// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2019 Facebook
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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#include "runqslower.h"
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#define TASK_RUNNING 0
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#define BPF_F_CURRENT_CPU 0xffffffffULL
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const volatile __u64 min_us = 0;
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const volatile pid_t targ_pid = 0;
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, 10240);
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__type(key, u32);
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__type(value, u64);
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} start SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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__uint(key_size, sizeof(u32));
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__uint(value_size, sizeof(u32));
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} events SEC(".maps");
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/* record enqueue timestamp */
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__always_inline
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static int trace_enqueue(u32 tgid, u32 pid)
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{
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u64 ts;
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if (!pid || (targ_pid && targ_pid != pid))
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return 0;
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ts = bpf_ktime_get_ns();
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bpf_map_update_elem(&start, &pid, &ts, 0);
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return 0;
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}
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SEC("tp_btf/sched_wakeup")
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int handle__sched_wakeup(u64 *ctx)
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{
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/* TP_PROTO(struct task_struct *p) */
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struct task_struct *p = (void *)ctx[0];
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return trace_enqueue(p->tgid, p->pid);
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}
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SEC("tp_btf/sched_wakeup_new")
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int handle__sched_wakeup_new(u64 *ctx)
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{
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/* TP_PROTO(struct task_struct *p) */
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struct task_struct *p = (void *)ctx[0];
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return trace_enqueue(p->tgid, p->pid);
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}
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SEC("tp_btf/sched_switch")
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int handle__sched_switch(u64 *ctx)
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{
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/* TP_PROTO(bool preempt, struct task_struct *prev,
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* struct task_struct *next)
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*/
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struct task_struct *prev = (struct task_struct *)ctx[1];
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struct task_struct *next = (struct task_struct *)ctx[2];
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struct event event = {};
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u64 *tsp, delta_us;
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long state;
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u32 pid;
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/* ivcsw: treat like an enqueue event and store timestamp */
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if (prev->state == TASK_RUNNING)
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trace_enqueue(prev->tgid, prev->pid);
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pid = next->pid;
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/* fetch timestamp and calculate delta */
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tsp = bpf_map_lookup_elem(&start, &pid);
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if (!tsp)
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return 0; /* missed enqueue */
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delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
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if (min_us && delta_us <= min_us)
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return 0;
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event.pid = pid;
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event.delta_us = delta_us;
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bpf_get_current_comm(&event.task, sizeof(event.task));
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/* output */
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bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
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&event, sizeof(event));
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bpf_map_delete_elem(&start, &pid);
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return 0;
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}
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char LICENSE[] SEC("license") = "GPL";
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