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: curr_stats, |
53 | prev: &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(event_ctr: curr_sample->event_ctr + 1, packets: 0, bytes: 0, |
83 | comps: curr_sample->comp_ctr + completions, |
84 | s: &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(start: &dim->start_sample, end: curr_sample, curr_stats: &curr_stats)) |
92 | break; |
93 | if (rdma_dim_decision(curr_stats: &curr_stats, dim)) { |
94 | dim->state = DIM_APPLY_NEW_PROFILE; |
95 | schedule_work(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(event_ctr: curr_sample->event_ctr, packets: 0, bytes: 0, |
102 | comps: curr_sample->comp_ctr, |
103 | s: &dim->start_sample); |
104 | break; |
105 | case DIM_APPLY_NEW_PROFILE: |
106 | break; |
107 | } |
108 | } |
109 | EXPORT_SYMBOL(rdma_dim); |
110 | |