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

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Date:   Wed, 27 May 2020 11:07:53 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Nick Gasson <nick.gasson@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] perf jvmti: Do not report error when missing debug
 information

Em Mon, Apr 27, 2020 at 02:15:15PM +0800, Nick Gasson escreveu:
> 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>
> ---
>  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) {

Please add the || operator at the end of the line next time, I'm fixing
this up this time,

Applied,

- Arnaldo

> +					/* 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
> 

-- 

- Arnaldo