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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include "runqslower.h"
#define TASK_RUNNING 0
#define BPF_F_CURRENT_CPU 0xffffffffULL
const volatile __u64 min_us = 0;
const volatile pid_t targ_pid = 0;
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, u64);
} start SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(key_size, sizeof(u32));
__uint(value_size, sizeof(u32));
} events SEC(".maps");
/* record enqueue timestamp */
__always_inline
static int trace_enqueue(struct task_struct *t)
{
u32 pid = t->pid;
u64 *ptr;
if (!pid || (targ_pid && targ_pid != pid))
return 0;
ptr = bpf_task_storage_get(&start, t, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!ptr)
return 0;
*ptr = bpf_ktime_get_ns();
return 0;
}
SEC("tp_btf/sched_wakeup")
int handle__sched_wakeup(u64 *ctx)
{
/* TP_PROTO(struct task_struct *p) */
struct task_struct *p = (void *)ctx[0];
return trace_enqueue(p);
}
SEC("tp_btf/sched_wakeup_new")
int handle__sched_wakeup_new(u64 *ctx)
{
/* TP_PROTO(struct task_struct *p) */
struct task_struct *p = (void *)ctx[0];
return trace_enqueue(p);
}
SEC("tp_btf/sched_switch")
int handle__sched_switch(u64 *ctx)
{
/* TP_PROTO(bool preempt, struct task_struct *prev,
* struct task_struct *next)
*/
struct task_struct *prev = (struct task_struct *)ctx[1];
struct task_struct *next = (struct task_struct *)ctx[2];
struct event event = {};
u64 *tsp, delta_us;
long state;
u32 pid;
/* ivcsw: treat like an enqueue event and store timestamp */
if (prev->__state == TASK_RUNNING)
trace_enqueue(prev);
pid = next->pid;
/* For pid mismatch, save a bpf_task_storage_get */
if (!pid || (targ_pid && targ_pid != pid))
return 0;
/* fetch timestamp and calculate delta */
tsp = bpf_task_storage_get(&start, next, 0, 0);
if (!tsp)
return 0; /* missed enqueue */
delta_us = (bpf_ktime_get_ns() - *tsp) / 1000;
if (min_us && delta_us <= min_us)
return 0;
event.pid = pid;
event.delta_us = delta_us;
bpf_get_current_comm(&event.task, sizeof(event.task));
/* output */
bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
&event, sizeof(event));
bpf_task_storage_delete(&start, next);
return 0;
}
char LICENSE[] SEC("license") = "GPL";
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