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 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