selftests/resctrl: Keep results from first test run

The resctrl selftests drop the results from every first test run
to avoid (per comment) "inaccurate due to monitoring setup transition
phase" data. Previously inaccurate data resulted from workloads needing
some time to "settle" and also the measurements themselves to
account for earlier measurements to measure across needed timeframe.

commit da50de0a92f3 ("selftests/resctrl: Calculate resctrl FS derived mem
bw over sleep(1) only")

ensured that measurements accurately measure just the time frame of
interest. The default "fill_buf" benchmark since separated the buffer
prepare phase from the benchmark run phase reducing the need for the
tests themselves to accommodate the benchmark's "settle" time.

With these enhancements there are no remaining portions needing
to "settle" and the first test run can contribute to measurements.

Signed-off-by: Reinette Chatre <[e-mail]>
Reviewed-by: Ilpo Järvinen <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/resctrl/cmt_test.c

···
 		}
 
 		/* Field 3 is llc occ resc value */
-		if (runs > 0)
-			sum_llc_occu_resc += strtoul(token_array[3], NULL, 0);
+		sum_llc_occu_resc += strtoul(token_array[3], NULL, 0);
 		runs++;
 	}
 	fclose(fp);
 
 	return show_results_info(sum_llc_occu_resc, no_of_bits, span,
-				 MAX_DIFF, MAX_DIFF_PERCENT, runs - 1, true);
+				 MAX_DIFF, MAX_DIFF_PERCENT, runs, true);
 }
 
 static void cmt_test_cleanup(void)

tools/testing/selftests/resctrl/mba_test.c

···
 		int avg_diff_per;
 		float avg_diff;
 
-		/*
-		 * The first run is discarded due to inaccurate value from
-		 * phase transition.
-		 */
-		for (runs = NUM_OF_RUNS * allocation + 1;
+		for (runs = NUM_OF_RUNS * allocation;
 		     runs < NUM_OF_RUNS * allocation + NUM_OF_RUNS ; runs++) {
 			sum_bw_imc += bw_imc[runs];
 			sum_bw_resc += bw_resc[runs];
 		}
 
-		avg_bw_imc = sum_bw_imc / (NUM_OF_RUNS - 1);
-		avg_bw_resc = sum_bw_resc / (NUM_OF_RUNS - 1);
+		avg_bw_imc = sum_bw_imc / NUM_OF_RUNS;
+		avg_bw_resc = sum_bw_resc / NUM_OF_RUNS;
 		if (avg_bw_imc < THROTTLE_THRESHOLD || avg_bw_resc < THROTTLE_THRESHOLD) {
 			ksft_print_msg("Bandwidth below threshold (%d MiB). Dropping results from MBA schemata %u.\n",
 				       THROTTLE_THRESHOLD,

tools/testing/selftests/resctrl/mbm_test.c

···
 	int runs, ret, avg_diff_per;
 	float avg_diff = 0;
 
-	/*
-	 * Discard the first value which is inaccurate due to monitoring setup
-	 * transition phase.
-	 */
-	for (runs = 1; runs < NUM_OF_RUNS ; runs++) {
+	for (runs = 0; runs < NUM_OF_RUNS; runs++) {
 		sum_bw_imc += bw_imc[runs];
 		sum_bw_resc += bw_resc[runs];
 	}
 
-	avg_bw_imc = sum_bw_imc / 4;
-	avg_bw_resc = sum_bw_resc / 4;
+	avg_bw_imc = sum_bw_imc / NUM_OF_RUNS;
+	avg_bw_resc = sum_bw_resc / NUM_OF_RUNS;
 	avg_diff = (float)labs(avg_bw_resc - avg_bw_imc) / avg_bw_imc;
 	avg_diff_per = (int)(avg_diff * 100);