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 if (!dim_calc_stats(&dim->start_sample, curr_sample, &curr_stats))
92 break;
93 if (rdma_dim_decision(&curr_stats, dim)) {
94 dim->state = DIM_APPLY_NEW_PROFILE;
95 schedule_work(&dim->work);
96 break;
97 }
98 fallthrough;
99 case DIM_START_MEASURE:
100 dim->state = DIM_MEASURE_IN_PROGRESS;
101 dim_update_sample_with_comps(curr_sample->event_ctr, 0, 0,
102 curr_sample->comp_ctr,
103 &dim->start_sample);
104 break;
105 case DIM_APPLY_NEW_PROFILE:
106 break;
107 }
108 }
109 EXPORT_SYMBOL(rdma_dim);
110
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