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https://github.com/eunomia-bpf/bpf-developer-tutorial.git
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118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
// 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_core_read.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "runqslower.bpf.h"
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#include "core_fixes.h"
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#define TASK_RUNNING 0
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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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const volatile pid_t targ_tgid = 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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static int trace_enqueue(u32 tgid, u32 pid)
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{
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u64 ts;
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if (!pid)
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return 0;
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if (targ_tgid && targ_tgid != tgid)
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return 0;
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if (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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static int handle_switch(void *ctx, struct task_struct *prev, struct task_struct *next)
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{
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struct event event = {};
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u64 *tsp, delta_us;
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u32 pid;
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/* ivcsw: treat like an enqueue event and store timestamp */
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if (get_task_state(prev) == TASK_RUNNING)
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trace_enqueue(BPF_CORE_READ(prev, tgid), BPF_CORE_READ(prev, pid));
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pid = BPF_CORE_READ(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.prev_pid = BPF_CORE_READ(prev, pid);
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event.delta_us = delta_us;
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bpf_probe_read_kernel_str(&event.task, sizeof(event.task), next->comm);
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bpf_probe_read_kernel_str(&event.prev_task, sizeof(event.prev_task), prev->comm);
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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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SEC("tp_btf/sched_wakeup")
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int BPF_PROG(sched_wakeup, struct task_struct *p)
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{
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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 BPF_PROG(sched_wakeup_new, struct task_struct *p)
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{
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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 BPF_PROG(sched_switch, bool preempt, struct task_struct *prev, struct task_struct *next)
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{
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return handle_switch(ctx, prev, next);
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}
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SEC("raw_tp/sched_wakeup")
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int BPF_PROG(handle_sched_wakeup, struct task_struct *p)
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{
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return trace_enqueue(BPF_CORE_READ(p, tgid), BPF_CORE_READ(p, pid));
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}
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SEC("raw_tp/sched_wakeup_new")
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int BPF_PROG(handle_sched_wakeup_new, struct task_struct *p)
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{
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return trace_enqueue(BPF_CORE_READ(p, tgid), BPF_CORE_READ(p, pid));
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}
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SEC("raw_tp/sched_switch")
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int BPF_PROG(handle_sched_switch, bool preempt, struct task_struct *prev, struct task_struct *next)
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{
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return handle_switch(ctx, prev, next);
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}
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char LICENSE[] SEC("license") = "GPL";
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