1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Facebook
3 #include "vmlinux.h"
4 #include <bpf/bpf_helpers.h>
5 #include "runqslower.h"
6
7 #define TASK_RUNNING 0
8 #define BPF_F_CURRENT_CPU 0xffffffffULL
9
10 const volatile __u64 min_us = 0;
11 const volatile pid_t targ_pid = 0;
12
13 struct {
14 __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
15 __uint(map_flags, BPF_F_NO_PREALLOC);
16 __type(key, int);
17 __type(value, u64);
18 } start SEC(".maps");
19
20 struct {
21 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
22 __uint(key_size, sizeof(u32));
23 __uint(value_size, sizeof(u32));
24 } events SEC(".maps");
25
26 /* record enqueue timestamp */
27 __always_inline
28 static int trace_enqueue(struct task_struct *t)
29 {
30 u32 pid = t->pid;
31 u64 *ptr;
32
33 if (!pid || (targ_pid && targ_pid != pid))
34 return 0;
35
36 ptr = bpf_task_storage_get(&start, t, 0,
37 BPF_LOCAL_STORAGE_GET_F_CREATE);
38 if (!ptr)
39 return 0;
40
41 *ptr = bpf_ktime_get_ns();
42 return 0;
43 }
44
45 SEC("tp_btf/sched_wakeup")
46 int handle__sched_wakeup(u64 *ctx)
47 {
48 /* TP_PROTO(struct task_struct *p) */
49 struct task_struct *p = (void *)ctx[0];
50
51 return trace_enqueue(p);
52 }
53
54 SEC("tp_btf/sched_wakeup_new")
55 int handle__sched_wakeup_new(u64 *ctx)
56 {
57 /* TP_PROTO(struct task_struct *p) */
58 struct task_struct *p = (void *)ctx[0];
59
60 return trace_enqueue(p);
61 }
62
63 SEC("tp_btf/sched_switch")
64 int handle__sched_switch(u64 *ctx)
65 {
66 /* TP_PROTO(bool preempt, struct task_struct *prev,
67 * struct task_struct *next)
68 */
69 struct task_struct *prev = (struct task_struct *)ctx[1];
70 struct task_struct *next = (struct task_struct *)ctx[2];
71 struct runq_event event = {};
72 u64 *tsp, delta_us;
73 long state;
74 u32 pid;
75
76 /* ivcsw: treat like an enqueue event and store timestamp */
77 if (prev->__state == TASK_RUNNING)
78 trace_enqueue(prev);
79
80 pid = next->pid;
81
82 /* For pid mismatch, save a bpf_task_storage_get */
83 if (!pid || (targ_pid && targ_pid != pid))
84 return 0;
85
86 /* fetch timestamp and calculate delta */
87 tsp = bpf_task_storage_get(&start, next, 0, 0);
88 if (!tsp)
89 return 0; /* missed enqueue */
90
91 delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
92 if (min_us && delta_us <= min_us)
93 return 0;
94
95 event.pid = pid;
96 event.delta_us = delta_us;
97 bpf_get_current_comm(&event.task, sizeof(event.task));
98
99 /* output */
100 bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
101 &event, sizeof(event));
102
103 bpf_task_storage_delete(&start, next);
104 return 0;
105 }
106
107 char LICENSE[] SEC("license") = "GPL";
108
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