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