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 11:08:45 -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 Wed, May 27, 2020 at 11:07:53AM -0300, Arnaldo Carvalho de Melo escreveu:
> 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,

This:

diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
index a9a056d68416..c5d30834a64c 100644
--- a/tools/perf/jvmti/libjvmti.c
+++ b/tools/perf/jvmti/libjvmti.c
@@ -97,8 +97,8 @@ 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) {
+				} else if (ret == JVMTI_ERROR_ABSENT_INFORMATION ||
+					   ret == JVMTI_ERROR_NATIVE_METHOD) {
 					/* No debug information for this method */
 				} else {
 					print_error(jvmti, "GetLineNumberTable", ret);