// SPDX-License-Identifier: GPL-2.0
/*
 * scx_perfprobe - samples per-CPU rq->scx.cpuperf_target (the value
 * schedutil consumes). Kprobes sched_tick and overwrites this CPU's
 * bucket on every tick (~1000/s at HZ=1000).
 */
#include <scx/common.bpf.h>

char _license[] SEC("license") = "GPL";

#define K2_MAX_CPUS 128

struct {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, K2_MAX_CPUS);
	__type(key, u32);
	__type(value, u64);
} targets SEC(".maps");

/* per-CPU sched_tick hits: tells whether a CPU is really running ticks */
struct {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, K2_MAX_CPUS);
	__type(key, u32);
	__type(value, u64);
} tickcnt SEC(".maps");

SEC("kprobe/sched_tick")
int BPF_KPROBE(k2_sample_tick)
{
	struct rq *rq = bpf_this_cpu_ptr(&runqueues);
	/* map value is u64: read the target into a u64 so we don't pass
	 * a u32 address as an 8-byte value */
	u64 t = rq->scx.cpuperf_target;
	u32 cpu = bpf_get_smp_processor_id();

	if (cpu < K2_MAX_CPUS)
		bpf_map_update_elem(&targets, &cpu, &t, BPF_ANY);
	return 0;
}