linux-kernel - Re: [PATCH 2/3] perf jvmti: Do not report error when missing debug information

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Date:   Thu, 14 May 2020 15:08:39 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Nick Gasson <nick.gasson@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] perf jvmti: Do not report error when missing debug information

On Sun, Apr 26, 2020 at 11:16 PM Nick Gasson <nick.gasson@....com> wrote:
>
> If the Java sources are compiled with -g:none to disable debug
> information the perf JVMTI plugin reports a lot of errors like:
>
>   java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
>   java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
>   java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
>   java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
>   java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
>
> Instead if GetLineNumberTable returns JVMTI_ERROR_ABSENT_INFORMATION
> simply skip emitting line number information for that method. Unlike the
> previous patch these errors don't affect the jitdump generation, they
> just generate a lot of noise.
>
> Similarly for native methods which also don't have line tables.
>
> Signed-off-by: Nick Gasson <nick.gasson@....com>

Reviewed-by: Ian Rogers <irogers@...gle.com>
Tested-by: Ian Rogers <irogers@...gle.com>

Thanks!
Ian

> ---
>  tools/perf/jvmti/libjvmti.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
> index 50ef524b5cd4..a9a056d68416 100644
> --- a/tools/perf/jvmti/libjvmti.c
> +++ b/tools/perf/jvmti/libjvmti.c
> @@ -41,7 +41,11 @@ do_get_line_numbers(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
>         jvmtiError ret;
>
>         ret = (*jvmti)->GetLineNumberTable(jvmti, m, &nr_lines, &loc_tab);
> -       if (ret != JVMTI_ERROR_NONE) {
> +       if (ret == JVMTI_ERROR_ABSENT_INFORMATION || ret == JVMTI_ERROR_NATIVE_METHOD) {
> +               /* No debug information for this method */
> +               *nr = 0;
> +               return JVMTI_ERROR_NONE;
> +       } else if (ret != JVMTI_ERROR_NONE) {
>                 print_error(jvmti, "GetLineNumberTable", ret);
>                 return ret;
>         }
> @@ -93,6 +97,9 @@ get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **
>                                         /* free what was allocated for nothing */
>                                         (*jvmti)->Deallocate(jvmti, (unsigned char *)lne);
>                                         nr_total += (int)nr;
> +                               } else if (ret == JVMTI_ERROR_ABSENT_INFORMATION
> +                                          || ret == JVMTI_ERROR_NATIVE_METHOD) {
> +                                       /* No debug information for this method */
>                                 } else {
>                                         print_error(jvmti, "GetLineNumberTable", ret);
>                                 }
> @@ -262,7 +269,9 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
>         if (has_line_numbers && map && map_length) {
>                 ret = get_line_numbers(jvmti, compile_info, &line_tab, &nr_lines);
>                 if (ret != JVMTI_ERROR_NONE) {
> -                       warnx("jvmti: cannot get line table for method");
> +                       if (ret != JVMTI_ERROR_NOT_FOUND) {
> +                               warnx("jvmti: cannot get line table for method");
> +                       }
>                         nr_lines = 0;
>                 } else if (nr_lines > 0) {
>                         line_file_names = malloc(sizeof(char*) * nr_lines);
> --
> 2.26.1
>