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Thu, 20 Aug 2020 08:18:42 -0700 (PDT) Received: from mail.google.com ([141.164.41.4]) by smtp.gmail.com with ESMTPSA id y4sm2783205pgb.16.2020.08.20.08.18.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2020 08:18:41 -0700 (PDT) Date: Thu, 20 Aug 2020 23:18:25 +0800 From: Changbin Du To: Arnaldo Carvalho de Melo Cc: Changbin Du , Jiri Olsa , Peter Zijlstra , Ingo Molnar , Namhyung Kim , Steven Rostedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 02/18] perf ftrace: add option '-F/--funcs' to list available functions Message-ID: <20200820151825.idfidxxbat6e32ur@mail.google.com> References: <20200808023141.14227-1-changbin.du@gmail.com> <20200808023141.14227-3-changbin.du@gmail.com> <20200814113535.GS13995@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200814113535.GS13995@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 14, 2020 at 08:35:35AM -0300, Arnaldo Carvalho de Melo wrote: > Em Sat, Aug 08, 2020 at 10:31:25AM +0800, Changbin Du escreveu: > > This adds an option '-F/--funcs' to list all available functions to trace, > > which is read from tracing file 'available_filter_functions'. > > > > $ sudo ./perf ftrace -F | head > > trace_initcall_finish_cb > > initcall_blacklisted > > do_one_initcall > > do_one_initcall > > trace_initcall_start_cb > > run_init_process > > try_to_run_init_process > > match_dev_by_label > > match_dev_by_uuid > > rootfs_init_fs_context > > > > Signed-off-by: Changbin Du > > > > --- > > v3: fix return value issue. > > v2: option name '-l/--list-functions' -> '-F/--funcs' > > --- > > tools/perf/Documentation/perf-ftrace.txt | 4 +++ > > tools/perf/builtin-ftrace.c | 46 ++++++++++++++++++++++++ > > 2 files changed, 50 insertions(+) > > > > diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt > > index 821d4d334a09..4f5628445a63 100644 > > --- a/tools/perf/Documentation/perf-ftrace.txt > > +++ b/tools/perf/Documentation/perf-ftrace.txt > > @@ -31,6 +31,10 @@ OPTIONS > > --verbose=:: > > Verbosity level. > > > > +-F:: > > +--funcs:: > > + List all available functions to trace. > > + > > -p:: > > --pid=:: > > Trace on existing process id (comma separated list). > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > > index 048a11192b59..1ebf71ecc1a8 100644 > > --- a/tools/perf/builtin-ftrace.c > > +++ b/tools/perf/builtin-ftrace.c > > @@ -33,6 +33,7 @@ struct perf_ftrace { > > struct evlist *evlist; > > struct target target; > > const char *tracer; > > + bool list_avail_functions; > > struct list_head filters; > > struct list_head notrace; > > struct list_head graph_funcs; > > @@ -128,6 +129,46 @@ static int append_tracing_file(const char *name, const char *val) > > return __write_tracing_file(name, val, true); > > } > > > > +static int read_tracing_file_to_stdout(const char *name) > > +{ > > + char buf[4096]; > > + char *file; > > + int fd; > > + int ret = -1; > > + > > + file = get_tracing_file(name); > > + if (!file) { > > + pr_debug("cannot get tracing file: %s\n", name); > > + return -1; > > + } > > + > > + fd = open(file, O_RDONLY); > > + if (fd < 0) { > > + pr_debug("cannot open tracing file: %s: %s\n", > > + name, str_error_r(errno, buf, sizeof(buf))); > > + goto out; > > + } > > + > > + /* read contents to stdout */ > > + while (true) { > > + int n = read(fd, buf, sizeof(buf)); > > + if (n == 0) > > + break; > > + else if (n < 0) > > + goto out_close; > > + > > + if (fwrite(buf, n, 1, stdout) != 1) > > + goto out_close; > > + } > > + ret = 0; > > + > > +out_close: > > + close(fd); > > +out: > > + put_tracing_file(file); > > + return ret; > > +} > > + > > static int reset_tracing_cpu(void); > > static void reset_tracing_filters(void); > > > > @@ -302,6 +343,9 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > > signal(SIGCHLD, sig_handler); > > signal(SIGPIPE, sig_handler); > > > > + if (ftrace->list_avail_functions) > > + return read_tracing_file_to_stdout("available_filter_functions"); > > + > > if (reset_tracing_files(ftrace) < 0) { > > pr_err("failed to reset ftrace\n"); > > goto out; > > @@ -487,6 +531,8 @@ int cmd_ftrace(int argc, const char **argv) > > const struct option ftrace_options[] = { > > OPT_STRING('t', "tracer", &ftrace.tracer, "tracer", > > "tracer to use: function_graph(default) or function"), > > + OPT_BOOLEAN('F', "funcs", &ftrace.list_avail_functions, > > + "Show available functions to filter"), > > A boolean? I guess this can be a first step, but why not do it like > 'perf probe' and accept a patterna? Allows for less typing: > > # perf probe -h -F > > -F, --funcs <[FILTER]> > Show potential probe-able functions. > > [root@quaco ~]# > > # perf probe -F '*btf_parse*' > btf_parse_hdr > btf_parse_str_sec > btf_parse_vmlinux > # > # perf ftrace -F | grep btf_parse > btf_parse_str_sec > btf_parse_hdr > btf_parse_vmlinux > # > > I'm applying this to make progress, but please consider sending a patch > to make this behave in the same way as 'perf probe'. > No problem, I'll try to provide similar behaviour for this. Thanks. > - Arnaldo > > > > OPT_STRING('p', "pid", &ftrace.target.pid, "pid", > > "trace on existing process id"), > > OPT_INCR('v', "verbose", &verbose, > > -- > > 2.25.1 > > > > -- > > - Arnaldo -- Cheers, Changbin Du