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. */
37 #define RB_CHANNEL_PADDING 64
40 unsigned long commit_count_mask
; /*
41 * Commit count mask, removing
42 * the MSBs corresponding to
43 * bits used to represent the
47 unsigned long switch_timer_interval
; /* Buffer flush (jiffies) */
48 unsigned long read_timer_interval
; /* Reader wakeup (jiffies) */
49 //wait_queue_head_t read_wait; /* reader wait queue */
50 int finalized
; /* Has channel been finalized */
51 size_t priv_data_offset
;
53 * Associated backend contains a variable-length array. Needs to
56 struct channel_backend backend
; /* Associated backend */
57 char padding
[RB_CHANNEL_PADDING
];
58 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
60 /* Per-subbuffer commit counters used on the hot path */
61 #define RB_COMMIT_COUNT_HOT_PADDING 16
62 struct commit_counters_hot
{
63 union v_atomic cc
; /* Commit counter */
64 union v_atomic seq
; /* Consecutive commits */
65 char padding
[RB_COMMIT_COUNT_HOT_PADDING
];
66 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
68 /* Per-subbuffer commit counters used only on cold paths */
69 #define RB_COMMIT_COUNT_COLD_PADDING 24
70 struct commit_counters_cold
{
71 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
72 char padding
[RB_COMMIT_COUNT_COLD_PADDING
];
73 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
75 /* ring buffer state */
76 #define RB_RING_BUFFER_PADDING 64
77 struct lttng_ust_lib_ring_buffer
{
78 /* First 32 bytes cache-hot cacheline */
79 union v_atomic offset
; /* Current offset in the buffer */
80 DECLARE_SHMP(struct commit_counters_hot
, commit_hot
);
81 /* Commit count per sub-buffer */
83 * Current offset in the buffer
84 * standard atomic access (shared)
87 /* End of first 32 bytes cacheline */
88 union v_atomic last_tsc
; /*
89 * Last timestamp written in the buffer.
92 struct lttng_ust_lib_ring_buffer_backend backend
; /* Associated backend */
94 DECLARE_SHMP(struct commit_counters_cold
, commit_cold
);
95 /* Commit count per sub-buffer */
96 long active_readers
; /*
97 * Active readers count
98 * standard atomic access (shared)
100 long active_shadow_readers
;
101 /* Dropped records */
102 union v_atomic records_lost_full
; /* Buffer full */
103 union v_atomic records_lost_wrap
; /* Nested wrap-around */
104 union v_atomic records_lost_big
; /* Events too big */
105 union v_atomic records_count
; /* Number of records written */
106 union v_atomic records_overrun
; /* Number of overwritten records */
107 //wait_queue_head_t read_wait; /* reader buffer-level wait queue */
108 int finalized
; /* buffer has been finalized */
109 //struct timer_list switch_timer; /* timer for periodical switch */
110 //struct timer_list read_timer; /* timer for read poll */
111 unsigned long get_subbuf_consumed
; /* Read-side consumed */
112 unsigned long prod_snapshot
; /* Producer count snapshot */
113 unsigned long cons_snapshot
; /* Consumer count snapshot */
114 unsigned int get_subbuf
:1, /* Sub-buffer being held by reader */
115 switch_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
116 read_timer_enabled
:1; /* Protected by ring_buffer_nohz_lock */
117 /* shmp pointer to self */
118 DECLARE_SHMP(struct lttng_ust_lib_ring_buffer
, self
);
119 char padding
[RB_RING_BUFFER_PADDING
];
120 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
123 void *channel_get_private(struct channel
*chan
)
125 return ((char *) chan
) + chan
->priv_data_offset
;
128 #ifndef __rb_same_type
129 #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
133 * Issue warnings and disable channels upon internal error.
134 * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
137 #define CHAN_WARN_ON(c, cond) \
139 struct channel *__chan; \
140 int _____ret = caa_unlikely(cond); \
142 if (__rb_same_type(*(c), struct channel_backend)) \
143 __chan = caa_container_of((void *) (c), \
146 else if (__rb_same_type(*(c), struct channel)) \
147 __chan = (void *) (c); \
150 uatomic_inc(&__chan->record_disabled); \
156 #endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */