linux_dsm_epyc7002/tools/bpf/runqslower/runqslower.bpf.c
Andrii Nakryiko 37ccc12bbc tools/runqslower: Add BPF_F_CURRENT_CPU for running selftest on older kernels
Libbpf compiles and runs subset of selftests on each PR in its Github mirror
repository. To allow still building up-to-date selftests against outdated
kernel images, add back BPF_F_CURRENT_CPU definitions back.

N.B. BCC's runqslower version ([0]) doesn't need BPF_F_CURRENT_CPU due to use of
locally checked in vmlinux.h, generated against kernel with 1aae4bdd78 ("bpf:
Switch BPF UAPI #define constants used from BPF program side to enums")
applied.

  [0] https://github.com/iovisor/bcc/pull/2809

Fixes: 367d82f17e (" tools/runqslower: Drop copy/pasted BPF_F_CURRENT_CPU definiton")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200311043010.530620-1-andriin@fb.com
2020-03-11 15:17:39 +01:00

99 lines
2.2 KiB
C

// 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_HASH);
__uint(max_entries, 10240);
__type(key, u32);
__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(u32 tgid, u32 pid)
{
u64 ts;
if (!pid || (targ_pid && targ_pid != pid))
return 0;
ts = bpf_ktime_get_ns();
bpf_map_update_elem(&start, &pid, &ts, 0);
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->tgid, p->pid);
}
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->tgid, p->pid);
}
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->tgid, prev->pid);
pid = next->pid;
/* fetch timestamp and calculate delta */
tsp = bpf_map_lookup_elem(&start, &pid);
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_map_delete_elem(&start, &pid);
return 0;
}
char LICENSE[] SEC("license") = "GPL";