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author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-05-04 15:08:01 -0300 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-05-15 14:31:24 -0300 |
commit | 7542b767b0469f4a76afa3feae6246d8a3d44e7f (patch) | |
tree | bc8050bfecf2a8fd0b14e7293f61298ec042aa06 /tools/perf/examples | |
parent | dd8e4ead6e983acea959d10252688ef1471106fe (diff) | |
download | linux-7542b767b0469f4a76afa3feae6246d8a3d44e7f.tar.bz2 |
perf bpf: Add kprobe example to catch 5s naps
Description:
. Disable strace like syscall tracing (--no-syscalls), or try tracing
just some (-e *sleep).
. Attach a filter function to a kernel function, returning when it should
be considered, i.e. appear on the output:
$ cat tools/perf/examples/bpf/5sec.c
#include <bpf.h>
SEC("func=hrtimer_nanosleep rqtp->tv_sec")
int func(void *ctx, int err, long sec)
{
return sec == 5;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
$
. Run it system wide, so that any sleep of >= 5 seconds and < than 6
seconds gets caught.
. Ask for callgraphs using DWARF info, so that userspace can be unwound
. While this is running, run something like "sleep 5s".
# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/
0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5
hrtimer_nanosleep ([kernel.kallsyms])
__x64_sys_nanosleep ([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
entry_SYSCALL_64 ([kernel.kallsyms])
__GI___nanosleep (/usr/lib64/libc-2.26.so)
rpl_nanosleep (/usr/bin/sleep)
xnanosleep (/usr/bin/sleep)
main (/usr/bin/sleep)
__libc_start_main (/usr/lib64/libc-2.26.so)
_start (/usr/bin/sleep)
^C#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-2nmxth2l2h09f9gy85lyexcq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/examples')
-rw-r--r-- | tools/perf/examples/bpf/5sec.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/tools/perf/examples/bpf/5sec.c b/tools/perf/examples/bpf/5sec.c new file mode 100644 index 000000000000..3d1ed34aec8b --- /dev/null +++ b/tools/perf/examples/bpf/5sec.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + Description: + + . Disable strace like syscall tracing (--no-syscalls), or try tracing + just some (-e *sleep). + + . Attach a filter function to a kernel function, returning when it should + be considered, i.e. appear on the output. + + . Run it system wide, so that any sleep of >= 5 seconds and < than 6 + seconds gets caught. + + . Ask for callgraphs using DWARF info, so that userspace can be unwound + + . While this is running, run something like "sleep 5s". + + # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/ + 0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5 + hrtimer_nanosleep ([kernel.kallsyms]) + __x64_sys_nanosleep ([kernel.kallsyms]) + do_syscall_64 ([kernel.kallsyms]) + entry_SYSCALL_64 ([kernel.kallsyms]) + __GI___nanosleep (/usr/lib64/libc-2.26.so) + rpl_nanosleep (/usr/bin/sleep) + xnanosleep (/usr/bin/sleep) + main (/usr/bin/sleep) + __libc_start_main (/usr/lib64/libc-2.26.so) + _start (/usr/bin/sleep) + ^C# + + Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <acme@redhat.com> +*/ + +#include <bpf.h> + +SEC("func=hrtimer_nanosleep rqtp->tv_sec") +int func(void *ctx, int err, long sec) +{ + return sec == 5; +} + +char _license[] SEC("license") = "GPL"; +int _version SEC("version") = LINUX_VERSION_CODE; |