Messages in this thread Patch in this message | | | Date | Tue, 31 Jan 2017 09:46:29 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v2 2/4] perf ftrace: Add ftrace.tracer config option |
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Em Tue, Jan 31, 2017 at 08:38:29PM +0900, Taeung Song escreveu: > Currently perf ftrace command will select 'function_graph' or 'function'. > So add ftrace.tracer config option to select tracer
The above is confusing, I changed it to:
Currently 'perf ftrace' command allows selecting 'function_graph' or 'function', defaulting to 'function_graph'.
Add the ftrace.tracer config option to select the default tracer:
> # cat ~/.perfconfig > [ftrace] > tracer = function > > # perf ftrace usleep 123456 | head -10 > <...>-14450 [002] d... 10089.284231: finish_task_switch <-__schedule > <...>-14450 [002] .... 10089.284232: finish_wait <-pipe_wait > <...>-14450 [002] .... 10089.284232: mutex_lock <-pipe_wait > <...>-14450 [002] .... 10089.284232: _cond_resched <-mutex_lock > > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Namhyung Kim <namhyung@kernel.org> > Signed-off-by: Taeung Song <treeze.taeung@gmail.com> > --- > tools/perf/builtin-ftrace.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > index 414444d..00e228f 100644 > --- a/tools/perf/builtin-ftrace.c > +++ b/tools/perf/builtin-ftrace.c > @@ -17,6 +17,7 @@ > #include "evlist.h" > #include "target.h" > #include "thread_map.h" > +#include "util/config.h" > > > #define DEFAULT_TRACER "function_graph" > @@ -198,6 +199,26 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > return done ? 0 : -1; > } > > +static int perf_ftrace_config(const char *var, const char *value, void *cb) > +{ > + struct perf_ftrace *ftrace = cb; > + > + if (!strcmp(var, "ftrace.tracer")) { > + if (!strcmp(value, "function_graph")) > + ftrace->tracer = DEFAULT_TRACER; > + else if (!strcmp(value, "function")) > + ftrace->tracer = "function"; > + else { > + pr_err("Please select function_graph(default)" > + "or function to use tracer.\n"); > + return -1; > + }
If you use {} in the else case, use it in the other branch, also I simplified it to be:
+ if (!strcmp(var, "ftrace.tracer")) { + if (!strcmp(value, "function_graph") || + !strcmp(value, "function")) + ftrace->tracer = value; + else { + pr_err("Please select function_graph(default)" + "or function to use tracer.\n"); + return -1; + }
As we know item->value will not go away (its a perf_config_item, allocated and kept in that perf_config_set structure).
Also it doesn't make sense comparing against "function_graph" to set it to DEFAULT_TRACER, as if we decide to change the DEFAULT_TRACER this simply breaks.
Also you forgot to test by setting an invalid tracer, I did and noticed that you forgot to add a space between "(default)" and "or ", please be more careful with testing.
Also you are silently ignoring any unknown variable in this section, so if someone has this:
cat ~/.perfconfig
[ftrace]
trace = function
I.e. forgets the 'r', it will keep using the current default, "function_graph" till the user checks the config and adds that missing 'r'...
I haven't changed this because I think this is so common that we should instead have a different error return for those config callbacks that will tell perf_config() to say something like:
"unknown variable %s.%s\n", section_name, variable_name
- Arnaldo
> + return 0; > + } > + > + return 0; > +} > + > int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused) > { > int ret; > @@ -218,6 +239,10 @@ int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused) > OPT_END() > }; > > + 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) > -- > 2.7.4
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