1 #ifndef _LIB_RING_BUFFER_FRONTEND_TYPES_H
2 #define _LIB_RING_BUFFER_FRONTEND_TYPES_H
5 * lib/ringbuffer/frontend_types.h
7 * Ring Buffer Library Synchronization Header (types).
9 * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; only
14 * version 2.1 of the License.
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
28 * See ring_buffer_frontend.c for more information on wait-free algorithms.
31 #include <linux/kref.h>
32 #include "../../wrapper/ringbuffer/config.h"
33 #include "../../wrapper/ringbuffer/backend_types.h"
34 #include "../../wrapper/spinlock.h"
35 #include "../../lib/prio_heap/lttng_prio_heap.h" /* For per-CPU read-side iterator */
38 * A switch is done during tracing or as a final flush after tracing (so it
39 * won't write in the new sub-buffer).
41 enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
43 /* channel-level read-side iterator */
45 /* Prio heap of buffers. Lowest timestamps at the top. */
46 struct lttng_ptr_heap heap; /* Heap of struct lib_ring_buffer ptrs */
47 struct list_head empty_head; /* Empty buffers linked-list head */
48 int read_open; /* Opened for reading ? */
49 u64 last_qs; /* Last quiescent state timestamp */
50 u64 last_timestamp; /* Last timestamp (for WARN_ON) */
51 int last_cpu; /* Last timestamp cpu */
53 * read() file operation state.
55 unsigned long len_left;
58 /* channel: collection of per-cpu ring buffers. */
60 atomic_t record_disabled;
61 unsigned long commit_count_mask; /*
62 * Commit count mask, removing
63 * the MSBs corresponding to
64 * bits used to represent the
68 struct channel_backend backend; /* Associated backend */
70 unsigned long switch_timer_interval; /* Buffer flush (jiffies) */
71 unsigned long read_timer_interval; /* Reader wakeup (jiffies) */
72 struct notifier_block cpu_hp_notifier; /* CPU hotplug notifier */
73 struct notifier_block tick_nohz_notifier; /* CPU nohz notifier */
74 struct notifier_block hp_iter_notifier; /* hotplug iterator notifier */
75 unsigned int cpu_hp_enable:1; /* Enable CPU hotplug notif. */
76 unsigned int hp_iter_enable:1; /* Enable hp iter notif. */
77 wait_queue_head_t read_wait; /* reader wait queue */
78 wait_queue_head_t hp_wait; /* CPU hotplug wait queue */
79 int finalized; /* Has channel been finalized */
80 struct channel_iter iter; /* Channel read-side iterator */
81 struct kref ref; /* Reference count */
84 /* Per-subbuffer commit counters used on the hot path */
85 struct commit_counters_hot {
86 union v_atomic cc; /* Commit counter */
87 union v_atomic seq; /* Consecutive commits */
90 /* Per-subbuffer commit counters used only on cold paths */
91 struct commit_counters_cold {
92 union v_atomic cc_sb; /* Incremented _once_ at sb switch */
95 /* Per-buffer read iterator */
96 struct lib_ring_buffer_iter {
97 u64 timestamp; /* Current record timestamp */
98 size_t header_len; /* Current record header length */
99 size_t payload_len; /* Current record payload length */
101 struct list_head empty_node; /* Linked list of empty buffers */
102 unsigned long consumed, read_offset, data_size;
109 unsigned int allocated:1;
110 unsigned int read_open:1; /* Opened for reading ? */
113 /* ring buffer state */
114 struct lib_ring_buffer {
115 /* First 32 bytes cache-hot cacheline */
116 union v_atomic offset; /* Current offset in the buffer */
117 struct commit_counters_hot *commit_hot;
118 /* Commit count per sub-buffer */
119 atomic_long_t consumed; /*
120 * Current offset in the buffer
121 * standard atomic access (shared)
123 atomic_t record_disabled;
124 /* End of first 32 bytes cacheline */
125 union v_atomic last_tsc; /*
126 * Last timestamp written in the buffer.
129 struct lib_ring_buffer_backend backend; /* Associated backend */
131 struct commit_counters_cold *commit_cold;
132 /* Commit count per sub-buffer */
133 atomic_long_t active_readers; /*
134 * Active readers count
135 * standard atomic access (shared)
137 /* Dropped records */
138 union v_atomic records_lost_full; /* Buffer full */
139 union v_atomic records_lost_wrap; /* Nested wrap-around */
140 union v_atomic records_lost_big; /* Events too big */
141 union v_atomic records_count; /* Number of records written */
142 union v_atomic records_overrun; /* Number of overwritten records */
143 wait_queue_head_t read_wait; /* reader buffer-level wait queue */
144 wait_queue_head_t write_wait; /* writer buffer-level wait queue (for metadata only) */
145 int finalized; /* buffer has been finalized */
146 struct timer_list switch_timer; /* timer for periodical switch */
147 struct timer_list read_timer; /* timer for read poll */
148 raw_spinlock_t raw_tick_nohz_spinlock; /* nohz entry lock/trylock */
149 struct lib_ring_buffer_iter iter; /* read-side iterator */
150 unsigned long get_subbuf_consumed; /* Read-side consumed */
151 unsigned long prod_snapshot; /* Producer count snapshot */
152 unsigned long cons_snapshot; /* Consumer count snapshot */
153 unsigned int get_subbuf:1, /* Sub-buffer being held by reader */
154 switch_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */
155 read_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */
159 void *channel_get_private(struct channel *chan)
161 return chan->backend.priv;
165 * Issue warnings and disable channels upon internal error.
166 * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
169 #define CHAN_WARN_ON(c, cond) \
171 struct channel *__chan; \
172 int _____ret = unlikely(cond); \
174 if (__same_type(*(c), struct channel_backend)) \
175 __chan = container_of((void *) (c), \
178 else if (__same_type(*(c), struct channel)) \
179 __chan = (void *) (c); \
182 atomic_inc(&__chan->record_disabled); \
188 #endif /* _LIB_RING_BUFFER_FRONTEND_TYPES_H */