0 if not used by
 * the client.
 */
struct lib_ring_buffer_client_cb {
	/* Mandatory callbacks */

	/* A static inline version is also required for fast path */
	u64 (*ring_buffer_clock_read) (struct channel *chan);
	size_t (*record_header_size) (const struct lib_ring_buffer_config *config,
				      struct channel *chan, size_t offset,
				      size_t *pre_header_padding,
				      struct lib_ring_buffer_ctx *ctx);

	/* Slow path only, at subbuffer switch */
	size_t (*subbuffer_header_size) (void);
	void (*buffer_begin) (struct lib_ring_buffer *buf, u64 tsc,
			      unsigned int subbuf_idx,
			      struct shm_handle *handle);
	void (*buffer_end) (struct lib_ring_buffer *buf, u64 tsc,
			    unsigned int subbuf_idx, unsigned long data_size,
			    struct shm_handle *handle);

	/* Optional callbacks (can be set to NULL) */

	/* Called at buffer creation/finalize */
	int (*buffer_create) (struct lib_ring_buffer *buf, void *priv,
			      int cpu, const char *name,
			      struct shm_handle *handle);
	/*
	 * Clients should guarantee that no new reader handle can be opened
	 * after finalize.
	 */
	void (*buffer_finalize) (struct lib_ring_buffer *buf,
				 void *priv, int cpu,
				 struct shm_handle *handle);

	/*
	 * Extract header length, payload length and timestamp from event
	 * record. Used by buffer iterators. Timestamp is only used by channel
	 * iterator.
	 */
	void (*record_get) (const struct lib_ring_buffer_config *config,
			    struct channel *chan, struct lib_ring_buffer *buf,
			    size_t offset, size_t *header_len,
			    size_t *payload_len, u64 *timestamp,
			    struct shm_handle *handle);
};

/*
 * Ring buffer instance configuration.
 *
 * Declare as "static const" within the client object to ensure the inline fast
 * paths can be optimized.
 *
 * alloc/sync pairs:
 *
 * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
 *   Per-cpu buffers with per-cpu synchronization. Tracing must be performed
 *   with preemption disabled (lib_ring_buffer_get_cpu() and
 *   lib_ring_buffer_put_cpu()).
 *
 * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
 *   Per-cpu buffer with global synchronization. Tracing can be performed with
 *   preemption enabled, statistically stays on the local buffers.
 *
 * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
 *   Should only be used for buffers belonging to a single thread or protected
 *   by mutual exclusion by the client. Note that periodical sub-buffer switch
 *   should be disabled in this kind of configuration.
 *
 * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
 *   Global shared buffer with global synchronization.
 *
 * wakeup:
 *
 * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
 * buffers and wake up readers if data is ready. Mainly useful for tracers which
 * don't want to call into the wakeup code on the tracing path. Use in
 * combination with "read_timer_interval" channel_create() argument.
 *
 * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
 * ready to read. Lower latencies before the reader is woken up. Mainly suitable
 * for drivers.
 *
 * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
 * has the responsibility to perform wakeups.
 */
struct lib_ring_buffer_config {
	enum {
		RING_BUFFER_ALLOC_PER_CPU,
		RING_BUFFER_ALLOC_GLOBAL,
	} alloc;
	enum {
		RING_BUFFER_SYNC_PER_CPU,	/* Wait-free */
		RING_BUFFER_SYNC_GLOBAL,	/* Lock-free */
	} sync;
	enum {
		RING_BUFFER_OVERWRITE,		/* Overwrite when buffer full */
		RING_BUFFER_DISCARD,		/* Discard when buffer full */
	} mode;
	enum {
		RING_BUFFER_SPLICE,
		RING_BUFFER_MMAP,
		RING_BUFFER_READ,		/* TODO */
		RING_BUFFER_ITERATOR,
		RING_BUFFER_NONE,
	} output;
	enum {
		RING_BUFFER_PAGE,
		RING_BUFFER_VMAP,		/* TODO */
		RING_BUFFER_STATIC,		/* TODO */
	} backend;
	enum {
		RING_BUFFER_NO_OOPS_CONSISTENCY,
		RING_BUFFER_OOPS_CONSISTENCY,
	} oops;
	enum {
		RING_BUFFER_IPI_BARRIER,
		RING_BUFFER_NO_IPI_BARRIER,
	} ipi;
	enum {
		RING_BUFFER_WAKEUP_BY_TIMER,	/* wake up performed by timer */
		RING_BUFFER_WAKEUP_BY_WRITER,	/*
						 * writer wakes up reader,
						 * not lock-free
						 * (takes spinlock).
						 */
	} wakeup;
	/*
	 * tsc_bits: timestamp bits saved at each record.
	 *   0 and 64 disable the timestamp compression scheme.
	 */
	unsigned int tsc_bits;
	struct lib_ring_buffer_client_cb cb;
};

/*
 * ring buffer context
 *
 * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
 * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
 * lib_ring_buffer_write().
 */
struct lib_ring_buffer_ctx {
	/* input received by lib_ring_buffer_reserve(), saved here. */
	struct channel *chan;		/* channel */
	void *priv;			/* client private data */
	struct shm_handle *handle;	/* shared-memory handle */
	size_t data_size;		/* size of payload */
	int largest_align;		/*
					 * alignment of the largest element
					 * in the payload
					 */
	int cpu;			/* processor id */

	/* output from lib_ring_buffer_reserve() */
	struct lib_ring_buffer *buf;	/*
					 * buffer corresponding to processor id
					 * for this channel
					 */
	size_t slot_size;		/* size of the reserved slot */
	unsigned long buf_offset;	/* offset following the record header */
	unsigned long pre_offset;	/*
					 * Initial offset position _before_
					 * the record is written. Positioned
					 * prior to record header alignment
					 * padding.
					 */
	u64 tsc;			/* time-stamp counter value */
	unsigned int rflags;		/* reservation flags */
};

/**
 * lib_ring_buffer_ctx_init - initialize ring buffer context
 * @ctx: ring buffer context to initialize
 * @chan: channel
 * @priv: client private data
 * @data_size: size of record data payload
 * @largest_align: largest alignment within data payload types
 * @cpu: processor id
 */
static inline
void lib_ring_buffer_ctx_init(struct lib_ring_buffer_ctx *ctx,
			      struct channel *chan, void *priv,
			      size_t data_size, int largest_align,
			      int cpu, struct shm_handle *handle)
{
	ctx->chan = chan;
	ctx->priv = priv;
	ctx->data_size = data_size;
	ctx->largest_align = largest_align;
	ctx->cpu = cpu;
	ctx->rflags = 0;
	ctx->handle = handle;
}

/*
 * Reservation flags.
 *
 * RING_BUFFER_RFLAG_FULL_TSC
 *
 * This flag is passed to record_header_size() and to the primitive used to
 * write the record header. It indicates that the full 64-bit time value is
 * needed in the record header. If this flag is not set, the record header needs
 * only to contain "tsc_bits" bit of time value.
 *
 * Reservation flags can be added by the client, starting from
 * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
 * record_header_size() to lib_ring_buffer_write_record_header().
 */
#define	RING_BUFFER_RFLAG_FULL_TSC		(1U << 0)
#define RING_BUFFER_RFLAG_END			(1U << 1)

/*
 * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
 * compile-time. We have to duplicate the "config->align" information and the
 * definition here because config->align is used both in the slow and fast
 * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
 */
#ifdef RING_BUFFER_ALIGN

# define RING_BUFFER_ALIGN_ATTR		/* Default arch alignment */

/*
 * Calculate the offset needed to align the type.
 * size_of_type must be non-zero.
 */
static inline
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
{
	return offset_align(align_drift, size_of_type);
}

#else

# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))

/*
 * Calculate the offset needed to align the type.
 * size_of_type must be non-zero.
 */
static inline
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
{
	return 0;
}

#endif

/**
 * lib_ring_buffer_align_ctx - Align context offset on "alignment"
 * @ctx: ring buffer context.
 */
static inline
void lib_ring_buffer_align_ctx(struct lib_ring_buffer_ctx *ctx,
			   size_t alignment)
{
	ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
						 alignment);
}

/*
 * lib_ring_buffer_check_config() returns 0 on success.
 * Used internally to check for valid configurations at channel creation.
 */
static inline
int lib_ring_buffer_check_config(const struct lib_ring_buffer_config *config,
			     unsigned int switch_timer_interval,
			     unsigned int read_timer_interval)
{
	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
	    && config->sync == RING_BUFFER_SYNC_PER_CPU
	    && switch_timer_interval)
		return -EINVAL;
	return 0;
}

#include <ust/vatomic.h>

#endif /* _LINUX_RING_BUFFER_CONFIG_H */
Commit	Line	Data
a6352fd4 MD	1	#ifndef _LINUX_RING_BUFFER_CONFIG_H
	2	#define _LINUX_RING_BUFFER_CONFIG_H
	3
	4	/*
	5	* linux/ringbuffer/config.h
	6	*
	7	* Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* Ring buffer configuration header. Note: after declaring the standard inline
	10	* functions, clients should also include linux/ringbuffer/api.h.
	11	*
	12	* Dual LGPL v2.1/GPL v2 license.
	13	*/
	14
	15	#include <errno.h>
	16	#include "ust/kcompat/kcompat.h"
	17	#include "ust/align.h"
	18
	19	struct lib_ring_buffer;
	20	struct channel;
	21	struct lib_ring_buffer_config;
	22	struct lib_ring_buffer_ctx;
1d498196	23	struct shm_handle *handle;
a6352fd4 MD	24
	25	/*
	26	* Ring buffer client callbacks. Only used by slow path, never on fast path.
	27	* For the fast path, record_header_size(), ring_buffer_clock_read() should be
	28	* provided as inline functions too. These may simply return 0 if not used by
	29	* the client.
	30	*/
	31	struct lib_ring_buffer_client_cb {
	32	/* Mandatory callbacks */
	33
	34	/* A static inline version is also required for fast path */
	35	u64 (ring_buffer_clock_read) (struct channel chan);
	36	size_t (record_header_size) (const struct lib_ring_buffer_config config,
	37	struct channel *chan, size_t offset,
	38	size_t *pre_header_padding,
	39	struct lib_ring_buffer_ctx *ctx);
	40
	41	/* Slow path only, at subbuffer switch */
	42	size_t (*subbuffer_header_size) (void);
	43	void (buffer_begin) (struct lib_ring_buffer buf, u64 tsc,
1d498196 MD	44	unsigned int subbuf_idx,
1d498196 MD	45	struct shm_handle *handle);
a6352fd4	46	void (buffer_end) (struct lib_ring_buffer buf, u64 tsc,
1d498196 MD	47	unsigned int subbuf_idx, unsigned long data_size,
1d498196 MD	48	struct shm_handle *handle);
a6352fd4 MD	49
	50	/* Optional callbacks (can be set to NULL) */
	51
	52	/* Called at buffer creation/finalize */
	53	int (buffer_create) (struct lib_ring_buffer buf, void *priv,
1d498196 MD	54	int cpu, const char *name,
1d498196 MD	55	struct shm_handle *handle);
a6352fd4 MD	56	/*
	57	* Clients should guarantee that no new reader handle can be opened
	58	* after finalize.
	59	*/
1d498196 MD	60	void (buffer_finalize) (struct lib_ring_buffer buf,
	61	void *priv, int cpu,
	62	struct shm_handle *handle);
a6352fd4 MD	63
	64	/*
	65	* Extract header length, payload length and timestamp from event
	66	* record. Used by buffer iterators. Timestamp is only used by channel
	67	* iterator.
	68	*/
	69	void (record_get) (const struct lib_ring_buffer_config config,
	70	struct channel chan, struct lib_ring_buffer buf,
	71	size_t offset, size_t *header_len,
1d498196 MD	72	size_t payload_len, u64 timestamp,
1d498196 MD	73	struct shm_handle *handle);
a6352fd4 MD	74	};
	75
	76	/*
	77	* Ring buffer instance configuration.
	78	*
	79	* Declare as "static const" within the client object to ensure the inline fast
	80	* paths can be optimized.
	81	*
	82	* alloc/sync pairs:
	83	*
	84	* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
	85	* Per-cpu buffers with per-cpu synchronization. Tracing must be performed
	86	* with preemption disabled (lib_ring_buffer_get_cpu() and
	87	* lib_ring_buffer_put_cpu()).
	88	*
	89	* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
	90	* Per-cpu buffer with global synchronization. Tracing can be performed with
	91	* preemption enabled, statistically stays on the local buffers.
	92	*
	93	* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
	94	* Should only be used for buffers belonging to a single thread or protected
	95	* by mutual exclusion by the client. Note that periodical sub-buffer switch
	96	* should be disabled in this kind of configuration.
	97	*
	98	* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
	99	* Global shared buffer with global synchronization.
	100	*
	101	* wakeup:
	102	*
	103	* RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
	104	* buffers and wake up readers if data is ready. Mainly useful for tracers which
	105	* don't want to call into the wakeup code on the tracing path. Use in
	106	* combination with "read_timer_interval" channel_create() argument.
	107	*
	108	* RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
	109	* ready to read. Lower latencies before the reader is woken up. Mainly suitable
	110	* for drivers.
	111	*
	112	* RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
	113	* has the responsibility to perform wakeups.
	114	*/
	115	struct lib_ring_buffer_config {
	116	enum {
	117	RING_BUFFER_ALLOC_PER_CPU,
	118	RING_BUFFER_ALLOC_GLOBAL,
	119	} alloc;
	120	enum {
	121	RING_BUFFER_SYNC_PER_CPU, /* Wait-free */
	122	RING_BUFFER_SYNC_GLOBAL, /* Lock-free */
	123	} sync;
	124	enum {
	125	RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */
	126	RING_BUFFER_DISCARD, /* Discard when buffer full */
	127	} mode;
	128	enum {
	129	RING_BUFFER_SPLICE,
	130	RING_BUFFER_MMAP,
	131	RING_BUFFER_READ, /* TODO */
	132	RING_BUFFER_ITERATOR,
	133	RING_BUFFER_NONE,
	134	} output;
	135	enum {
	136	RING_BUFFER_PAGE,
	137	RING_BUFFER_VMAP, /* TODO */
138	RING_BUFFER_STATIC, /* TODO */
139	} backend;
140	enum {
141	RING_BUFFER_NO_OOPS_CONSISTENCY,
142	RING_BUFFER_OOPS_CONSISTENCY,
143	} oops;
144	enum {
145	RING_BUFFER_IPI_BARRIER,
146	RING_BUFFER_NO_IPI_BARRIER,
147	} ipi;
148	enum {
149	RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */
150	RING_BUFFER_WAKEUP_BY_WRITER, /*
151	* writer wakes up reader,
152	* not lock-free
153	* (takes spinlock).
154	*/
155	} wakeup;
156	/*
157	* tsc_bits: timestamp bits saved at each record.
158	* 0 and 64 disable the timestamp compression scheme.
159	*/
160	unsigned int tsc_bits;
161	struct lib_ring_buffer_client_cb cb;
162	};
163
164	/*
165	* ring buffer context
166	*
167	* Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
168	* lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
169	* lib_ring_buffer_write().
170	*/
171	struct lib_ring_buffer_ctx {
172	/* input received by lib_ring_buffer_reserve(), saved here. */
173	struct channel chan; / channel */
174	void priv; / client private data */
1d498196	175	struct shm_handle handle; / shared-memory handle */
a6352fd4 MD	176	size_t data_size; /* size of payload */
	177	int largest_align; /*
	178	* alignment of the largest element
	179	* in the payload
	180	*/
	181	int cpu; /* processor id */
	182
	183	/* output from lib_ring_buffer_reserve() */
	184	struct lib_ring_buffer buf; /
	185	* buffer corresponding to processor id
	186	* for this channel
	187	*/
	188	size_t slot_size; /* size of the reserved slot */
	189	unsigned long buf_offset; /* offset following the record header */
	190	unsigned long pre_offset; /*
	191	* Initial offset position _before_
	192	* the record is written. Positioned
	193	* prior to record header alignment
	194	* padding.
	195	*/
	196	u64 tsc; /* time-stamp counter value */
	197	unsigned int rflags; /* reservation flags */
	198	};
	199
	200	/**
	201	* lib_ring_buffer_ctx_init - initialize ring buffer context
	202	* @ctx: ring buffer context to initialize
	203	* @chan: channel
	204	* @priv: client private data
	205	* @data_size: size of record data payload
	206	* @largest_align: largest alignment within data payload types
	207	* @cpu: processor id
	208	*/
	209	static inline
	210	void lib_ring_buffer_ctx_init(struct lib_ring_buffer_ctx *ctx,
	211	struct channel chan, void priv,
	212	size_t data_size, int largest_align,
1d498196	213	int cpu, struct shm_handle *handle)
a6352fd4 MD	214	{
	215	ctx->chan = chan;
	216	ctx->priv = priv;
	217	ctx->data_size = data_size;
	218	ctx->largest_align = largest_align;
	219	ctx->cpu = cpu;
	220	ctx->rflags = 0;
1d498196	221	ctx->handle = handle;
a6352fd4 MD	222	}
	223
	224	/*
	225	* Reservation flags.
	226	*
	227	* RING_BUFFER_RFLAG_FULL_TSC
	228	*
	229	* This flag is passed to record_header_size() and to the primitive used to
	230	* write the record header. It indicates that the full 64-bit time value is
	231	* needed in the record header. If this flag is not set, the record header needs
	232	* only to contain "tsc_bits" bit of time value.
	233	*
	234	* Reservation flags can be added by the client, starting from
	235	* "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
	236	* record_header_size() to lib_ring_buffer_write_record_header().
	237	*/
	238	#define RING_BUFFER_RFLAG_FULL_TSC (1U << 0)
	239	#define RING_BUFFER_RFLAG_END (1U << 1)
	240
	241	/*
	242	* We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
	243	* compile-time. We have to duplicate the "config->align" information and the
	244	* definition here because config->align is used both in the slow and fast
	245	* paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
	246	*/
	247	#ifdef RING_BUFFER_ALIGN
	248
	249	# define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
	250
	251	/*
	252	* Calculate the offset needed to align the type.
	253	* size_of_type must be non-zero.
	254	*/
	255	static inline
	256	unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
	257	{
	258	return offset_align(align_drift, size_of_type);
	259	}
	260
	261	#else
	262
	263	# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
	264
	265	/*
	266	* Calculate the offset needed to align the type.
	267	* size_of_type must be non-zero.
	268	*/
	269	static inline
	270	unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
	271	{
	272	return 0;
	273	}
	274
	275	#endif
	276
	277	/**
	278	* lib_ring_buffer_align_ctx - Align context offset on "alignment"
	279	* @ctx: ring buffer context.
	280	*/
	281	static inline
	282	void lib_ring_buffer_align_ctx(struct lib_ring_buffer_ctx *ctx,
	283	size_t alignment)
	284	{
	285	ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
286	alignment);
287	}
288
289	/*
290	* lib_ring_buffer_check_config() returns 0 on success.
291	* Used internally to check for valid configurations at channel creation.
292	*/
293	static inline
294	int lib_ring_buffer_check_config(const struct lib_ring_buffer_config *config,
295	unsigned int switch_timer_interval,
296	unsigned int read_timer_interval)
297	{
298	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
299	&& config->sync == RING_BUFFER_SYNC_PER_CPU
300	&& switch_timer_interval)
301	return -EINVAL;
302	return 0;
303	}
304
8d8a24c8	305	#include <ust/vatomic.h>
a6352fd4 MD	306
a6352fd4 MD	307	#endif /* _LINUX_RING_BUFFER_CONFIG_H */