1 #ifndef _LINUX_RING_BUFFER_FRONTEND_TYPES_H
2 #define _LINUX_RING_BUFFER_FRONTEND_TYPES_H
5 * linux/ringbuffer/frontend_types.h
7 * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 * Ring Buffer Library Synchronization Header (types).
12 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
14 * See ring_buffer_frontend.c for more information on wait-free algorithms.
16 * Dual LGPL v2.1/GPL v2 license.
21 #include <urcu/list.h>
22 #include <urcu/uatomic.h>
24 #include <lttng/ringbuffer-config.h>
25 #include <usterr-signal-safe.h>
26 #include "backend_types.h"
27 #include "shm_internal.h"
31 * A switch is done during tracing or as a final flush after tracing (so it
32 * won't write in the new sub-buffer).
34 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
36 /* channel: collection of per-cpu ring buffers. */
39 unsigned long commit_count_mask
; /*
40 * Commit count mask, removing
41 * the MSBs corresponding to
42 * bits used to represent the
46 unsigned long switch_timer_interval
; /* Buffer flush (jiffies) */
47 unsigned long read_timer_interval
; /* Reader wakeup (jiffies) */
48 //wait_queue_head_t read_wait; /* reader wait queue */
49 int finalized
; /* Has channel been finalized */
50 size_t priv_data_offset
;
52 * Associated backend contains a variable-length array. Needs to
55 struct channel_backend backend
; /* Associated backend */
56 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
58 /* Per-subbuffer commit counters used on the hot path */
59 struct commit_counters_hot
{
60 union v_atomic cc
; /* Commit counter */
61 union v_atomic seq
; /* Consecutive commits */
62 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
64 /* Per-subbuffer commit counters used only on cold paths */
65 struct commit_counters_cold
{
66 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
67 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
69 /* ring buffer state */
70 struct lttng_ust_lib_ring_buffer
{
71 /* First 32 bytes cache-hot cacheline */
72 union v_atomic offset
; /* Current offset in the buffer */
73 DECLARE_SHMP(struct commit_counters_hot
, commit_hot
);
74 /* Commit count per sub-buffer */
76 * Current offset in the buffer
77 * standard atomic access (shared)
80 /* End of first 32 bytes cacheline */
81 union v_atomic last_tsc
; /*
82 * Last timestamp written in the buffer.
85 struct lttng_ust_lib_ring_buffer_backend backend
; /* Associated backend */
87 DECLARE_SHMP(struct commit_counters_cold
, commit_cold
);
88 /* Commit count per sub-buffer */
89 long active_readers
; /*
90 * Active readers count
91 * standard atomic access (shared)
93 long active_shadow_readers
;
95 union v_atomic records_lost_full
; /* Buffer full */
96 union v_atomic records_lost_wrap
; /* Nested wrap-around */
97 union v_atomic records_lost_big
; /* Events too big */
98 union v_atomic records_count
; /* Number of records written */
99 union v_atomic records_overrun
; /* Number of overwritten records */
100 //wait_queue_head_t read_wait; /* reader buffer-level wait queue */
101 int finalized
; /* buffer has been finalized */
102 //struct timer_list switch_timer; /* timer for periodical switch */
103 //struct timer_list read_timer; /* timer for read poll */
104 unsigned long get_subbuf_consumed
; /* Read-side consumed */
105 unsigned long prod_snapshot
; /* Producer count snapshot */
106 unsigned long cons_snapshot
; /* Consumer count snapshot */
107 unsigned int get_subbuf
:1, /* Sub-buffer being held by reader */
108 switch_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
109 read_timer_enabled
:1; /* Protected by ring_buffer_nohz_lock */
110 /* shmp pointer to self */
111 DECLARE_SHMP(struct lttng_ust_lib_ring_buffer
, self
);
112 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
115 void *channel_get_private(struct channel
*chan
)
117 return ((char *) chan
) + chan
->priv_data_offset
;
120 #ifndef __rb_same_type
121 #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
125 * Issue warnings and disable channels upon internal error.
126 * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
129 #define CHAN_WARN_ON(c, cond) \
131 struct channel *__chan; \
132 int _____ret = caa_unlikely(cond); \
134 if (__rb_same_type(*(c), struct channel_backend)) \
135 __chan = caa_container_of((void *) (c), \
138 else if (__rb_same_type(*(c), struct channel)) \
139 __chan = (void *) (c); \
142 uatomic_inc(&__chan->record_disabled); \
148 #endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */