tools/sched_ext/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 <libgen.h>
  11 #include <bpf/bpf.h>
  12 #include <scx/common.h>
  13 #include "scx_simple.bpf.skel.h"
  14
  15 const char help_fmt[] =
  16 "A simple sched_ext scheduler.\n"
  17 "\n"
  18 "See the top-level comment in .bpf.c for more details.\n"
  19 "\n"
  20 "Usage: %s [-f] [-v]\n"
  21 "\n"
  22 "  -f            Use FIFO scheduling instead of weighted vtime scheduling\n"
  23 "  -v            Print libbpf debug messages\n"
  24 "  -h            Display this help and exit\n";
  25
  26 static bool verbose;
  27 static volatile int exit_req;
  28
  29 static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
  30 {
  31         if (level == LIBBPF_DEBUG && !verbose)
  32                 return 0;
  33         return vfprintf(stderr, format, args);
  34 }
  35
  36 static void sigint_handler(int simple)
  37 {
  38         exit_req = 1;
  39 }
  40
  41 static void read_stats(struct scx_simple *skel, __u64 *stats)
  42 {
  43         int nr_cpus = libbpf_num_possible_cpus();
  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
  61 int main(int argc, char **argv)
  62 {
  63         struct scx_simple *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);
  71 restart:
  72         skel = SCX_OPS_OPEN(simple_ops, scx_simple);
  73
  74         while ((opt = getopt(argc, argv, "fvh")) != -1) {
  75                 switch (opt) {
  76                 case 'f':
  77                         skel->rodata->fifo_sched = true;
  78                         break;
  79                 case 'v':
  80                         verbose = true;
  81                         break;
  82                 default:
  83                         fprintf(stderr, help_fmt, basename(argv[0]));
  84                         return opt != 'h';
  85                 }
  86         }
  87
  88         SCX_OPS_LOAD(skel, simple_ops, scx_simple, uei);
  89         link = SCX_OPS_ATTACH(skel, simple_ops, scx_simple);
  90
  91         while (!exit_req && !UEI_EXITED(skel, uei)) {
  92                 __u64 stats[2];
  93
  94                 read_stats(skel, stats);
  95                 printf("local=%llu global=%llu\n", stats[0], stats[1]);
  96                 fflush(stdout);
  97                 sleep(1);
  98         }
  99
 100         bpf_link__destroy(link);
 101         ecode = UEI_REPORT(skel, uei);
 102         scx_simple__destroy(skel);
 103
 104         if (UEI_ECODE_RESTART(ecode))
 105                 goto restart;
 106         return 0;
 107 }