Re: [PATCH] perf tool: Fix output unexpected messages in quiet mode

[Yang Jihong]

Hello,

On 2022/12/19 18:28, Adrian Hunter wrote:
> On 19/12/22 11:28, Yang Jihong wrote:
> > Hello,
> >
> > On 2022/12/19 14:59, Adrian Hunter wrote:
> > > On 19/12/22 04:49, Yang Jihong wrote:
> > > > When perf uses quiet mode, perf_quiet_option sets debug_peo_args to -1,
> > >
> > > Seems like redirect_to_stderr has similar issue?
> > The redirect_to_stderr is used only in the veprintf function:
> >
> >    int veprintf(int level, int var, const char *fmt, va_list args)
> >    {
> >            int ret = 0;
> >
> >            if (var >= level) {
> >                    if (use_browser >= 1 && redirect_to_stderr <= 0) {
> >                            ui_helpline__vshow(fmt, args);
> >                    } else {
> >                            ret = fprintf_time(debug_file);
> >                            ret += vfprintf(debug_file, fmt, args);
> >                    }
> >            }
> >
> >            return ret;
> >    }
> >
> > If use quiet mode, verbose sets to -1. (also assigned in the perf_quiet_option function)
> > Because "var >= level" is false, veprintf function returns directly, which avoids this problem.
> >
> > However, there are cases where:
> >    # perf --debug stderr=-1 report -vvv 2>/tmp/debug
> >
> > If stderr is -1, should we redirect pr_debug in this case?
>
> tools/perf/Documentation/perf.txt says debug variables are in value
> range (0, 10), so -1 is invalid anyway.
Okay, I see.
> > Because I'm not sure if this is a problem,
> > if redirect_to_stderr needs to be fixed as well,
> > let me know and I'll submit a patch to fix it.
>
> perf_quiet_option() sets redirect_to_stderr = -1 with the intention
> that it turns it off, but it doesn't, although it gets turned of by
> verbose = -1. Perhaps set redirect_to_stderr = 0 in perf_quiet_option() ?
I think it's better to fix redirect_to_stderr and debug_peo_args in the 
same way (because they're similar):

Solution A:
  diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
  index 65e6c22f38e4..908b26e579e5 100644
  --- a/tools/perf/util/debug.c
  +++ b/tools/perf/util/debug.c
  @@ -68,7 +68,7 @@ int veprintf(int level, int var, const char *fmt, 
va_list args)
          int ret = 0;

          if (var >= level) {
  -               if (use_browser >= 1 && !redirect_to_stderr) {
  +               if (use_browser >= 1 && redirect_to_stderr <= 0) {
                          ui_helpline__vshow(fmt, args);
                  } else {
                          ret = fprintf_time(debug_file);
  diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
  index f99468a7f681..f6ab84c93ec0 100644
  --- a/tools/perf/util/debug.h
  +++ b/tools/perf/util/debug.h
  @@ -41,7 +41,7 @@ extern int debug_data_convert;

   /* Special macro to print perf_event_open arguments/return value. */
   #define pr_debug2_peo(fmt, ...) {                              \
  -       if (debug_peo_args)                                             \
  +       if (debug_peo_args > 0)                                         \
                  pr_debugN(0, pr_fmt(fmt), ##__VA_ARGS__);       \
          else                                                    \
                  pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__);       \
  diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
  index 999dd1700502..45cf144c5d5d 100644
  --- a/tools/perf/util/evsel.c
  +++ b/tools/perf/util/evsel.c
  @@ -1775,7 +1775,7 @@ static int __open_attr__fprintf(FILE *fp, const 
char *name, const char *val,

   static void display_attr(struct perf_event_attr *attr)
   {
  -       if (verbose >= 2 || debug_peo_args) {
  +       if (verbose >= 2 || debug_peo_args > 0) {
                  fprintf(stderr, "%.60s\n", graph_dotted_line);
                  fprintf(stderr, "perf_event_attr:\n");
                  perf_event_attr__fprintf(stderr, attr, 
__open_attr__fprintf, NULL);

or
Solution B:

  diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
  index 908b26e579e5..e3acc213edd1 100644
  --- a/tools/perf/util/debug.c
  +++ b/tools/perf/util/debug.c
  @@ -241,6 +241,9 @@ int perf_quiet_option(void)
                  opt++;
          }

  +       redirect_to_stderr = 0;
  +       debug_peo_args = 0;
  +

> I see we have another problem as well: places that check "if (verbose)"
> instead of "if (verbose > 0)"
Yes,  places that "if (verbose)" also have problems, I'll submit a patch 
to change them to "if (verbose > 0)"

In addition, I found another problem, perf lock/stat/probe does not call 
the perf_quiet_option function when quiet is true.

Thanks,
Yang