@@ -602,11 +602,27 @@ static void check_tsx_cycles(void)
report_prefix_pop();
}
+static void warm_up(void)
+{
+ int i = 8;
+
+ /*
+ * Since cycles event is always run as the first event, there would be
+ * a warm-up state to warm up the cache, it leads to the measured cycles
+ * value may exceed the pre-defined cycles upper boundary and cause
+ * false positive. To avoid this, introduce an warm-up state before
+ * the real verification.
+ */
+ while (i--)
+ loop();
+}
+
static void check_counters(void)
{
if (is_fep_available())
check_emulated_instr();
+ warm_up();
check_gp_counters();
check_fixed_counters();
check_rdpmc();
When running pmu test on SPR, sometimes the following failure is reported. PMU version: 2 GP counters: 8 GP counter width: 48 Mask length: 8 Fixed counters: 3 Fixed counter width: 48 1000000 <= 55109398 <= 50000000 FAIL: Intel: core cycles-0 1000000 <= 18279571 <= 50000000 PASS: Intel: core cycles-1 1000000 <= 12238092 <= 50000000 PASS: Intel: core cycles-2 1000000 <= 7981727 <= 50000000 PASS: Intel: core cycles-3 1000000 <= 6984711 <= 50000000 PASS: Intel: core cycles-4 1000000 <= 6773673 <= 50000000 PASS: Intel: core cycles-5 1000000 <= 6697842 <= 50000000 PASS: Intel: core cycles-6 1000000 <= 6747947 <= 50000000 PASS: Intel: core cycles-7 The count of the "core cycles" on first counter would exceed the upper boundary and leads to a failure, and then the "core cycles" count would drop gradually and reach a stable state. That looks reasonable. The "core cycles" event is defined as the 1st event in xxx_gp_events[] array and it is always verified at first. when the program loop() is executed at the first time it needs to warm up the pipeline and cache, such as it has to wait for cache is filled. All these warm-up work leads to a quite large core cycles count which may exceeds the verification range. To avoid the false positive of cycles event caused by warm-up, explicitly introduce a warm-up state before really starting verification. Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> --- x86/pmu.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)