scx_simple.c

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
  4 * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
  5 * Copyright (c) 2022 David Vernet <dvernet@meta.com>
  6 */
  7#include <stdio.h>
  8#include <unistd.h>
  9#include <signal.h>
 10#include <assert.h>
 11#include <libgen.h>
 12#include <bpf/bpf.h>
 13#include <scx/common.h>
 14#include "scx_simple.bpf.skel.h"
 15
 16const char help_fmt[] =
 17"A simple sched_ext scheduler.\n"
 18"\n"
 19"See the top-level comment in .bpf.c for more details.\n"
 20"\n"
 21"Usage: %s [-f] [-v]\n"
 22"\n"
 23"  -f            Use FIFO scheduling instead of weighted vtime scheduling\n"
 24"  -v            Print libbpf debug messages\n"
 25"  -h            Display this help and exit\n";
 26
 27static bool verbose;
 28static volatile int exit_req;
 29
 30static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
 31{
 32	if (level == LIBBPF_DEBUG && !verbose)
 33		return 0;
 34	return vfprintf(stderr, format, args);
 35}
 36
 37static void sigint_handler(int simple)
 38{
 39	exit_req = 1;
 40}
 41
 42static void read_stats(struct scx_simple *skel, __u64 *stats)
 43{
 44	int nr_cpus = libbpf_num_possible_cpus();
 45	assert(nr_cpus > 0);
 46	__u64 cnts[2][nr_cpus];
 47	__u32 idx;
 48
 49	memset(stats, 0, sizeof(stats[0]) * 2);
 50
 51	for (idx = 0; idx < 2; idx++) {
 52		int ret, cpu;
 53
 54		ret = bpf_map_lookup_elem(bpf_map__fd(skel->maps.stats),
 55					  &idx, cnts[idx]);
 56		if (ret < 0)
 57			continue;
 58		for (cpu = 0; cpu < nr_cpus; cpu++)
 59			stats[idx] += cnts[idx][cpu];
 60	}
 61}
 62
 63int main(int argc, char **argv)
 64{
 65	struct scx_simple *skel;
 66	struct bpf_link *link;
 67	__u32 opt;
 68	__u64 ecode;
 69
 70	libbpf_set_print(libbpf_print_fn);
 71	signal(SIGINT, sigint_handler);
 72	signal(SIGTERM, sigint_handler);
 73restart:
 74	skel = SCX_OPS_OPEN(simple_ops, scx_simple);
 75
 76	while ((opt = getopt(argc, argv, "fvh")) != -1) {
 77		switch (opt) {
 78		case 'f':
 79			skel->rodata->fifo_sched = true;
 80			break;
 81		case 'v':
 82			verbose = true;
 83			break;
 84		default:
 85			fprintf(stderr, help_fmt, basename(argv[0]));
 86			return opt != 'h';
 87		}
 88	}
 89
 90	SCX_OPS_LOAD(skel, simple_ops, scx_simple, uei);
 91	link = SCX_OPS_ATTACH(skel, simple_ops, scx_simple);
 92
 93	while (!exit_req && !UEI_EXITED(skel, uei)) {
 94		__u64 stats[2];
 95
 96		read_stats(skel, stats);
 97		printf("local=%llu global=%llu\n", stats[0], stats[1]);
 98		fflush(stdout);
 99		sleep(1);
100	}
101
102	bpf_link__destroy(link);
103	ecode = UEI_REPORT(skel, uei);
104	scx_simple__destroy(skel);
105
106	if (UEI_ECODE_RESTART(ecode))
107		goto restart;
108	return 0;
109}