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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
* Copyright (c) 2022 Tejun Heo <tj@kernel.org>
* Copyright (c) 2022 David Vernet <dvernet@meta.com>
*/
#include <stdio.h>
#include <unistd.h>
#include <inttypes.h>
#include <signal.h>
#include <assert.h>
#include <libgen.h>
#include <bpf/bpf.h>
#include <scx/common.h>
#include "scx_pair.h"
#include "scx_pair.bpf.skel.h"
const char help_fmt[] =
"A demo sched_ext core-scheduler which always makes every sibling CPU pair\n"
"execute from the same CPU cgroup.\n"
"\n"
"See the top-level comment in .bpf.c for more details.\n"
"\n"
"Usage: %s [-S STRIDE]\n"
"\n"
" -S STRIDE Override CPU pair stride (default: nr_cpus_ids / 2)\n"
" -v Print libbpf debug messages\n"
" -h Display this help and exit\n";
static bool verbose;
static volatile int exit_req;
static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
{
if (level == LIBBPF_DEBUG && !verbose)
return 0;
return vfprintf(stderr, format, args);
}
static void sigint_handler(int dummy)
{
exit_req = 1;
}
int main(int argc, char **argv)
{
struct scx_pair *skel;
struct bpf_link *link;
__u64 seq = 0, ecode;
__s32 stride, i, opt, outer_fd;
libbpf_set_print(libbpf_print_fn);
signal(SIGINT, sigint_handler);
signal(SIGTERM, sigint_handler);
restart:
optind = 1;
skel = SCX_OPS_OPEN(pair_ops, scx_pair);
skel->rodata->nr_cpu_ids = libbpf_num_possible_cpus();
skel->rodata->pair_batch_dur_ns = __COMPAT_ENUM_OR_ZERO("scx_public_consts", "SCX_SLICE_DFL");
/* pair up the earlier half to the latter by default, override with -s */
stride = skel->rodata->nr_cpu_ids / 2;
while ((opt = getopt(argc, argv, "S:vh")) != -1) {
switch (opt) {
case 'S':
stride = strtoul(optarg, NULL, 0);
break;
case 'v':
verbose = true;
break;
default:
fprintf(stderr, help_fmt, basename(argv[0]));
return opt != 'h';
}
}
/* Stride must be positive to pair distinct CPUs. */
if (stride <= 0) {
fprintf(stderr, "Invalid stride %d, must be positive\n", stride);
scx_pair__destroy(skel);
return -1;
}
bpf_map__set_max_entries(skel->maps.pair_ctx, skel->rodata->nr_cpu_ids / 2);
/* Resize arrays so their element count is equal to cpu count. */
RESIZE_ARRAY(skel, rodata, pair_cpu, skel->rodata->nr_cpu_ids);
RESIZE_ARRAY(skel, rodata, pair_id, skel->rodata->nr_cpu_ids);
RESIZE_ARRAY(skel, rodata, in_pair_idx, skel->rodata->nr_cpu_ids);
for (i = 0; i < skel->rodata->nr_cpu_ids; i++)
skel->rodata_pair_cpu->pair_cpu[i] = -1;
printf("Pairs: ");
for (i = 0; i < skel->rodata->nr_cpu_ids; i++) {
int j = (i + stride) % skel->rodata->nr_cpu_ids;
if (skel->rodata_pair_cpu->pair_cpu[i] >= 0)
continue;
SCX_BUG_ON(i == j,
"Invalid stride %d - CPU%d wants to be its own pair",
stride, i);
SCX_BUG_ON(skel->rodata_pair_cpu->pair_cpu[j] >= 0,
"Invalid stride %d - three CPUs (%d, %d, %d) want to be a pair",
stride, i, j, skel->rodata_pair_cpu->pair_cpu[j]);
skel->rodata_pair_cpu->pair_cpu[i] = j;
skel->rodata_pair_cpu->pair_cpu[j] = i;
skel->rodata_pair_id->pair_id[i] = i;
skel->rodata_pair_id->pair_id[j] = i;
skel->rodata_in_pair_idx->in_pair_idx[i] = 0;
skel->rodata_in_pair_idx->in_pair_idx[j] = 1;
printf("[%d, %d] ", i, j);
}
printf("\n");
SCX_OPS_LOAD(skel, pair_ops, scx_pair, uei);
/*
* Populate the cgrp_q_arr map which is an array containing per-cgroup
* queues. It'd probably be better to do this from BPF but there are too
* many to initialize statically and there's no way to dynamically
* populate from BPF.
*/
outer_fd = bpf_map__fd(skel->maps.cgrp_q_arr);
SCX_BUG_ON(outer_fd < 0, "Failed to get outer_fd: %d", outer_fd);
printf("Initializing");
for (i = 0; i < MAX_CGRPS; i++) {
__s32 inner_fd;
if (exit_req)
break;
inner_fd = bpf_map_create(BPF_MAP_TYPE_QUEUE, NULL, 0,
sizeof(__u32), MAX_QUEUED, NULL);
SCX_BUG_ON(inner_fd < 0, "Failed to get inner_fd: %d",
inner_fd);
SCX_BUG_ON(bpf_map_update_elem(outer_fd, &i, &inner_fd, BPF_ANY),
"Failed to set inner map");
close(inner_fd);
if (!(i % 10))
printf(".");
fflush(stdout);
}
printf("\n");
/*
* Fully initialized, attach and run.
*/
link = SCX_OPS_ATTACH(skel, pair_ops, scx_pair);
while (!exit_req && !UEI_EXITED(skel, uei)) {
printf("[SEQ %llu]\n", seq++);
printf(" total:%10" PRIu64 " dispatch:%10" PRIu64 " missing:%10" PRIu64 "\n",
skel->bss->nr_total,
skel->bss->nr_dispatched,
skel->bss->nr_missing);
printf(" kicks:%10" PRIu64 " preemptions:%7" PRIu64 "\n",
skel->bss->nr_kicks,
skel->bss->nr_preemptions);
printf(" exp:%10" PRIu64 " exp_wait:%10" PRIu64 " exp_empty:%10" PRIu64 "\n",
skel->bss->nr_exps,
skel->bss->nr_exp_waits,
skel->bss->nr_exp_empty);
printf("cgnext:%10" PRIu64 " cgcoll:%10" PRIu64 " cgempty:%10" PRIu64 "\n",
skel->bss->nr_cgrp_next,
skel->bss->nr_cgrp_coll,
skel->bss->nr_cgrp_empty);
fflush(stdout);
sleep(1);
}
bpf_link__destroy(link);
ecode = UEI_REPORT(skel, uei);
scx_pair__destroy(skel);
if (UEI_ECODE_RESTART(ecode))
goto restart;
return 0;
}
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