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Date: Wed, 20 May 2020 17:56:21 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Changbin Du <changbin.du@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/19] perf ftrace: select function/function_graph tracer
automatically
Em Sun, May 10, 2020 at 11:06:12PM +0800, Changbin Du escreveu:
> The '-g/-G' options have already implied function_graph tracer should be
> used instead of function tracer. So the extra option '--tracer' can be
> killed.
Well, since it is there, lets not remove it, you can even add a
"Deprecated" message to it and then after some time, remove it.
Also, in this area, -g is used for asking for callchains in other perf
tools, so its a candidate for a change in behaviour, as well with some
deprecation warning for a while, using --call-graph for a while, etc.
I.e. we want it to have a similar set of options as the other perf
tools, so that switching from, say:
# perf trace <options> workload
To:
# perf ftrace <options> workload
Would provide a similar experience, only that the first is limited to
syscalls, the other to kernel functions.
- Arnaldo
> This patch changes the behavior as below:
> - By default, function tracer is used.
> - If '-g' or '-G' option is on, then function_graph tracer is used.
> - The perf configuration item 'ftrace.tracer' is removed.
> - The default filter for -G is to trace all functions.
>
> Here are some examples.
>
> This will start tracing all functions using function tracer:
> $ sudo perf ftrace
>
> This will trace all functions using function graph tracer:
> $ sudo perf ftrace -G
>
> This will trace function vfs_read using function graph tracer:
> $ sudo perf ftrace -G vfs_read
>
> Signed-off-by: Changbin Du <changbin.du@...il.com>
> ---
> tools/perf/Documentation/perf-config.txt | 5 ---
> tools/perf/builtin-ftrace.c | 39 ++++++------------------
> 2 files changed, 9 insertions(+), 35 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
> index f16d8a71d3f5..fad6c48ed76a 100644
> --- a/tools/perf/Documentation/perf-config.txt
> +++ b/tools/perf/Documentation/perf-config.txt
> @@ -612,11 +612,6 @@ trace.*::
> "libbeauty", the default, to use the same argument beautifiers used in the
> strace-like sys_enter+sys_exit lines.
>
> -ftrace.*::
> - ftrace.tracer::
> - Can be used to select the default tracer. Possible values are
> - 'function' and 'function_graph'.
> -
> llvm.*::
> llvm.clang-path::
> Path to clang. If omit, search it from $PATH.
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 5584f8dec25d..57e656c35d28 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -27,7 +27,7 @@
> #include "util/cap.h"
> #include "util/config.h"
>
> -#define DEFAULT_TRACER "function_graph"
> +#define DEFAULT_TRACER "function"
>
> struct perf_ftrace {
> struct evlist *evlist;
> @@ -408,26 +408,6 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> return (done && !workload_exec_errno) ? 0 : -1;
> }
>
> -static int perf_ftrace_config(const char *var, const char *value, void *cb)
> -{
> - struct perf_ftrace *ftrace = cb;
> -
> - if (!strstarts(var, "ftrace."))
> - return 0;
> -
> - if (strcmp(var, "ftrace.tracer"))
> - return -1;
> -
> - if (!strcmp(value, "function_graph") ||
> - !strcmp(value, "function")) {
> - ftrace->tracer = value;
> - return 0;
> - }
> -
> - pr_err("Please select \"function_graph\" (default) or \"function\"\n");
> - return -1;
> -}
> -
> static int parse_filter_func(const struct option *opt, const char *str,
> int unset __maybe_unused)
> {
> @@ -467,8 +447,6 @@ int cmd_ftrace(int argc, const char **argv)
> NULL
> };
> const struct option ftrace_options[] = {
> - OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
> - "tracer to use: function_graph(default) or function"),
> OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
> "trace on existing process id"),
> OPT_INCR('v', "verbose", &verbose,
> @@ -481,10 +459,12 @@ int cmd_ftrace(int argc, const char **argv)
> "trace given functions only", parse_filter_func),
> OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
> "do not trace given functions", parse_filter_func),
> - OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
> - "Set graph filter on given functions", parse_filter_func),
> + OPT_CALLBACK_DEFAULT('G', "graph-funcs", &ftrace.graph_funcs, "func",
> + "Set graph filter on given functions (imply to use function_graph tracer)",
> + parse_filter_func, "*"),
> OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",
> - "Set nograph filter on given functions", parse_filter_func),
> + "Set nograph filter on given functions (imply to use function_graph tracer)",
> + parse_filter_func),
> OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
> "Max depth for function graph tracer"),
> OPT_END()
> @@ -495,15 +475,14 @@ int cmd_ftrace(int argc, const char **argv)
> INIT_LIST_HEAD(&ftrace.graph_funcs);
> INIT_LIST_HEAD(&ftrace.nograph_funcs);
>
> - ret = perf_config(perf_ftrace_config, &ftrace);
> - if (ret < 0)
> - return -1;
> -
> argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
> PARSE_OPT_STOP_AT_NON_OPTION);
> if (!argc && target__none(&ftrace.target))
> ftrace.target.system_wide = true;
>
> + if (!list_empty(&ftrace.graph_funcs) || !list_empty(&ftrace.nograph_funcs))
> + ftrace.tracer = "function_graph";
> +
> ret = target__validate(&ftrace.target);
> if (ret) {
> char errbuf[512];
> --
> 2.25.1
>
--
- Arnaldo
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