GNU Linux-libre 5.19-rc6-gnu
[releases.git] / 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);