1 /*
2 * Copyright (c) 2018 Google, Inc.
3 *
4 * SPDX-License-Identifier: GPL-2.0-or-later
5 *
6 * A task executes as small then as big. Upmigration latency and task placement
7 * are verified.
8 */
9
10 #define _GNU_SOURCE
11 #include <errno.h>
12 #include <pthread.h>
13 #include <sched.h>
14 #include <sys/types.h>
15 #include <time.h>
16
17 #include "tst_test.h"
18 #include "tst_safe_file_ops.h"
19 #include "tst_safe_pthread.h"
20
21 #include "trace_parse.h"
22 #include "util.h"
23
24 #define TRACE_EVENTS "sched_switch"
25
26 static int task_tid;
27
28 #define MAX_UPMIGRATE_LATENCY_US 100000
29 #define MAX_INCORRECT_CLUSTER_PCT 10
30 #define BURN_SEC 3
task_fn(void * arg LTP_ATTRIBUTE_UNUSED)31 static void *task_fn(void *arg LTP_ATTRIBUTE_UNUSED)
32 {
33 task_tid = gettid();
34
35 printf("Small task executing for %ds...\n", BURN_SEC);
36 burn(BURN_SEC * USEC_PER_SEC, 1);
37
38 printf("Changing to big task...\n");
39 SAFE_FILE_PRINTF(TRACING_DIR "trace_marker", "CPU HOG");
40 burn(BURN_SEC * USEC_PER_SEC, 0);
41
42 return NULL;
43 }
44
parse_results(void)45 static int parse_results(void)
46 {
47 int i, pct, rv = 0;
48 unsigned long long exec_start_us = 0;
49 unsigned long long too_big_cpu_us = 0;
50 unsigned long long too_small_cpu_us = 0;
51 unsigned long long small_task_us = 0;
52 unsigned long long big_task_us = 0;
53 unsigned long long cpuhog_ts_usec = 0;
54 unsigned long long upmigrate_ts_usec = 0;
55 unsigned long long upmigrate_latency_usec = 0;
56 cpu_set_t cpuset;
57
58 if (find_cpus_with_capacity(0, &cpuset)) {
59 printf("Failed to find the CPUs in the little cluster.\n");
60 return -1;
61 }
62
63 for (i = 0; i < num_trace_records; i++) {
64 unsigned long long segment_us;
65 struct trace_sched_switch *t = trace[i].event_data;
66
67 if (trace[i].event_type == TRACE_RECORD_TRACING_MARK_WRITE &&
68 !strcmp(trace[i].event_data, "CPU HOG")) {
69 cpuhog_ts_usec = TS_TO_USEC(trace[i].ts);
70 continue;
71 }
72
73 if (trace[i].event_type != TRACE_RECORD_SCHED_SWITCH)
74 continue;
75 if (t->next_pid == task_tid) {
76 /* Start of task execution segment. */
77 if (exec_start_us) {
78 printf("Trace parse fail: double exec start\n");
79 return -1;
80 }
81 exec_start_us = TS_TO_USEC(trace[i].ts);
82 if (cpuhog_ts_usec && !upmigrate_ts_usec &&
83 !CPU_ISSET(trace[i].cpu, &cpuset))
84 upmigrate_ts_usec = exec_start_us;
85 continue;
86 }
87 if (t->prev_pid != task_tid)
88 continue;
89 /* End of task execution segment. */
90 segment_us = TS_TO_USEC(trace[i].ts);
91 segment_us -= exec_start_us;
92 exec_start_us = 0;
93 if (CPU_ISSET(trace[i].cpu, &cpuset)) {
94 /* Task is running on little CPUs. */
95 if (cpuhog_ts_usec) {
96 /*
97 * Upmigration is accounted separately, so only
98 * record mis-scheduled time here if it happened
99 * after upmigration.
100 */
101 if (upmigrate_ts_usec)
102 too_small_cpu_us += segment_us;
103 }
104 } else {
105 /* Task is running on big CPUs. */
106 if (!cpuhog_ts_usec)
107 too_big_cpu_us += segment_us;
108 }
109 if (cpuhog_ts_usec)
110 big_task_us += segment_us;
111 else
112 small_task_us += segment_us;
113 }
114
115 pct = (too_big_cpu_us * 100) / small_task_us;
116 rv |= (pct > MAX_INCORRECT_CLUSTER_PCT);
117 printf("Time incorrectly scheduled on big when task was small: "
118 "%lld usec (%d%% of small task CPU time)\n", too_big_cpu_us,
119 pct);
120 pct = (too_small_cpu_us * 100) / big_task_us;
121 rv |= (pct > MAX_INCORRECT_CLUSTER_PCT);
122 printf("Time incorrectly scheduled on small when task was big, "
123 "after upmigration: "
124 "%lld usec (%d%% of big task CPU time)\n", too_small_cpu_us,
125 pct);
126
127 if (upmigrate_ts_usec) {
128 upmigrate_latency_usec = upmigrate_ts_usec - cpuhog_ts_usec;
129 printf("Upmigration latency: %lld usec\n",
130 upmigrate_latency_usec);
131 } else {
132 printf("Task never upmigrated!\n");
133 upmigrate_latency_usec = UINT_MAX;
134 }
135
136 return (rv || upmigrate_latency_usec > MAX_UPMIGRATE_LATENCY_US);
137 }
138
run(void)139 static void run(void)
140 {
141 pthread_t task_thread;
142
143 tst_res(TINFO, "Maximum incorrect cluster time percentage: %d%%",
144 MAX_INCORRECT_CLUSTER_PCT);
145 tst_res(TINFO, "Maximum upmigration latency: %d usec",
146 MAX_UPMIGRATE_LATENCY_US);
147
148 /* configure and enable tracing */
149 SAFE_FILE_PRINTF(TRACING_DIR "tracing_on", "0");
150 SAFE_FILE_PRINTF(TRACING_DIR "buffer_size_kb", "16384");
151 SAFE_FILE_PRINTF(TRACING_DIR "set_event", TRACE_EVENTS);
152 SAFE_FILE_PRINTF(TRACING_DIR "trace", "\n");
153 SAFE_FILE_PRINTF(TRACING_DIR "tracing_on", "1");
154
155 SAFE_PTHREAD_CREATE(&task_thread, NULL, task_fn, NULL);
156 SAFE_PTHREAD_JOIN(task_thread, NULL);
157
158 /* disable tracing */
159 SAFE_FILE_PRINTF(TRACING_DIR "tracing_on", "0");
160 LOAD_TRACE();
161
162 if (parse_results())
163 tst_res(TFAIL, "Task placement and migration latency goals "
164 "were not met.\n");
165 else
166 tst_res(TPASS, "Task placement and migration latency goals "
167 "were met.\n");
168 }
169
170 static struct tst_test test = {
171 .test_all = run,
172 .cleanup = trace_cleanup,
173 };
174