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Message-ID: <tip-2nmxth2l2h09f9gy85lyexcq@git.kernel.org>
Date: Wed, 16 May 2018 11:03:29 -0700
From: tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: tglx@...utronix.de, dsahern@...il.com, wangnan0@...wei.com,
acme@...hat.com, namhyung@...nel.org, linux-kernel@...r.kernel.org,
jolsa@...nel.org, mingo@...nel.org, hpa@...or.com,
adrian.hunter@...el.com
Subject: [tip:perf/core] perf bpf: Add kprobe example to catch 5s naps
Commit-ID: 7542b767b0469f4a76afa3feae6246d8a3d44e7f
Gitweb: https://git.kernel.org/tip/7542b767b0469f4a76afa3feae6246d8a3d44e7f
Author: Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Fri, 4 May 2018 15:08:01 -0300
Committer: Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Tue, 15 May 2018 14:31:24 -0300
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@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: https://lkml.kernel.org/n/tip-2nmxth2l2h09f9gy85lyexcq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/perf/examples/bpf/5sec.c | 44 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
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@...hat.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;
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