scx_cpu0.c

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Copyright (c) 2025 Meta Platforms, Inc. and affiliates.
  4 * Copyright (c) 2025 Tejun Heo <tj@kernel.org>
  5 */
  6#include <stdio.h>
  7#include <unistd.h>
  8#include <signal.h>
  9#include <assert.h>
 10#include <libgen.h>
 11#include <bpf/bpf.h>
 12#include <scx/common.h>
 13#include "scx_cpu0.bpf.skel.h"
 14
 15const char help_fmt[] =
 16"A cpu0 sched_ext scheduler.\n"
 17"\n"
 18"See the top-level comment in .bpf.c for more details.\n"
 19"\n"
 20"Usage: %s [-v]\n"
 21"\n"
 22"  -v            Print libbpf debug messages\n"
 23"  -h            Display this help and exit\n";
 24
 25static bool verbose;
 26static volatile int exit_req;
 27
 28static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
 29{
 30	if (level == LIBBPF_DEBUG && !verbose)
 31		return 0;
 32	return vfprintf(stderr, format, args);
 33}
 34
 35static void sigint_handler(int sig)
 36{
 37	exit_req = 1;
 38}
 39
 40static void read_stats(struct scx_cpu0 *skel, __u64 *stats)
 41{
 42	int nr_cpus = libbpf_num_possible_cpus();
 43	assert(nr_cpus > 0);
 44	__u64 cnts[2][nr_cpus];
 45	__u32 idx;
 46
 47	memset(stats, 0, sizeof(stats[0]) * 2);
 48
 49	for (idx = 0; idx < 2; idx++) {
 50		int ret, cpu;
 51
 52		ret = bpf_map_lookup_elem(bpf_map__fd(skel->maps.stats),
 53					  &idx, cnts[idx]);
 54		if (ret < 0)
 55			continue;
 56		for (cpu = 0; cpu < nr_cpus; cpu++)
 57			stats[idx] += cnts[idx][cpu];
 58	}
 59}
 60
 61int main(int argc, char **argv)
 62{
 63	struct scx_cpu0 *skel;
 64	struct bpf_link *link;
 65	__u32 opt;
 66	__u64 ecode;
 67
 68	libbpf_set_print(libbpf_print_fn);
 69	signal(SIGINT, sigint_handler);
 70	signal(SIGTERM, sigint_handler);
 71restart:
 72	skel = SCX_OPS_OPEN(cpu0_ops, scx_cpu0);
 73
 74	skel->rodata->nr_cpus = libbpf_num_possible_cpus();
 75
 76	while ((opt = getopt(argc, argv, "vh")) != -1) {
 77		switch (opt) {
 78		case 'v':
 79			verbose = true;
 80			break;
 81		default:
 82			fprintf(stderr, help_fmt, basename(argv[0]));
 83			return opt != 'h';
 84		}
 85	}
 86
 87	SCX_OPS_LOAD(skel, cpu0_ops, scx_cpu0, uei);
 88	link = SCX_OPS_ATTACH(skel, cpu0_ops, scx_cpu0);
 89
 90	while (!exit_req && !UEI_EXITED(skel, uei)) {
 91		__u64 stats[2];
 92
 93		read_stats(skel, stats);
 94		printf("local=%llu cpu0=%llu\n", stats[0], stats[1]);
 95		fflush(stdout);
 96		sleep(1);
 97	}
 98
 99	bpf_link__destroy(link);
100	ecode = UEI_REPORT(skel, uei);
101	scx_cpu0__destroy(skel);
102
103	if (UEI_ECODE_RESTART(ecode))
104		goto restart;
105	return 0;
106}