perf annotate: Add --percent-limit option

Like in 'perf report' and 'perf top', Add this option to limit the
number of functions it displays based on the overhead value in percent.

This affects only stdio and stdio2 output modes. Without this, it
shows very long disassembly lines for every function in the data
file. If users don't want this behavior, they can set a value in
percent to suppress that.

Signed-off-by: Namhyung Kim <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-annotate.txt

···
 	The period/hits keywords set the base the percentage is computed
 	on - the samples period or the number of samples (hits).
 
+--percent-limit::
+	Do not show functions which have an overhead under that percent on
+	stdio or stdio2 (Default: 0).  Note that this is about selection of
+	functions to display, not about lines within the function.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-report[1]

tools/perf/builtin-annotate.c

···
 	bool	   skip_missing;
 	bool	   has_br_stack;
 	bool	   group_set;
+	float	   min_percent;
 	const char *sym_hist_filter;
 	const char *cpu_list;
 	DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
···
 		    (strcmp(he->ms.sym->name, ann->sym_hist_filter) != 0))
 			goto find_next;
 
+		if (ann->min_percent) {
+			float percent = 0;
+			u64 total = hists__total_period(hists);
+
+			if (total)
+				percent = 100.0 * he->stat.period / total;
+
+			if (percent < ann->min_percent)
+				goto find_next;
+		}
+
 		notes = symbol__annotation(he->ms.sym);
 		if (notes->src == NULL) {
 find_next:
···
 	return ret;
 }
 
+static int parse_percent_limit(const struct option *opt, const char *str,
+			       int unset __maybe_unused)
+{
+	struct perf_annotate *ann = opt->value;
+	double pcnt = strtof(str, NULL);
+
+	ann->min_percent = pcnt;
+	return 0;
+}
+
 static const char * const annotate_usage[] = {
 	"perf annotate [<options>]",
 	NULL
···
 	OPT_CALLBACK(0, "percent-type", &annotate.opts, "local-period",
 		     "Set percent type local/global-period/hits",
 		     annotate_parse_percent_type),
+	OPT_CALLBACK(0, "percent-limit", &annotate, "percent",
+		     "Don't show entries under that percent", parse_percent_limit),
 	OPT_CALLBACK_OPTARG(0, "itrace", &itrace_synth_opts, NULL, "opts",
 			    "Instruction Tracing options\n" ITRACE_HELP,
 			    itrace_parse_synth_opts),