| 1 | #ifndef _LTTNG_RING_BUFFER_FRONTEND_TYPES_H |
| 2 | #define _LTTNG_RING_BUFFER_FRONTEND_TYPES_H |
| 3 | |
| 4 | /* |
| 5 | * libringbuffer/frontend_types.h |
| 6 | * |
| 7 | * Ring Buffer Library Synchronization Header (types). |
| 8 | * |
| 9 | * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 10 | * |
| 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. |
| 15 | * |
| 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. |
| 20 | * |
| 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 |
| 24 | * |
| 25 | * Author: |
| 26 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 27 | * |
| 28 | * See ring_buffer_frontend.c for more information on wait-free algorithms. |
| 29 | */ |
| 30 | |
| 31 | #include <string.h> |
| 32 | |
| 33 | #include <urcu/list.h> |
| 34 | #include <urcu/uatomic.h> |
| 35 | |
| 36 | #include <lttng/ringbuffer-config.h> |
| 37 | #include <usterr-signal-safe.h> |
| 38 | #include "backend_types.h" |
| 39 | #include "shm_internal.h" |
| 40 | #include "vatomic.h" |
| 41 | |
| 42 | /* |
| 43 | * A switch is done during tracing or as a final flush after tracing (so it |
| 44 | * won't write in the new sub-buffer). |
| 45 | */ |
| 46 | enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH }; |
| 47 | |
| 48 | /* channel: collection of per-cpu ring buffers. */ |
| 49 | struct channel { |
| 50 | int record_disabled; |
| 51 | unsigned long commit_count_mask; /* |
| 52 | * Commit count mask, removing |
| 53 | * the MSBs corresponding to |
| 54 | * bits used to represent the |
| 55 | * subbuffer index. |
| 56 | */ |
| 57 | |
| 58 | unsigned long switch_timer_interval; /* Buffer flush (jiffies) */ |
| 59 | unsigned long read_timer_interval; /* Reader wakeup (jiffies) */ |
| 60 | //wait_queue_head_t read_wait; /* reader wait queue */ |
| 61 | int finalized; /* Has channel been finalized */ |
| 62 | size_t priv_data_offset; |
| 63 | /* Note: padding field is missing */ |
| 64 | /* |
| 65 | * Associated backend contains a variable-length array. Needs to |
| 66 | * be last member. |
| 67 | */ |
| 68 | struct channel_backend backend; /* Associated backend */ |
| 69 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 70 | |
| 71 | /* Per-subbuffer commit counters used on the hot path */ |
| 72 | #define RB_COMMIT_COUNT_HOT_PADDING 16 |
| 73 | struct commit_counters_hot { |
| 74 | union v_atomic cc; /* Commit counter */ |
| 75 | union v_atomic seq; /* Consecutive commits */ |
| 76 | char padding[RB_COMMIT_COUNT_HOT_PADDING]; |
| 77 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 78 | |
| 79 | /* Per-subbuffer commit counters used only on cold paths */ |
| 80 | #define RB_COMMIT_COUNT_COLD_PADDING 24 |
| 81 | struct commit_counters_cold { |
| 82 | union v_atomic cc_sb; /* Incremented _once_ at sb switch */ |
| 83 | char padding[RB_COMMIT_COUNT_COLD_PADDING]; |
| 84 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 85 | |
| 86 | /* ring buffer state */ |
| 87 | #define RB_RING_BUFFER_PADDING 64 |
| 88 | struct lttng_ust_lib_ring_buffer { |
| 89 | /* First 32 bytes cache-hot cacheline */ |
| 90 | union v_atomic offset; /* Current offset in the buffer */ |
| 91 | DECLARE_SHMP(struct commit_counters_hot, commit_hot); |
| 92 | /* Commit count per sub-buffer */ |
| 93 | long consumed; /* |
| 94 | * Current offset in the buffer |
| 95 | * standard atomic access (shared) |
| 96 | */ |
| 97 | int record_disabled; |
| 98 | /* End of first 32 bytes cacheline */ |
| 99 | union v_atomic last_tsc; /* |
| 100 | * Last timestamp written in the buffer. |
| 101 | */ |
| 102 | |
| 103 | struct lttng_ust_lib_ring_buffer_backend backend; /* Associated backend */ |
| 104 | |
| 105 | DECLARE_SHMP(struct commit_counters_cold, commit_cold); |
| 106 | /* Commit count per sub-buffer */ |
| 107 | long active_readers; /* |
| 108 | * Active readers count |
| 109 | * standard atomic access (shared) |
| 110 | */ |
| 111 | long active_shadow_readers; |
| 112 | /* Dropped records */ |
| 113 | union v_atomic records_lost_full; /* Buffer full */ |
| 114 | union v_atomic records_lost_wrap; /* Nested wrap-around */ |
| 115 | union v_atomic records_lost_big; /* Events too big */ |
| 116 | union v_atomic records_count; /* Number of records written */ |
| 117 | union v_atomic records_overrun; /* Number of overwritten records */ |
| 118 | //wait_queue_head_t read_wait; /* reader buffer-level wait queue */ |
| 119 | int finalized; /* buffer has been finalized */ |
| 120 | //struct timer_list switch_timer; /* timer for periodical switch */ |
| 121 | //struct timer_list read_timer; /* timer for read poll */ |
| 122 | unsigned long get_subbuf_consumed; /* Read-side consumed */ |
| 123 | unsigned long prod_snapshot; /* Producer count snapshot */ |
| 124 | unsigned long cons_snapshot; /* Consumer count snapshot */ |
| 125 | unsigned int get_subbuf:1, /* Sub-buffer being held by reader */ |
| 126 | switch_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */ |
| 127 | read_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */ |
| 128 | /* shmp pointer to self */ |
| 129 | DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, self); |
| 130 | char padding[RB_RING_BUFFER_PADDING]; |
| 131 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 132 | |
| 133 | static inline |
| 134 | void *channel_get_private(struct channel *chan) |
| 135 | { |
| 136 | return ((char *) chan) + chan->priv_data_offset; |
| 137 | } |
| 138 | |
| 139 | #ifndef __rb_same_type |
| 140 | #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) |
| 141 | #endif |
| 142 | |
| 143 | /* |
| 144 | * Issue warnings and disable channels upon internal error. |
| 145 | * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend |
| 146 | * parameters. |
| 147 | */ |
| 148 | #define CHAN_WARN_ON(c, cond) \ |
| 149 | ({ \ |
| 150 | struct channel *__chan; \ |
| 151 | int _____ret = caa_unlikely(cond); \ |
| 152 | if (_____ret) { \ |
| 153 | if (__rb_same_type(*(c), struct channel_backend)) \ |
| 154 | __chan = caa_container_of((void *) (c), \ |
| 155 | struct channel, \ |
| 156 | backend); \ |
| 157 | else if (__rb_same_type(*(c), struct channel)) \ |
| 158 | __chan = (void *) (c); \ |
| 159 | else \ |
| 160 | BUG_ON(1); \ |
| 161 | uatomic_inc(&__chan->record_disabled); \ |
| 162 | WARN_ON(1); \ |
| 163 | } \ |
| 164 | _____ret; \ |
| 165 | }) |
| 166 | |
| 167 | #endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */ |