Quellcode-Bibliothek rdma_dim.c

// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/*
 * Copyright (c) 2019, Mellanox Technologies inc.  All rights reserved.
 */

#include <linux/dim.h>

static int rdma_dim_step(struct dim *dim)
{
 if (dim->tune_state == DIM_GOING_RIGHT) {
  if (dim->profile_ix == (RDMA_DIM_PARAMS_NUM_PROFILES - 1))
   return DIM_ON_EDGE;
  dim->profile_ix++;
  dim->steps_right++;
 }
 if (dim->tune_state == DIM_GOING_LEFT) {
  if (dim->profile_ix == 0)
   return DIM_ON_EDGE;
  dim->profile_ix--;
  dim->steps_left++;
 }

 return DIM_STEPPED;
}

static int rdma_dim_stats_compare(struct dim_stats *curr,
      struct dim_stats *prev)
{
 /* first stat */
 if (!prev->cpms)
  return DIM_STATS_SAME;

 if (IS_SIGNIFICANT_DIFF(curr->cpms, prev->cpms))
  return (curr->cpms > prev->cpms) ? DIM_STATS_BETTER :
      DIM_STATS_WORSE;

 if (IS_SIGNIFICANT_DIFF(curr->cpe_ratio, prev->cpe_ratio))
  return (curr->cpe_ratio > prev->cpe_ratio) ? DIM_STATS_BETTER :
      DIM_STATS_WORSE;

 return DIM_STATS_SAME;
}

static bool rdma_dim_decision(struct dim_stats *curr_stats, struct dim *dim)
{
 int prev_ix = dim->profile_ix;
 u8 state = dim->tune_state;
 int stats_res;
 int step_res;

 if (state != DIM_PARKING_ON_TOP && state != DIM_PARKING_TIRED) {
  stats_res = rdma_dim_stats_compare(curr_stats,
         &dim->prev_stats);

  switch (stats_res) {
  case DIM_STATS_SAME:
   if (curr_stats->cpe_ratio <= 50 * prev_ix)
    dim->profile_ix = 0;
   break;
  case DIM_STATS_WORSE:
   dim_turn(dim);
   fallthrough;
  case DIM_STATS_BETTER:
   step_res = rdma_dim_step(dim);
   if (step_res == DIM_ON_EDGE)
    dim_turn(dim);
   break;
  }
 }

 dim->prev_stats = *curr_stats;

 return dim->profile_ix != prev_ix;
}

void rdma_dim(struct dim *dim, u64 completions)
{
 struct dim_sample *curr_sample = &dim->measuring_sample;
 struct dim_stats curr_stats;
 u32 nevents;

 dim_update_sample_with_comps(curr_sample->event_ctr + 1, 0, 0,
         curr_sample->comp_ctr + completions,
         &dim->measuring_sample);

 switch (dim->state) {
 case DIM_MEASURE_IN_PROGRESS:
  nevents = curr_sample->event_ctr - dim->start_sample.event_ctr;
  if (nevents < DIM_NEVENTS)
   break;
  if (!dim_calc_stats(&dim->start_sample, curr_sample, &curr_stats))
   break;
  if (rdma_dim_decision(&curr_stats, dim)) {
   dim->state = DIM_APPLY_NEW_PROFILE;
   schedule_work(&dim->work);
   break;
  }
  fallthrough;
 case DIM_START_MEASURE:
  dim->state = DIM_MEASURE_IN_PROGRESS;
  dim_update_sample_with_comps(curr_sample->event_ctr, 0, 0,
          curr_sample->comp_ctr,
          &dim->start_sample);
  break;
 case DIM_APPLY_NEW_PROFILE:
  break;
 }
}
EXPORT_SYMBOL(rdma_dim);