include/linux/dim.h

   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         (((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  */
 240 void dim_calc_stats(struct dim_sample *start, struct dim_sample *end,
 241                     struct dim_stats *curr_stats);
 242
 243 /**
 244  *      dim_update_sample - set a sample's fields with given values
 245  *      @event_ctr: number of events to set
 246  *      @packets: number of packets to set
 247  *      @bytes: number of bytes to set
 248  *      @s: DIM sample
 249  */
 250 static inline void
 251 dim_update_sample(u16 event_ctr, u64 packets, u64 bytes, struct dim_sample *s)
 252 {
 253         s->time      = ktime_get();
 254         s->pkt_ctr   = packets;
 255         s->byte_ctr  = bytes;
 256         s->event_ctr = event_ctr;
 257 }
 258
 259 /**
 260  *      dim_update_sample_with_comps - set a sample's fields with given
 261  *      values including the completion parameter
 262  *      @event_ctr: number of events to set
 263  *      @packets: number of packets to set
 264  *      @bytes: number of bytes to set
 265  *      @comps: number of completions to set
 266  *      @s: DIM sample
 267  */
 268 static inline void
 269 dim_update_sample_with_comps(u16 event_ctr, u64 packets, u64 bytes, u64 comps,
 270                              struct dim_sample *s)
 271 {
 272         dim_update_sample(event_ctr, packets, bytes, s);
 273         s->comp_ctr = comps;
 274 }
 275
 276 /* Net DIM */
 277
 278 /**
 279  *      net_dim_get_rx_moderation - provide a CQ moderation object for the given RX profile
 280  *      @cq_period_mode: CQ period mode
 281  *      @ix: Profile index
 282  */
 283 struct dim_cq_moder net_dim_get_rx_moderation(u8 cq_period_mode, int ix);
 284
 285 /**
 286  *      net_dim_get_def_rx_moderation - provide the default RX moderation
 287  *      @cq_period_mode: CQ period mode
 288  */
 289 struct dim_cq_moder net_dim_get_def_rx_moderation(u8 cq_period_mode);
 290
 291 /**
 292  *      net_dim_get_tx_moderation - provide a CQ moderation object for the given TX profile
 293  *      @cq_period_mode: CQ period mode
 294  *      @ix: Profile index
 295  */
 296 struct dim_cq_moder net_dim_get_tx_moderation(u8 cq_period_mode, int ix);
 297
 298 /**
 299  *      net_dim_get_def_tx_moderation - provide the default TX moderation
 300  *      @cq_period_mode: CQ period mode
 301  */
 302 struct dim_cq_moder net_dim_get_def_tx_moderation(u8 cq_period_mode);
 303
 304 /**
 305  *      net_dim - main DIM algorithm entry point
 306  *      @dim: DIM instance information
 307  *      @end_sample: Current data measurement
 308  *
 309  * Called by the consumer.
 310  * This is the main logic of the algorithm, where data is processed in order
 311  * to decide on next required action.
 312  */
 313 void net_dim(struct dim *dim, struct dim_sample end_sample);
 314
 315 /* RDMA DIM */
 316
 317 /*
 318  * RDMA DIM profile:
 319  * profile size must be of RDMA_DIM_PARAMS_NUM_PROFILES.
 320  */
 321 #define RDMA_DIM_PARAMS_NUM_PROFILES 9
 322 #define RDMA_DIM_START_PROFILE 0
 323
 324 /**
 325  * rdma_dim - Runs the adaptive moderation.
 326  * @dim: The moderation struct.
 327  * @completions: The number of completions collected in this round.
 328  *
 329  * Each call to rdma_dim takes the latest amount of completions that
 330  * have been collected and counts them as a new event.
 331  * Once enough events have been collected the algorithm decides a new
 332  * moderation level.
 333  */
 334 void rdma_dim(struct dim *dim, u64 completions);
 335
 336 #endif /* DIM_H */