Re: [PATCH V3 15/17] perf top: Add option to enable the LBR stitching approach

[Liang, Kan]

On 3/18/2020 8:14 AM, Jiri Olsa wrote:
> On Fri, Mar 13, 2020 at 11:33:17AM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
>
> SNIP
>
> >   #include "util/top.h"
> > @@ -766,6 +767,9 @@ static void perf_event__process_sample(struct perf_tool *tool,
> >   	if (machine__resolve(machine, &al, sample) < 0)
> >   		return;
> >   
> > +	if (top->stitch_lbr)
> > +		al.thread->lbr_stitch_enable = true;
> > +
> >   	if (!machine->kptr_restrict_warned &&
> >   	    symbol_conf.kptr_restrict &&
> >   	    al.cpumode == PERF_RECORD_MISC_KERNEL) {
> > @@ -1543,6 +1547,8 @@ int cmd_top(int argc, const char **argv)
> >   			"number of thread to run event synthesize"),
> >   	OPT_BOOLEAN(0, "namespaces", &opts->record_namespaces,
> >   		    "Record namespaces events"),
> > +	OPT_BOOLEAN(0, "stitch-lbr", &top.stitch_lbr,
> > +		    "Enable LBR callgraph stitching approach"),
> >   	OPTS_EVSWITCH(&top.evswitch),
> >   	OPT_END()
> >   	};
> > @@ -1612,6 +1618,11 @@ int cmd_top(int argc, const char **argv)
> >   		}
> >   	}
> >   
> > +	if (top.stitch_lbr && !(callchain_param.record_mode == CALLCHAIN_LBR)) {
> > +		pr_err("Error: --stitch-lbr must be used with --call-graph lbr\n");
> > +		goto out_delete_evlist;
> > +	}
>
> why is this check not added for script/report/c2c..?

You are right. We should add a check for other tools as well.
I will print a warning as below for other tools in V3.

diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index c798763f62db..0d544c4fb4be 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -2605,6 +2605,12 @@ static int setup_callchain(struct evlist *evlist)
 		}
 	}

+	if (c2c.stitch_lbr && (mode != CALLCHAIN_LBR)) {
+		ui__warning("Can't find LBR callchain. Switch off --stitch-lbr.\n"
+			    "Please apply --call-graph lbr when recording.\n");
+		c2c.stitch_lbr = false;
+	}
+
 	callchain_param.record_mode = mode;
 	callchain_param.min_percent = 0;
 	return 0;
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index e41cedb9256c..3bdbd3649be7 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -411,6 +411,12 @@ static int report__setup_sample_type(struct report 
*rep)
 			callchain_param.record_mode = CALLCHAIN_FP;
 	}

+	if (rep->stitch_lbr && (callchain_param.record_mode != CALLCHAIN_LBR)) {
+		ui__warning("Can't find LBR callchain. Switch off --stitch-lbr.\n"
+			    "Please apply --call-graph lbr when recording.\n");
+		rep->stitch_lbr = false;
+	}
+
 	/* ??? handle more cases than just ANY? */
 	if (!(perf_evlist__combined_branch_type(session->evlist) &
 				PERF_SAMPLE_BRANCH_ANY))
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index f8f50bf95e40..e0ec4a0e7b35 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -3299,6 +3299,12 @@ static void script__setup_sample_type(struct 
perf_script *script)
 		else
 			callchain_param.record_mode = CALLCHAIN_FP;
 	}
+
+	if (script->stitch_lbr && (callchain_param.record_mode != 
CALLCHAIN_LBR)) {
+		pr_warning("Can't find LBR callchain. Switch off --stitch-lbr.\n"
+			   "Please apply --call-graph lbr when recording.\n");
+		script->stitch_lbr = false;
+	}
 }

 static int process_stat_round_event(struct perf_session *session,

Thanks,
Kan