Linux Perf
5sec.c
Go to the documentation of this file.
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  Description:
4 
5  . Disable strace like syscall tracing (--no-syscalls), or try tracing
6  just some (-e *sleep).
7 
8  . Attach a filter function to a kernel function, returning when it should
9  be considered, i.e. appear on the output.
10 
11  . Run it system wide, so that any sleep of >= 5 seconds and < than 6
12  seconds gets caught.
13 
14  . Ask for callgraphs using DWARF info, so that userspace can be unwound
15 
16  . While this is running, run something like "sleep 5s".
17 
18  . If we decide to add tv_nsec as well, then it becomes:
19 
20  int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)
21 
22  I.e. add where it comes from (rqtp->tv_nsec) and where it will be
23  accessible in the function body (nsec)
24 
25  # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/
26  0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5
27  hrtimer_nanosleep ([kernel.kallsyms])
28  __x64_sys_nanosleep ([kernel.kallsyms])
29  do_syscall_64 ([kernel.kallsyms])
30  entry_SYSCALL_64 ([kernel.kallsyms])
31  __GI___nanosleep (/usr/lib64/libc-2.26.so)
32  rpl_nanosleep (/usr/bin/sleep)
33  xnanosleep (/usr/bin/sleep)
34  main (/usr/bin/sleep)
35  __libc_start_main (/usr/lib64/libc-2.26.so)
36  _start (/usr/bin/sleep)
37  ^C#
38 
39  Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com>
40 */
41 
42 #include <bpf.h>
43 
44 int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec)
45 {
46  return sec == 5;
47 }
48 
49 license(GPL);
int int err
Definition: 5sec.c:44
int int long sec
Definition: 5sec.c:45
license(GPL)
int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx