/*
* Copyright (c) 2018 Google, Inc.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* A task alternates between being big and small. Max up and down migration
* latencies and task placement are verified.
*/
#define _GNU_SOURCE
#include <errno.h>
#include <pthread.h>
#include <sched.h>
#include <time.h>
#include "tst_test.h"
#include "tst_safe_file_ops.h"
#include "tst_safe_pthread.h"
#include "trace_parse.h"
#include "util.h"
#define TRACE_EVENTS "sched_switch"
static int task_tid;
#define MAX_UPMIGRATE_LATENCY_US 100000
#define MAX_DOWNMIGRATE_LATENCY_US 100000
#define MAX_INCORRECT_CLUSTER_PCT 10
#define BURN_SEC 1
#define NUM_LOOPS 10
static void *task_fn(void *arg LTP_ATTRIBUTE_UNUSED)
{
int loops = NUM_LOOPS;
task_tid = gettid();
while (loops--) {
SAFE_FILE_PRINTF(TRACING_DIR "trace_marker", "SMALL TASK");
burn(BURN_SEC * USEC_PER_SEC, 1);
SAFE_FILE_PRINTF(TRACING_DIR "trace_marker", "CPU HOG");
burn(BURN_SEC * USEC_PER_SEC, 0);
}
return NULL;
}
static int parse_results(void)
{
int i, pct, rv = 0;
unsigned long long exec_start_us = 0;
unsigned long long too_big_cpu_us = 0;
unsigned long long too_small_cpu_us = 0;
unsigned long long small_task_us = 0;
unsigned long long big_task_us = 0;
unsigned long long smalltask_ts_usec = 0;
unsigned long long cpuhog_ts_usec = 0;
unsigned long long upmigrate_ts_usec = 0;
unsigned long long downmigrate_ts_usec = 0;
unsigned long long max_upmigrate_latency_usec = 0;
unsigned long long max_downmigrate_latency_usec = 0;
cpu_set_t cpuset;
if (find_cpus_with_capacity(0, &cpuset)) {
printf("Failed to find the CPUs in the little cluster.\n");
return -1;
}
for (i = 0; i < num_trace_records; i++) {
unsigned long long segment_us;
struct trace_sched_switch *t = trace[i].event_data;
if (trace[i].event_type == TRACE_RECORD_TRACING_MARK_WRITE) {
if (!strcmp(trace[i].event_data, "CPU HOG")) {
/* Task is transitioning to cpu hog. */
cpuhog_ts_usec = TS_TO_USEC(trace[i].ts);
if (downmigrate_ts_usec) {
unsigned long long temp_latency;
temp_latency = downmigrate_ts_usec -
smalltask_ts_usec;
if (temp_latency >
max_downmigrate_latency_usec)
max_downmigrate_latency_usec =
temp_latency;
} else if (smalltask_ts_usec) {
printf("Warning: small task never "
"downmigrated.\n");
rv = 1;
}
downmigrate_ts_usec = 0;
smalltask_ts_usec = 0;
} else if (!strcmp(trace[i].event_data, "SMALL TASK")) {
smalltask_ts_usec = TS_TO_USEC(trace[i].ts);
if (upmigrate_ts_usec) {
unsigned long long temp_latency;
temp_latency = upmigrate_ts_usec -
cpuhog_ts_usec;
if (temp_latency >
max_upmigrate_latency_usec)
max_upmigrate_latency_usec =
temp_latency;
} else if (cpuhog_ts_usec) {
printf("Warning: big task never "
"upmigrated.\n");
rv = 1;
}
upmigrate_ts_usec = 0;
cpuhog_ts_usec = 0;
}
continue;
}
if (trace[i].event_type != TRACE_RECORD_SCHED_SWITCH)
continue;
if (t->next_pid == task_tid) {
/* Start of task execution segment. */
if (exec_start_us) {
printf("Trace parse fail: double exec start\n");
return -1;
}
exec_start_us = TS_TO_USEC(trace[i].ts);
if (cpuhog_ts_usec && !upmigrate_ts_usec &&
!CPU_ISSET(trace[i].cpu, &cpuset))
upmigrate_ts_usec = exec_start_us;
if (smalltask_ts_usec && !downmigrate_ts_usec &&
CPU_ISSET(trace[i].cpu, &cpuset))
downmigrate_ts_usec = exec_start_us;
continue;
}
if (t->prev_pid != task_tid)
continue;
/* End of task execution segment. */
segment_us = TS_TO_USEC(trace[i].ts);
segment_us -= exec_start_us;
exec_start_us = 0;
if (CPU_ISSET(trace[i].cpu, &cpuset)) {
/* Task is running on little CPUs. */
if (cpuhog_ts_usec) {
/*
* Upmigration is accounted separately, so only
* record mis-scheduled time here if it happened
* after upmigration.
*/
if (upmigrate_ts_usec)
too_small_cpu_us += segment_us;
}
} else {
/* Task is running on big CPUs. */
if (smalltask_ts_usec) {
/*
* Downmigration is accounted separately, so
* only record mis-scheduled time here if it
* happened after downmigration.
*/
if (downmigrate_ts_usec)
too_big_cpu_us += segment_us;
}
}
if (cpuhog_ts_usec)
big_task_us += segment_us;
if (smalltask_ts_usec)
small_task_us += segment_us;
}
pct = (too_big_cpu_us * 100) / small_task_us;
rv |= (pct > MAX_INCORRECT_CLUSTER_PCT);
printf("Time incorrectly scheduled on big when task was small, "
"after downmigration: "
"%lld usec (%d%% of small task CPU time)\n", too_big_cpu_us,
pct);
pct = (too_small_cpu_us * 100) / big_task_us;
rv |= (pct > MAX_INCORRECT_CLUSTER_PCT);
printf("Time incorrectly scheduled on small when task was big, "
"after upmigration: "
"%lld usec (%d%% of big task CPU time)\n", too_small_cpu_us,
pct);
printf("small task time: %lld\nbig task time: %lld\n",
small_task_us, big_task_us);
printf("Maximum upmigration time: %lld\n",
max_upmigrate_latency_usec);
printf("Maximum downmigration time: %lld\n",
max_downmigrate_latency_usec);
return (rv ||
max_upmigrate_latency_usec > MAX_UPMIGRATE_LATENCY_US ||
max_downmigrate_latency_usec > MAX_DOWNMIGRATE_LATENCY_US);
}
static void run(void)
{
pthread_t task_thread;
tst_res(TINFO, "Maximum incorrect cluster time percentage: %d%%",
MAX_INCORRECT_CLUSTER_PCT);
tst_res(TINFO, "Maximum downmigration latency: %d usec",
MAX_DOWNMIGRATE_LATENCY_US);
tst_res(TINFO, "Maximum upmigration latency: %d usec",
MAX_UPMIGRATE_LATENCY_US);
printf("Task alternating between big and small for %d sec\n",
BURN_SEC * NUM_LOOPS * 2);
/* configure and enable tracing */
SAFE_FILE_PRINTF(TRACING_DIR "tracing_on", "0");
SAFE_FILE_PRINTF(TRACING_DIR "buffer_size_kb", "16384");
SAFE_FILE_PRINTF(TRACING_DIR "set_event", TRACE_EVENTS);
SAFE_FILE_PRINTF(TRACING_DIR "trace", "\n");
SAFE_FILE_PRINTF(TRACING_DIR "tracing_on", "1");
SAFE_PTHREAD_CREATE(&task_thread, NULL, task_fn, NULL);
SAFE_PTHREAD_JOIN(task_thread, NULL);
/* disable tracing */
SAFE_FILE_PRINTF(TRACING_DIR "tracing_on", "0");
LOAD_TRACE();
if (parse_results())
tst_res(TFAIL, "Task placement and migration latency goals "
"were not met.\n");
else
tst_res(TPASS, "Task placement and migration latency goals "
"were met.\n");
}
static struct tst_test test = {
.test_all = run,
.cleanup = trace_cleanup,
};