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
8static 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
26static 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
44static 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
76void 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}
109EXPORT_SYMBOL(rdma_dim);
110