diff --git a/tools/perf/Documentation/intel-pt.txt b/tools/perf/Documentation/intel-pt.txt
index c94c9de3173ee187f87be72c0ffa128885115c89..886612b50961f0d2bdc6ef3fe154e73a32e3ac6b 100644
--- a/tools/perf/Documentation/intel-pt.txt
+++ b/tools/perf/Documentation/intel-pt.txt
@@ -707,6 +707,11 @@ on the sample is *not* adjusted and reflects the last known value of TSC.
 
 For Intel PT, the default period is 100us.
 
+Setting it to a zero period means "as often as possible".
+
+In the case of Intel PT that is the same as a period of 1 and a unit of
+'instructions' (i.e. --itrace=i1i).
+
 Also the call chain size (default 16, max. 1024) for instructions or
 transactions events can be specified. e.g.
 
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index a980e7c50ee078c47f6579e454572c67616bdc0d..c4993b2e6c50e33909c6f262b0c21d8cce2a830f 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -950,6 +950,7 @@ int itrace_parse_synth_opts(const struct option *opt, const char *str,
 	const char *p;
 	char *endptr;
 	bool period_type_set = false;
+	bool period_set = false;
 
 	synth_opts->set = true;
 
@@ -971,6 +972,7 @@ int itrace_parse_synth_opts(const struct option *opt, const char *str,
 				p += 1;
 			if (isdigit(*p)) {
 				synth_opts->period = strtoull(p, &endptr, 10);
+				period_set = true;
 				p = endptr;
 				while (*p == ' ' || *p == ',')
 					p += 1;
@@ -1053,7 +1055,7 @@ int itrace_parse_synth_opts(const struct option *opt, const char *str,
 		if (!period_type_set)
 			synth_opts->period_type =
 					PERF_ITRACE_DEFAULT_PERIOD_TYPE;
-		if (!synth_opts->period)
+		if (!period_set)
 			synth_opts->period = PERF_ITRACE_DEFAULT_PERIOD;
 	}
 
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 38942e1eac8f53678948d8ed16bea8b7844fb824..c8bb5ca6a1570052320741af793f0b558e66a422 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -720,7 +720,7 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
 
 		if (!params.period) {
 			params.period_type = INTEL_PT_PERIOD_INSTRUCTIONS;
-			params.period = 1000;
+			params.period = 1;
 		}
 	}