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// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
// Copyright (c) 2021 Facebook
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(int));
__uint(map_flags, BPF_F_PRESERVE_ELEMS);
} events SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(struct bpf_perf_event_value));
__uint(max_entries, 1);
} prev_readings SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(struct bpf_perf_event_value));
__uint(max_entries, 1);
} diff_readings SEC(".maps");
SEC("raw_tp/sched_switch")
int BPF_PROG(on_switch)
{
struct bpf_perf_event_value val, *prev_val, *diff_val;
__u32 key = bpf_get_smp_processor_id();
__u32 zero = 0;
long err;
prev_val = bpf_map_lookup_elem(&prev_readings, &zero);
if (!prev_val)
return 0;
diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
if (!diff_val)
return 0;
err = bpf_perf_event_read_value(&events, key, &val, sizeof(val));
if (err)
return 0;
diff_val->counter = val.counter - prev_val->counter;
diff_val->enabled = val.enabled - prev_val->enabled;
diff_val->running = val.running - prev_val->running;
*prev_val = val;
return 0;
}
char LICENSE[] SEC("license") = "Dual BSD/GPL";
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