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 */
36 #include <lttng-cpuhotplug.h>
39 * A switch is done during tracing or as a final flush after tracing (so it
40 * won't write in the new sub-buffer).
42 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
44 /* channel-level read-side iterator */
46 /* Prio heap of buffers. Lowest timestamps at the top. */
47 struct lttng_ptr_heap heap
; /* Heap of struct lib_ring_buffer ptrs */
48 struct list_head empty_head
; /* Empty buffers linked-list head */
49 int read_open
; /* Opened for reading ? */
50 u64 last_qs
; /* Last quiescent state timestamp */
51 u64 last_timestamp
; /* Last timestamp (for WARN_ON) */
52 int last_cpu
; /* Last timestamp cpu */
54 * read() file operation state.
56 unsigned long len_left
;
59 /* channel: collection of per-cpu ring buffers. */
61 atomic_t record_disabled
;
62 unsigned long commit_count_mask
; /*
63 * Commit count mask, removing
64 * the MSBs corresponding to
65 * bits used to represent the
69 struct channel_backend backend
; /* Associated backend */
71 unsigned long switch_timer_interval
; /* Buffer flush (jiffies) */
72 unsigned long read_timer_interval
; /* Reader wakeup (jiffies) */
73 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
74 struct lttng_cpuhp_node cpuhp_prepare
;
75 struct lttng_cpuhp_node cpuhp_online
;
76 struct lttng_cpuhp_node cpuhp_iter_online
;
78 struct notifier_block cpu_hp_notifier
; /* CPU hotplug notifier */
79 struct notifier_block hp_iter_notifier
; /* hotplug iterator notifier */
80 unsigned int cpu_hp_enable
:1; /* Enable CPU hotplug notif. */
81 unsigned int hp_iter_enable
:1; /* Enable hp iter notif. */
83 struct notifier_block tick_nohz_notifier
; /* CPU nohz notifier */
84 wait_queue_head_t read_wait
; /* reader wait queue */
85 wait_queue_head_t hp_wait
; /* CPU hotplug wait queue */
86 int finalized
; /* Has channel been finalized */
87 struct channel_iter iter
; /* Channel read-side iterator */
88 struct kref ref
; /* Reference count */
91 /* Per-subbuffer commit counters used on the hot path */
92 struct commit_counters_hot
{
93 union v_atomic cc
; /* Commit counter */
94 union v_atomic seq
; /* Consecutive commits */
97 /* Per-subbuffer commit counters used only on cold paths */
98 struct commit_counters_cold
{
99 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
102 /* Per-buffer read iterator */
103 struct lib_ring_buffer_iter
{
104 u64 timestamp
; /* Current record timestamp */
105 size_t header_len
; /* Current record header length */
106 size_t payload_len
; /* Current record payload length */
108 struct list_head empty_node
; /* Linked list of empty buffers */
109 unsigned long consumed
, read_offset
, data_size
;
116 unsigned int allocated
:1;
117 unsigned int read_open
:1; /* Opened for reading ? */
120 /* ring buffer state */
121 struct lib_ring_buffer
{
122 /* First 32 bytes cache-hot cacheline */
123 union v_atomic offset
; /* Current offset in the buffer */
124 struct commit_counters_hot
*commit_hot
;
125 /* Commit count per sub-buffer */
126 atomic_long_t consumed
; /*
127 * Current offset in the buffer
128 * standard atomic access (shared)
130 atomic_t record_disabled
;
131 /* End of first 32 bytes cacheline */
132 union v_atomic last_tsc
; /*
133 * Last timestamp written in the buffer.
136 struct lib_ring_buffer_backend backend
; /* Associated backend */
138 struct commit_counters_cold
*commit_cold
;
139 /* Commit count per sub-buffer */
141 * timestamp_end per sub-buffer.
142 * Time is sampled by the
143 * switch_*_end() callbacks which
144 * are the last space reservation
145 * performed in the sub-buffer
146 * before it can be fully
147 * committed and delivered. This
148 * time value is then read by
149 * the deliver callback,
150 * performed by the last commit
151 * before the buffer becomes
154 atomic_long_t active_readers
; /*
155 * Active readers count
156 * standard atomic access (shared)
158 /* Dropped records */
159 union v_atomic records_lost_full
; /* Buffer full */
160 union v_atomic records_lost_wrap
; /* Nested wrap-around */
161 union v_atomic records_lost_big
; /* Events too big */
162 union v_atomic records_count
; /* Number of records written */
163 union v_atomic records_overrun
; /* Number of overwritten records */
164 wait_queue_head_t read_wait
; /* reader buffer-level wait queue */
165 wait_queue_head_t write_wait
; /* writer buffer-level wait queue (for metadata only) */
166 int finalized
; /* buffer has been finalized */
167 struct timer_list switch_timer
; /* timer for periodical switch */
168 struct timer_list read_timer
; /* timer for read poll */
169 raw_spinlock_t raw_tick_nohz_spinlock
; /* nohz entry lock/trylock */
170 struct lib_ring_buffer_iter iter
; /* read-side iterator */
171 unsigned long get_subbuf_consumed
; /* Read-side consumed */
172 unsigned long prod_snapshot
; /* Producer count snapshot */
173 unsigned long cons_snapshot
; /* Consumer count snapshot */
174 unsigned int get_subbuf
:1, /* Sub-buffer being held by reader */
175 switch_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
176 read_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
181 void *channel_get_private(struct channel
*chan
)
183 return chan
->backend
.priv
;
186 void lib_ring_buffer_lost_event_too_big(struct channel
*chan
);
189 * Issue warnings and disable channels upon internal error.
190 * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
193 #define CHAN_WARN_ON(c, cond) \
195 struct channel *__chan; \
196 int _____ret = unlikely(cond); \
198 if (__same_type(*(c), struct channel_backend)) \
199 __chan = container_of((void *) (c), \
202 else if (__same_type(*(c), struct channel)) \
203 __chan = (void *) (c); \
206 atomic_inc(&__chan->record_disabled); \
212 #endif /* _LIB_RING_BUFFER_FRONTEND_TYPES_H */