lib/dim/rdma_dim.c

   1 // SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
   2 /*
   3  * Copyright (c) 2019, Mellanox Technologies inc.  All rights reserved.
   4  */
   5
   6 #include <linux/dim.h>
   7
   8 static int rdma_dim_step(struct dim *dim)
   9 {
  10         if (dim->tune_state == DIM_GOING_RIGHT) {
  11                 if (dim->profile_ix == (RDMA_DIM_PARAMS_NUM_PROFILES - 1))
  12                         return DIM_ON_EDGE;
  13                 dim->profile_ix++;
  14                 dim->steps_right++;
  15         }
  16         if (dim->tune_state == DIM_GOING_LEFT) {
  17                 if (dim->profile_ix == 0)
  18                         return DIM_ON_EDGE;
  19                 dim->profile_ix--;
  20                 dim->steps_left++;
  21         }
  22
  23         return DIM_STEPPED;
  24 }
  25
  26 static int rdma_dim_stats_compare(struct dim_stats *curr,
  27                                   struct dim_stats *prev)
  28 {
  29         /* first stat */
  30         if (!prev->cpms)
  31                 return DIM_STATS_SAME;
  32
  33         if (IS_SIGNIFICANT_DIFF(curr->cpms, prev->cpms))
  34                 return (curr->cpms > prev->cpms) ? DIM_STATS_BETTER :
  35                                                 DIM_STATS_WORSE;
  36
  37         if (IS_SIGNIFICANT_DIFF(curr->cpe_ratio, prev->cpe_ratio))
  38                 return (curr->cpe_ratio > prev->cpe_ratio) ? DIM_STATS_BETTER :
  39                                                 DIM_STATS_WORSE;
  40
  41         return DIM_STATS_SAME;
  42 }
  43
  44 static bool rdma_dim_decision(struct dim_stats *curr_stats, struct dim *dim)
  45 {
  46         int prev_ix = dim->profile_ix;
  47         u8 state = dim->tune_state;
  48         int stats_res;
  49         int step_res;
  50
  51         if (state != DIM_PARKING_ON_TOP && state != DIM_PARKING_TIRED) {
  52                 stats_res = rdma_dim_stats_compare(curr_stats,
  53                                                    &dim->prev_stats);
  54
  55                 switch (stats_res) {
  56                 case DIM_STATS_SAME:
  57                         if (curr_stats->cpe_ratio <= 50 * prev_ix)
  58                                 dim->profile_ix = 0;
  59                         break;
  60                 case DIM_STATS_WORSE:
  61                         dim_turn(dim);
  62                         fallthrough;
  63                 case DIM_STATS_BETTER:
  64                         step_res = rdma_dim_step(dim);
  65                         if (step_res == DIM_ON_EDGE)
  66                                 dim_turn(dim);
  67                         break;
  68                 }
  69         }
  70
  71         dim->prev_stats = *curr_stats;
  72
  73         return dim->profile_ix != prev_ix;
  74 }
  75
  76 void rdma_dim(struct dim *dim, u64 completions)
  77 {
  78         struct dim_sample *curr_sample = &dim->measuring_sample;
  79         struct dim_stats curr_stats;
  80         u32 nevents;
  81
  82         dim_update_sample_with_comps(curr_sample->event_ctr + 1, 0, 0,
  83                                      curr_sample->comp_ctr + completions,
  84                                      &dim->measuring_sample);
  85
  86         switch (dim->state) {
  87         case DIM_MEASURE_IN_PROGRESS:
  88                 nevents = curr_sample->event_ctr - dim->start_sample.event_ctr;
  89                 if (nevents < DIM_NEVENTS)
  90                         break;
  91                 dim_calc_stats(&dim->start_sample, curr_sample, &curr_stats);
  92                 if (rdma_dim_decision(&curr_stats, dim)) {
  93                         dim->state = DIM_APPLY_NEW_PROFILE;
  94                         schedule_work(&dim->work);
  95                         break;
  96                 }
  97                 fallthrough;
  98         case DIM_START_MEASURE:
  99                 dim->state = DIM_MEASURE_IN_PROGRESS;
 100                 dim_update_sample_with_comps(curr_sample->event_ctr, 0, 0,
 101                                              curr_sample->comp_ctr,
 102                                              &dim->start_sample);
 103                 break;
 104         case DIM_APPLY_NEW_PROFILE:
 105                 break;
 106         }
 107 }
 108 EXPORT_SYMBOL(rdma_dim);