1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Memory Bandwidth Monitoring (MBM) test
4 *
5 * Copyright (C) 2018 Intel Corporation
6 *
7 * Authors:
8 * Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
9 * Fenghua Yu <fenghua.yu@intel.com>
10 */
11#include "resctrl.h"
12
13#define RESULT_FILE_NAME "result_mbm"
14#define MAX_DIFF_PERCENT 8
15#define NUM_OF_RUNS 5
16
17static int
18show_bw_info(unsigned long *bw_imc, unsigned long *bw_resc, size_t span)
19{
20 unsigned long avg_bw_imc = 0, avg_bw_resc = 0;
21 unsigned long sum_bw_imc = 0, sum_bw_resc = 0;
22 int runs, ret, avg_diff_per;
23 float avg_diff = 0;
24
25 /*
26 * Discard the first value which is inaccurate due to monitoring setup
27 * transition phase.
28 */
29 for (runs = 1; runs < NUM_OF_RUNS ; runs++) {
30 sum_bw_imc += bw_imc[runs];
31 sum_bw_resc += bw_resc[runs];
32 }
33
34 avg_bw_imc = sum_bw_imc / 4;
35 avg_bw_resc = sum_bw_resc / 4;
36 avg_diff = (float)labs(avg_bw_resc - avg_bw_imc) / avg_bw_imc;
37 avg_diff_per = (int)(avg_diff * 100);
38
39 ret = avg_diff_per > MAX_DIFF_PERCENT;
40 ksft_print_msg(msg: "%s Check MBM diff within %d%%\n",
41 ret ? "Fail:" : "Pass:", MAX_DIFF_PERCENT);
42 ksft_print_msg(msg: "avg_diff_per: %d%%\n", avg_diff_per);
43 ksft_print_msg(msg: "Span (MB): %zu\n", span / MB);
44 ksft_print_msg(msg: "avg_bw_imc: %lu\n", avg_bw_imc);
45 ksft_print_msg(msg: "avg_bw_resc: %lu\n", avg_bw_resc);
46
47 return ret;
48}
49
50static int check_results(size_t span)
51{
52 unsigned long bw_imc[NUM_OF_RUNS], bw_resc[NUM_OF_RUNS];
53 char temp[1024], *token_array[8];
54 char output[] = RESULT_FILE_NAME;
55 int runs, ret;
56 FILE *fp;
57
58 ksft_print_msg(msg: "Checking for pass/fail\n");
59
60 fp = fopen(output, "r");
61 if (!fp) {
62 ksft_perror(msg: output);
63
64 return -1;
65 }
66
67 runs = 0;
68 while (fgets(temp, sizeof(temp), fp)) {
69 char *token = strtok(temp, ":\t");
70 int i = 0;
71
72 while (token) {
73 token_array[i++] = token;
74 token = strtok(NULL, ":\t");
75 }
76
77 bw_resc[runs] = strtoul(token_array[5], NULL, 0);
78 bw_imc[runs] = strtoul(token_array[3], NULL, 0);
79 runs++;
80 }
81
82 ret = show_bw_info(bw_imc, bw_resc, span);
83
84 fclose(fp);
85
86 return ret;
87}
88
89static int mbm_setup(const struct resctrl_test *test,
90 const struct user_params *uparams,
91 struct resctrl_val_param *p)
92{
93 int ret = 0;
94
95 /* Run NUM_OF_RUNS times */
96 if (p->num_of_runs >= NUM_OF_RUNS)
97 return END_OF_TESTS;
98
99 /* Set up shemata with 100% allocation on the first run. */
100 if (p->num_of_runs == 0 && resctrl_resource_exists(resource: "MB"))
101 ret = write_schemata(ctrlgrp: p->ctrlgrp, schemata: "100", cpu_no: uparams->cpu, resource: test->resource);
102
103 p->num_of_runs++;
104
105 return ret;
106}
107
108void mbm_test_cleanup(void)
109{
110 remove(RESULT_FILE_NAME);
111}
112
113static int mbm_run_test(const struct resctrl_test *test, const struct user_params *uparams)
114{
115 struct resctrl_val_param param = {
116 .resctrl_val = MBM_STR,
117 .ctrlgrp = "c1",
118 .mongrp = "m1",
119 .filename = RESULT_FILE_NAME,
120 .bw_report = "reads",
121 .setup = mbm_setup
122 };
123 int ret;
124
125 remove(RESULT_FILE_NAME);
126
127 ret = resctrl_val(test, uparams, benchmark_cmd: uparams->benchmark_cmd, param: &param);
128 if (ret)
129 goto out;
130
131 ret = check_results(DEFAULT_SPAN);
132 if (ret && (get_vendor() == ARCH_INTEL))
133 ksft_print_msg(msg: "Intel MBM may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");
134
135out:
136 mbm_test_cleanup();
137
138 return ret;
139}
140
141static bool mbm_feature_check(const struct resctrl_test *test)
142{
143 return resctrl_mon_feature_exists(resource: "L3_MON", feature: "mbm_total_bytes") &&
144 resctrl_mon_feature_exists(resource: "L3_MON", feature: "mbm_local_bytes");
145}
146
147struct resctrl_test mbm_test = {
148 .name = "MBM",
149 .resource = "MB",
150 .vendor_specific = ARCH_INTEL,
151 .feature_check = mbm_feature_check,
152 .run_test = mbm_run_test,
153};
154

source code of linux/tools/testing/selftests/resctrl/mbm_test.c