[PATCH 22/23] perf ftrace: Introduce new 'ftrace' tool

Arnaldo Carvalho de Melo
2017-01-25T13:55:25Z

From: Namhyung Kim <namhyung.kim@lge.com>

The 'perf ftrace' command is a simple wrapper of kernel's ftrace
functionality. It only supports single thread tracing currently and
just reads trace_pipe in text and then write it to stdout.

Committer notes:

Testing it:

# perf ftrace -f function_graph usleep 123456
<SNIP>
2) | SyS_nanosleep() {
2) | _copy_from_user() {
<SNIP>
2) 0.900 us | }
2) 1.354 us | }
2) | hrtimer_nanosleep() {
2) 0.062 us | __hrtimer_init();
2) | do_nanosleep() {
2) | hrtimer_start_range_ns() {
<SNIP>
2) 5.025 us | }
2) | schedule() {
2) 0.125 us | rcu_note_context_switch();
2) 0.057 us | _raw_spin_lock();
2) | deactivate_task() {
2) 0.369 us | update_rq_clock.part.77();
2) | dequeue_task_fair() {
<SNIP>
2) + 22.453 us | }
2) + 23.736 us | }
2) | pick_next_task_fair() {
<SNIP>
2) + 47.167 us | }
2) | pick_next_task_idle() {
<SNIP>
2) 4.462 us | }
------------------------------------------
2) usleep-20387 => <idle>-0
------------------------------------------

2) 0.806 us | switch_mm_irqs_off();
------------------------------------------
2) <idle>-0 => usleep-20387
------------------------------------------

2) 0.151 us | finish_task_switch();
2) @ 123597.2 us | }
2) 0.037 us | _cond_resched();
2) | hrtimer_try_to_cancel() {
2) 0.064 us | hrtimer_active();
2) 0.353 us | }
2) @ 123605.3 us | }
2) @ 123606.2 us | }
2) @ 123608.3 us | } /* SyS_nanosleep */
2) | __do_page_fault() {
<SNIP>

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jeremy Eder <jeder@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>,
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-r1hgmsj4dxny8arn3o9mw512@git.kernel.org
[ Various foward port fixes, add man page ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Build | 1 +
tools/perf/Documentation/perf-ftrace.txt | 36 +++++
tools/perf/builtin-ftrace.c | 242 +++++++++++++++++++++++++++++++
tools/perf/builtin.h | 1 +
tools/perf/command-list.txt | 1 +
tools/perf/perf.c | 1 +
6 files changed, 282 insertions(+)
create mode 100644 tools/perf/Documentation/perf-ftrace.txt
create mode 100644 tools/perf/builtin-ftrace.c

diff --git a/tools/perf/Build b/tools/perf/Build
index 7039ecb89170..9b79f8d7db50 100644
--- a/tools/perf/Build
+++ b/tools/perf/Build
@@ -3,6 +3,7 @@ perf-y += builtin-annotate.o
perf-y += builtin-config.o
perf-y += builtin-diff.o
perf-y += builtin-evlist.o
+perf-y += builtin-ftrace.o
perf-y += builtin-help.o
perf-y += builtin-sched.o
perf-y += builtin-buildid-list.o
diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
new file mode 100644
index 000000000000..2d96de6132a9
--- /dev/null
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -0,0 +1,36 @@
+perf-ftrace(1)
+=============
+
+NAME
+----
+perf-ftrace - simple wrapper for kernel's ftrace functionality
+
+
+SYNOPSIS
+--------
+[verse]
+'perf ftrace' <command>
+
+DESCRIPTION
+-----------
+The 'perf ftrace' command is a simple wrapper of kernel's ftrace
+functionality. It only supports single thread tracing currently and
+just reads trace_pipe in text and then write it to stdout.
+
+The following options apply to perf ftrace.
+
+OPTIONS
+-------
+
+-t::
+--tracer=::
+ Tracer to use: function_graph or function.
+
+-v::
+--verbose=::
+ Verbosity level.
+
+
+SEE ALSO
+--------
+linkperf:perf-record[1], linkperf:perf-trace[1]
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
new file mode 100644
index 000000000000..c320ae25c8e6
--- /dev/null
+++ b/tools/perf/builtin-ftrace.c
@@ -0,0 +1,242 @@
+/*
+ * builtin-ftrace.c
+ *
+ * Copyright (c) 2013 LG Electronics, Namhyung Kim <namhyung@kernel.org>
+ *
+ * Released under the GPL v2.
+ */
+
+#include "builtin.h"
+#include "perf.h"
+
+#include <unistd.h>
+#include <signal.h>
+
+#include "debug.h"
+#include <subcmd/parse-options.h>
+#include "evlist.h"
+#include "target.h"
+#include "thread_map.h"
+
+
+#define DEFAULT_TRACER "function_graph"
+
+struct perf_ftrace {
+ struct perf_evlist *evlist;
+ struct target target;
+ const char *tracer;
+};
+
+static bool done;
+
+static void sig_handler(int sig __maybe_unused)
+{
+ done = true;
+}
+
+/*
+ * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
+ * we asked by setting its exec_error to the function below,
+ * ftrace__workload_exec_failed_signal.
+ *
+ * XXX We need to handle this more appropriately, emitting an error, etc.
+ */
+static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
+ siginfo_t *info __maybe_unused,
+ void *ucontext __maybe_unused)
+{
+ /* workload_exec_errno = info->si_value.sival_int; */
+ done = true;
+}
+
+static int write_tracing_file(const char *name, const char *val)
+{
+ char *file;
+ int fd, ret = -1;
+ ssize_t size = strlen(val);
+
+ file = get_tracing_file(name);
+ if (!file) {
+ pr_debug("cannot get tracing file: %s\n", name);
+ return -1;
+ }
+
+ fd = open(file, O_WRONLY);
+ if (fd < 0) {
+ pr_debug("cannot open tracing file: %s\n", name);
+ goto out;
+ }
+
+ if (write(fd, val, size) == size)
+ ret = 0;
+ else
+ pr_debug("write '%s' to tracing/%s failed\n", val, name);
+
+ close(fd);
+out:
+ put_tracing_file(file);
+ return ret;
+}
+
+static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
+{
+ if (write_tracing_file("tracing_on", "0") < 0)
+ return -1;
+
+ if (write_tracing_file("current_tracer", "nop") < 0)
+ return -1;
+
+ if (write_tracing_file("set_ftrace_pid", " ") < 0)
+ return -1;
+
+ return 0;
+}
+
+static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
+{
+ char *trace_file;
+ int trace_fd;
+ char *trace_pid;
+ char buf[4096];
+ struct pollfd pollfd = {
+ .events = POLLIN,
+ };
+
+ if (geteuid() != 0) {
+ pr_err("ftrace only works for root!\n");
+ return -1;
+ }
+
+ if (argc < 1)
+ return -1;
+
+ signal(SIGINT, sig_handler);
+ signal(SIGUSR1, sig_handler);
+ signal(SIGCHLD, sig_handler);
+
+ reset_tracing_files(ftrace);
+
+ /* reset ftrace buffer */
+ if (write_tracing_file("trace", "0") < 0)
+ goto out;
+
+ if (perf_evlist__prepare_workload(ftrace->evlist, &ftrace->target,
+ argv, false, ftrace__workload_exec_failed_signal) < 0)
+ goto out;
+
+ if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
+ pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
+ goto out;
+ }
+
+ if (asprintf(&trace_pid, "%d", thread_map__pid(ftrace->evlist->threads, 0)) < 0) {
+ pr_err("failed to allocate pid string\n");
+ goto out;
+ }
+
+ if (write_tracing_file("set_ftrace_pid", trace_pid) < 0) {
+ pr_err("failed to set pid: %s\n", trace_pid);
+ goto out_free_pid;
+ }
+
+ trace_file = get_tracing_file("trace_pipe");
+ if (!trace_file) {
+ pr_err("failed to open trace_pipe\n");
+ goto out_free_pid;
+ }
+
+ trace_fd = open(trace_file, O_RDONLY);
+
+ put_tracing_file(trace_file);
+
+ if (trace_fd < 0) {
+ pr_err("failed to open trace_pipe\n");
+ goto out_free_pid;
+ }
+
+ fcntl(trace_fd, F_SETFL, O_NONBLOCK);
+ pollfd.fd = trace_fd;
+
+ if (write_tracing_file("tracing_on", "1") < 0) {
+ pr_err("can't enable tracing\n");
+ goto out_close_fd;
+ }
+
+ perf_evlist__start_workload(ftrace->evlist);
+
+ while (!done) {
+ if (poll(&pollfd, 1, -1) < 0)
+ break;
+
+ if (pollfd.revents & POLLIN) {
+ int n = read(trace_fd, buf, sizeof(buf));
+ if (n < 0)
+ break;
+ if (fwrite(buf, n, 1, stdout) != 1)
+ break;
+ }
+ }
+
+ write_tracing_file("tracing_on", "0");
+
+ /* read remaining buffer contents */
+ while (true) {
+ int n = read(trace_fd, buf, sizeof(buf));
+ if (n <= 0)
+ break;
+ if (fwrite(buf, n, 1, stdout) != 1)
+ break;
+ }
+
+out_close_fd:
+ close(trace_fd);
+out_free_pid:
+ free(trace_pid);
+out:
+ reset_tracing_files(ftrace);
+
+ return done ? 0 : -1;
+}
+
+int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused)
+{
+ int ret;
+ struct perf_ftrace ftrace = {
+ .target = { .uid = UINT_MAX, },
+ };
+ const char * const ftrace_usage[] = {
+ "perf ftrace [<options>] <command>",
+ "perf ftrace [<options>] -- <command> [<options>]",
+ NULL
+ };
+ const struct option ftrace_options[] = {
+ OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
+ "tracer to use: function_graph or function"),
+ OPT_INCR('v', "verbose", &verbose,
+ "be more verbose"),
+ OPT_END()
+ };
+
+ argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
+ PARSE_OPT_STOP_AT_NON_OPTION);
+ if (!argc)
+ usage_with_options(ftrace_usage, ftrace_options);
+
+ ftrace.evlist = perf_evlist__new();
+ if (ftrace.evlist == NULL)
+ return -ENOMEM;
+
+ ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
+ if (ret < 0)
+ goto out_delete_evlist;
+
+ if (ftrace.tracer == NULL)
+ ftrace.tracer = DEFAULT_TRACER;
+
+ ret = __cmd_ftrace(&ftrace, argc, argv);
+
+out_delete_evlist:
+ perf_evlist__delete(ftrace.evlist);
+
+ return ret;
+}
diff --git a/tools/perf/builtin.h b/tools/perf/builtin.h
index b55f5be486a1..036e1e35b1a8 100644
--- a/tools/perf/builtin.h
+++ b/tools/perf/builtin.h
@@ -41,6 +41,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix);
int cmd_inject(int argc, const char **argv, const char *prefix);
int cmd_mem(int argc, const char **argv, const char *prefix);
int cmd_data(int argc, const char **argv, const char *prefix);
+int cmd_ftrace(int argc, const char **argv, const char *prefix);

int find_scripts(char **scripts_array, char **scripts_path_array);
#endif
diff --git a/tools/perf/command-list.txt b/tools/perf/command-list.txt
index fb45613dba9e..ac3efd396a72 100644
--- a/tools/perf/command-list.txt
+++ b/tools/perf/command-list.txt
@@ -11,6 +11,7 @@ perf-data mainporcelain common
perf-diff mainporcelain common
perf-config mainporcelain common
perf-evlist mainporcelain common
+perf-ftrace mainporcelain common
perf-inject mainporcelain common
perf-kallsyms mainporcelain common
perf-kmem mainporcelain common
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index c71000e022d7..6d5479e03e0d 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -71,6 +71,7 @@ static struct cmd_struct commands[] = {
{ "inject", cmd_inject, 0 },
{ "mem", cmd_mem, 0 },
{ "data", cmd_data, 0 },
+ { "ftrace", cmd_ftrace, 0 },
};

struct pager_config {
--
2.9.3