1 /* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */ 2 /* Copyright (c) 2019 Mellanox Technologies. */ 3 4 #ifndef DIM_H 5 #define DIM_H 6 7 #include <linux/bits.h> 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/types.h> 11 #include <linux/workqueue.h> 12 13 /* 14 * Number of events between DIM iterations. 15 * Causes a moderation of the algorithm run. 16 */ 17 #define DIM_NEVENTS 64 18 19 /* 20 * Is a difference between values justifies taking an action. 21 * We consider 10% difference as significant. 22 */ 23 #define IS_SIGNIFICANT_DIFF(val, ref) \ 24 ((ref) && (((100UL * abs((val) - (ref))) / (ref)) > 10)) 25 26 /* 27 * Calculate the gap between two values. 28 * Take wrap-around and variable size into consideration. 29 */ 30 #define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) \ 31 & (BIT_ULL(bits) - 1)) 32 33 /** 34 * struct dim_cq_moder - Structure for CQ moderation values. 35 * Used for communications between DIM and its consumer. 36 * 37 * @usec: CQ timer suggestion (by DIM) 38 * @pkts: CQ packet counter suggestion (by DIM) 39 * @comps: Completion counter 40 * @cq_period_mode: CQ period count mode (from CQE/EQE) 41 */ 42 struct dim_cq_moder { 43 u16 usec; 44 u16 pkts; 45 u16 comps; 46 u8 cq_period_mode; 47 }; 48 49 /** 50 * struct dim_sample - Structure for DIM sample data. 51 * Used for communications between DIM and its consumer. 52 * 53 * @time: Sample timestamp 54 * @pkt_ctr: Number of packets 55 * @byte_ctr: Number of bytes 56 * @event_ctr: Number of events 57 * @comp_ctr: Current completion counter 58 */ 59 struct dim_sample { 60 ktime_t time; 61 u32 pkt_ctr; 62 u32 byte_ctr; 63 u16 event_ctr; 64 u32 comp_ctr; 65 }; 66 67 /** 68 * struct dim_stats - Structure for DIM stats. 69 * Used for holding current measured rates. 70 * 71 * @ppms: Packets per msec 72 * @bpms: Bytes per msec 73 * @epms: Events per msec 74 * @cpms: Completions per msec 75 * @cpe_ratio: Ratio of completions to events 76 */ 77 struct dim_stats { 78 int ppms; /* packets per msec */ 79 int bpms; /* bytes per msec */ 80 int epms; /* events per msec */ 81 int cpms; /* completions per msec */ 82 int cpe_ratio; /* ratio of completions to events */ 83 }; 84 85 /** 86 * struct dim - Main structure for dynamic interrupt moderation (DIM). 87 * Used for holding all information about a specific DIM instance. 88 * 89 * @state: Algorithm state (see below) 90 * @prev_stats: Measured rates from previous iteration (for comparison) 91 * @start_sample: Sampled data at start of current iteration 92 * @measuring_sample: A &dim_sample that is used to update the current events 93 * @work: Work to perform on action required 94 * @priv: A pointer to the struct that points to dim 95 * @profile_ix: Current moderation profile 96 * @mode: CQ period count mode 97 * @tune_state: Algorithm tuning state (see below) 98 * @steps_right: Number of steps taken towards higher moderation 99 * @steps_left: Number of steps taken towards lower moderation 100 * @tired: Parking depth counter 101 */ 102 struct dim { 103 u8 state; 104 struct dim_stats prev_stats; 105 struct dim_sample start_sample; 106 struct dim_sample measuring_sample; 107 struct work_struct work; 108 void *priv; 109 u8 profile_ix; 110 u8 mode; 111 u8 tune_state; 112 u8 steps_right; 113 u8 steps_left; 114 u8 tired; 115 }; 116 117 /** 118 * enum dim_cq_period_mode - Modes for CQ period count 119 * 120 * @DIM_CQ_PERIOD_MODE_START_FROM_EQE: Start counting from EQE 121 * @DIM_CQ_PERIOD_MODE_START_FROM_CQE: Start counting from CQE (implies timer reset) 122 * @DIM_CQ_PERIOD_NUM_MODES: Number of modes 123 */ 124 enum dim_cq_period_mode { 125 DIM_CQ_PERIOD_MODE_START_FROM_EQE = 0x0, 126 DIM_CQ_PERIOD_MODE_START_FROM_CQE = 0x1, 127 DIM_CQ_PERIOD_NUM_MODES 128 }; 129 130 /** 131 * enum dim_state - DIM algorithm states 132 * 133 * These will determine if the algorithm is in a valid state to start an iteration. 134 * 135 * @DIM_START_MEASURE: This is the first iteration (also after applying a new profile) 136 * @DIM_MEASURE_IN_PROGRESS: Algorithm is already in progress - check if 137 * need to perform an action 138 * @DIM_APPLY_NEW_PROFILE: DIM consumer is currently applying a profile - no need to measure 139 */ 140 enum dim_state { 141 DIM_START_MEASURE, 142 DIM_MEASURE_IN_PROGRESS, 143 DIM_APPLY_NEW_PROFILE, 144 }; 145 146 /** 147 * enum dim_tune_state - DIM algorithm tune states 148 * 149 * These will determine which action the algorithm should perform. 150 * 151 * @DIM_PARKING_ON_TOP: Algorithm found a local top point - exit on significant difference 152 * @DIM_PARKING_TIRED: Algorithm found a deep top point - don't exit if tired > 0 153 * @DIM_GOING_RIGHT: Algorithm is currently trying higher moderation levels 154 * @DIM_GOING_LEFT: Algorithm is currently trying lower moderation levels 155 */ 156 enum dim_tune_state { 157 DIM_PARKING_ON_TOP, 158 DIM_PARKING_TIRED, 159 DIM_GOING_RIGHT, 160 DIM_GOING_LEFT, 161 }; 162 163 /** 164 * enum dim_stats_state - DIM algorithm statistics states 165 * 166 * These will determine the verdict of current iteration. 167 * 168 * @DIM_STATS_WORSE: Current iteration shows worse performance than before 169 * @DIM_STATS_SAME: Current iteration shows same performance than before 170 * @DIM_STATS_BETTER: Current iteration shows better performance than before 171 */ 172 enum dim_stats_state { 173 DIM_STATS_WORSE, 174 DIM_STATS_SAME, 175 DIM_STATS_BETTER, 176 }; 177 178 /** 179 * enum dim_step_result - DIM algorithm step results 180 * 181 * These describe the result of a step. 182 * 183 * @DIM_STEPPED: Performed a regular step 184 * @DIM_TOO_TIRED: Same kind of step was done multiple times - should go to 185 * tired parking 186 * @DIM_ON_EDGE: Stepped to the most left/right profile 187 */ 188 enum dim_step_result { 189 DIM_STEPPED, 190 DIM_TOO_TIRED, 191 DIM_ON_EDGE, 192 }; 193 194 /** 195 * dim_on_top - check if current state is a good place to stop (top location) 196 * @dim: DIM context 197 * 198 * Check if current profile is a good place to park at. 199 * This will result in reducing the DIM checks frequency as we assume we 200 * shouldn't probably change profiles, unless traffic pattern wasn't changed. 201 */ 202 bool dim_on_top(struct dim *dim); 203 204 /** 205 * dim_turn - change profile altering direction 206 * @dim: DIM context 207 * 208 * Go left if we were going right and vice-versa. 209 * Do nothing if currently parking. 210 */ 211 void dim_turn(struct dim *dim); 212 213 /** 214 * dim_park_on_top - enter a parking state on a top location 215 * @dim: DIM context 216 * 217 * Enter parking state. 218 * Clear all movement history. 219 */ 220 void dim_park_on_top(struct dim *dim); 221 222 /** 223 * dim_park_tired - enter a tired parking state 224 * @dim: DIM context 225 * 226 * Enter parking state. 227 * Clear all movement history and cause DIM checks frequency to reduce. 228 */ 229 void dim_park_tired(struct dim *dim); 230 231 /** 232 * dim_calc_stats - calculate the difference between two samples 233 * @start: start sample 234 * @end: end sample 235 * @curr_stats: delta between samples 236 * 237 * Calculate the delta between two samples (in data rates). 238 * Takes into consideration counter wrap-around. 239 * Returned boolean indicates whether curr_stats are reliable. 240 */ 241 bool dim_calc_stats(struct dim_sample *start, struct dim_sample *end, 242 struct dim_stats *curr_stats); 243 244 /** 245 * dim_update_sample - set a sample's fields with given values 246 * @event_ctr: number of events to set 247 * @packets: number of packets to set 248 * @bytes: number of bytes to set 249 * @s: DIM sample 250 */ 251 static inline void 252 dim_update_sample(u16 event_ctr, u64 packets, u64 bytes, struct dim_sample *s) 253 { 254 s->time = ktime_get(); 255 s->pkt_ctr = packets; 256 s->byte_ctr = bytes; 257 s->event_ctr = event_ctr; 258 } 259 260 /** 261 * dim_update_sample_with_comps - set a sample's fields with given 262 * values including the completion parameter 263 * @event_ctr: number of events to set 264 * @packets: number of packets to set 265 * @bytes: number of bytes to set 266 * @comps: number of completions to set 267 * @s: DIM sample 268 */ 269 static inline void 270 dim_update_sample_with_comps(u16 event_ctr, u64 packets, u64 bytes, u64 comps, 271 struct dim_sample *s) 272 { 273 dim_update_sample(event_ctr, packets, bytes, s); 274 s->comp_ctr = comps; 275 } 276 277 /* Net DIM */ 278 279 /** 280 * net_dim_get_rx_moderation - provide a CQ moderation object for the given RX profile 281 * @cq_period_mode: CQ period mode 282 * @ix: Profile index 283 */ 284 struct dim_cq_moder net_dim_get_rx_moderation(u8 cq_period_mode, int ix); 285 286 /** 287 * net_dim_get_def_rx_moderation - provide the default RX moderation 288 * @cq_period_mode: CQ period mode 289 */ 290 struct dim_cq_moder net_dim_get_def_rx_moderation(u8 cq_period_mode); 291 292 /** 293 * net_dim_get_tx_moderation - provide a CQ moderation object for the given TX profile 294 * @cq_period_mode: CQ period mode 295 * @ix: Profile index 296 */ 297 struct dim_cq_moder net_dim_get_tx_moderation(u8 cq_period_mode, int ix); 298 299 /** 300 * net_dim_get_def_tx_moderation - provide the default TX moderation 301 * @cq_period_mode: CQ period mode 302 */ 303 struct dim_cq_moder net_dim_get_def_tx_moderation(u8 cq_period_mode); 304 305 /** 306 * net_dim - main DIM algorithm entry point 307 * @dim: DIM instance information 308 * @end_sample: Current data measurement 309 * 310 * Called by the consumer. 311 * This is the main logic of the algorithm, where data is processed in order 312 * to decide on next required action. 313 */ 314 void net_dim(struct dim *dim, struct dim_sample end_sample); 315 316 /* RDMA DIM */ 317 318 /* 319 * RDMA DIM profile: 320 * profile size must be of RDMA_DIM_PARAMS_NUM_PROFILES. 321 */ 322 #define RDMA_DIM_PARAMS_NUM_PROFILES 9 323 #define RDMA_DIM_START_PROFILE 0 324 325 /** 326 * rdma_dim - Runs the adaptive moderation. 327 * @dim: The moderation struct. 328 * @completions: The number of completions collected in this round. 329 * 330 * Each call to rdma_dim takes the latest amount of completions that 331 * have been collected and counts them as a new event. 332 * Once enough events have been collected the algorithm decides a new 333 * moderation level. 334 */ 335 void rdma_dim(struct dim *dim, u64 completions); 336 337 #endif /* DIM_H */ 338