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>
27 #include "usterr_signal_safe.h"
29 #include "backend_types.h"
33 * A switch is done during tracing or as a final flush after tracing (so it
34 * won't write in the new sub-buffer).
36 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
38 /* channel: collection of per-cpu ring buffers. */
41 unsigned long commit_count_mask
; /*
42 * Commit count mask, removing
43 * the MSBs corresponding to
44 * bits used to represent the
48 struct channel_backend backend
; /* Associated backend */
50 unsigned long switch_timer_interval
; /* Buffer flush (jiffies) */
51 unsigned long read_timer_interval
; /* Reader wakeup (jiffies) */
52 //wait_queue_head_t read_wait; /* reader wait queue */
53 int finalized
; /* Has channel been finalized */
54 struct urcu_ref ref
; /* Reference count */
55 DECLARE_SHMP(struct shm_header
, shm_header
);
56 } ____cacheline_aligned
;
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 } ____cacheline_aligned
;
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 } ____cacheline_aligned
;
69 /* ring buffer state */
70 struct 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 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)
94 union v_atomic records_lost_full
; /* Buffer full */
95 union v_atomic records_lost_wrap
; /* Nested wrap-around */
96 union v_atomic records_lost_big
; /* Events too big */
97 union v_atomic records_count
; /* Number of records written */
98 union v_atomic records_overrun
; /* Number of overwritten records */
99 //wait_queue_head_t read_wait; /* reader buffer-level wait queue */
100 int finalized
; /* buffer has been finalized */
101 //struct timer_list switch_timer; /* timer for periodical switch */
102 //struct timer_list read_timer; /* timer for read poll */
103 unsigned long get_subbuf_consumed
; /* Read-side consumed */
104 unsigned long prod_snapshot
; /* Producer count snapshot */
105 unsigned long cons_snapshot
; /* Consumer count snapshot */
106 int get_subbuf
:1; /* Sub-buffer being held by reader */
107 int switch_timer_enabled
:1; /* Protected by ring_buffer_nohz_lock */
108 int read_timer_enabled
:1; /* Protected by ring_buffer_nohz_lock */
109 } ____cacheline_aligned
;
112 void *channel_get_private(struct channel
*chan
)
114 return chan
->backend
.priv
;
118 * Issue warnings and disable channels upon internal error.
119 * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
122 #define CHAN_WARN_ON(c, cond) \
124 struct channel *__chan; \
125 int _____ret = unlikely(cond); \
127 if (__same_type(*(c), struct channel_backend)) \
128 __chan = caa_container_of((void *) (c), \
131 else if (__same_type(*(c), struct channel)) \
132 __chan = (void *) (c); \
135 uatomic_inc(&__chan->record_disabled); \
141 #endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */