142 lines · c
1/* Copyright (c) 2016 Facebook2 *3 * This program is free software; you can redistribute it and/or4 * modify it under the terms of version 2 of the GNU General Public5 * License as published by the Free Software Foundation.6 */7#include "vmlinux.h"8#include <linux/version.h>9#include <bpf/bpf_helpers.h>10#include <bpf/bpf_tracing.h>11#include <bpf/bpf_core_read.h>12 13#ifndef PERF_MAX_STACK_DEPTH14#define PERF_MAX_STACK_DEPTH 12715#endif16 17#define MINBLOCK_US 118#define MAX_ENTRIES 1000019 20struct key_t {21 char waker[TASK_COMM_LEN];22 char target[TASK_COMM_LEN];23 u32 wret;24 u32 tret;25};26 27struct {28 __uint(type, BPF_MAP_TYPE_HASH);29 __type(key, struct key_t);30 __type(value, u64);31 __uint(max_entries, MAX_ENTRIES);32} counts SEC(".maps");33 34struct {35 __uint(type, BPF_MAP_TYPE_HASH);36 __type(key, u32);37 __type(value, u64);38 __uint(max_entries, MAX_ENTRIES);39} start SEC(".maps");40 41struct wokeby_t {42 char name[TASK_COMM_LEN];43 u32 ret;44};45 46struct {47 __uint(type, BPF_MAP_TYPE_HASH);48 __type(key, u32);49 __type(value, struct wokeby_t);50 __uint(max_entries, MAX_ENTRIES);51} wokeby SEC(".maps");52 53struct {54 __uint(type, BPF_MAP_TYPE_STACK_TRACE);55 __uint(key_size, sizeof(u32));56 __uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));57 __uint(max_entries, MAX_ENTRIES);58} stackmap SEC(".maps");59 60#define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)61 62SEC("kprobe/try_to_wake_up")63int waker(struct pt_regs *ctx)64{65 struct task_struct *p = (void *)PT_REGS_PARM1_CORE(ctx);66 u32 pid = BPF_CORE_READ(p, pid);67 struct wokeby_t woke;68 69 bpf_get_current_comm(&woke.name, sizeof(woke.name));70 woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);71 72 bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);73 return 0;74}75 76static inline int update_counts(void *ctx, u32 pid, u64 delta)77{78 struct wokeby_t *woke;79 u64 zero = 0, *val;80 struct key_t key;81 82 __builtin_memset(&key.waker, 0, sizeof(key.waker));83 bpf_get_current_comm(&key.target, sizeof(key.target));84 key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);85 key.wret = 0;86 87 woke = bpf_map_lookup_elem(&wokeby, &pid);88 if (woke) {89 key.wret = woke->ret;90 __builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));91 bpf_map_delete_elem(&wokeby, &pid);92 }93 94 val = bpf_map_lookup_elem(&counts, &key);95 if (!val) {96 bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);97 val = bpf_map_lookup_elem(&counts, &key);98 if (!val)99 return 0;100 }101 (*val) += delta;102 return 0;103}104 105#if 1106/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */107SEC("tracepoint/sched/sched_switch")108int oncpu(struct trace_event_raw_sched_switch *ctx)109{110 /* record previous thread sleep time */111 u32 pid = ctx->prev_pid;112#else113SEC("kprobe.multi/finish_task_switch*")114int oncpu(struct pt_regs *ctx)115{116 struct task_struct *p = (void *)PT_REGS_PARM1_CORE(ctx);117 /* record previous thread sleep time */118 u32 pid = BPF_CORE_READ(p, pid);119#endif120 u64 delta, ts, *tsp;121 122 ts = bpf_ktime_get_ns();123 bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);124 125 /* calculate current thread's delta time */126 pid = bpf_get_current_pid_tgid();127 tsp = bpf_map_lookup_elem(&start, &pid);128 if (!tsp)129 /* missed start or filtered */130 return 0;131 132 delta = bpf_ktime_get_ns() - *tsp;133 bpf_map_delete_elem(&start, &pid);134 delta = delta / 1000;135 if (delta < MINBLOCK_US)136 return 0;137 138 return update_counts(ctx, pid, delta);139}140char _license[] SEC("license") = "GPL";141u32 _version SEC("version") = LINUX_VERSION_CODE;142