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/* Copyright (c) 2016 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include "vmlinux.h"
#include <linux/version.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>
#ifndef PERF_MAX_STACK_DEPTH
#define PERF_MAX_STACK_DEPTH 127
#endif
#define MINBLOCK_US 1
#define MAX_ENTRIES 10000
struct key_t {
char waker[TASK_COMM_LEN];
char target[TASK_COMM_LEN];
u32 wret;
u32 tret;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, struct key_t);
__type(value, u64);
__uint(max_entries, MAX_ENTRIES);
} counts SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, u32);
__type(value, u64);
__uint(max_entries, MAX_ENTRIES);
} start SEC(".maps");
struct wokeby_t {
char name[TASK_COMM_LEN];
u32 ret;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, u32);
__type(value, struct wokeby_t);
__uint(max_entries, MAX_ENTRIES);
} wokeby SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_STACK_TRACE);
__uint(key_size, sizeof(u32));
__uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));
__uint(max_entries, MAX_ENTRIES);
} stackmap SEC(".maps");
#define STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
SEC("kprobe/try_to_wake_up")
int waker(struct pt_regs *ctx)
{
struct task_struct *p = (void *)PT_REGS_PARM1_CORE(ctx);
u32 pid = BPF_CORE_READ(p, pid);
struct wokeby_t woke;
bpf_get_current_comm(&woke.name, sizeof(woke.name));
woke.ret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
bpf_map_update_elem(&wokeby, &pid, &woke, BPF_ANY);
return 0;
}
static inline int update_counts(void *ctx, u32 pid, u64 delta)
{
struct wokeby_t *woke;
u64 zero = 0, *val;
struct key_t key;
__builtin_memset(&key.waker, 0, sizeof(key.waker));
bpf_get_current_comm(&key.target, sizeof(key.target));
key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);
key.wret = 0;
woke = bpf_map_lookup_elem(&wokeby, &pid);
if (woke) {
key.wret = woke->ret;
__builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));
bpf_map_delete_elem(&wokeby, &pid);
}
val = bpf_map_lookup_elem(&counts, &key);
if (!val) {
bpf_map_update_elem(&counts, &key, &zero, BPF_NOEXIST);
val = bpf_map_lookup_elem(&counts, &key);
if (!val)
return 0;
}
(*val) += delta;
return 0;
}
#if 1
/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
SEC("tracepoint/sched/sched_switch")
int oncpu(struct trace_event_raw_sched_switch *ctx)
{
/* record previous thread sleep time */
u32 pid = ctx->prev_pid;
#else
SEC("kprobe.multi/finish_task_switch*")
int oncpu(struct pt_regs *ctx)
{
struct task_struct *p = (void *)PT_REGS_PARM1_CORE(ctx);
/* record previous thread sleep time */
u32 pid = BPF_CORE_READ(p, pid);
#endif
u64 delta, ts, *tsp;
ts = bpf_ktime_get_ns();
bpf_map_update_elem(&start, &pid, &ts, BPF_ANY);
/* calculate current thread's delta time */
pid = bpf_get_current_pid_tgid();
tsp = bpf_map_lookup_elem(&start, &pid);
if (!tsp)
/* missed start or filtered */
return 0;
delta = bpf_ktime_get_ns() - *tsp;
bpf_map_delete_elem(&start, &pid);
delta = delta / 1000;
if (delta < MINBLOCK_US)
return 0;
return update_counts(ctx, pid, delta);
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
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