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