MBM unit test starts fill_buf (default built-in benchmark) in a new con_mon group (c1, m1) and records resctrl reported mbm values and iMC (Integrated Memory Controller) values every second. It does this for five seconds (randomly chosen value) in total. It then calculates average of resctrl_mbm values and imc_mbm values and if the difference is greater than 300 MB/sec (randomly chosen value), the test treats it as a failure. MBA unit test is similar to MBM but after every run it changes schemata.
Checking for a difference of 300 MB/sec doesn't look very meaningful when the mbm values are changing over a wide range. For example, below are the values running MBA test on SKL with different allocations
1. With 10% as schemata both iMC and resctrl mbm_values are around 2000 MB/sec 2. With 100% as schemata both iMC and resctrl mbm_values are around 10000 MB/sec
A 300 MB/sec difference between resctrl_mbm and imc_mbm values is acceptable at 100% schemata but it isn't acceptable at 10% schemata because that's a huge difference.
So, fix this by checking for percentage difference instead of absolute difference i.e. check if the difference between resctrl_mbm value and imc_mbm value is within 5% (randomly chosen value) of imc_mbm value. If the difference is greater than 5% of imc_mbm value, treat it is a failure.
Signed-off-by: Fenghua Yu fenghua.yu@intel.com --- tools/testing/selftests/resctrl/mba_test.c | 22 +++++++++++++--------- tools/testing/selftests/resctrl/mbm_test.c | 15 ++++++++------- 2 files changed, 21 insertions(+), 16 deletions(-)
diff --git a/tools/testing/selftests/resctrl/mba_test.c b/tools/testing/selftests/resctrl/mba_test.c index 3a226effe80c..fd66a831062c 100644 --- a/tools/testing/selftests/resctrl/mba_test.c +++ b/tools/testing/selftests/resctrl/mba_test.c @@ -12,7 +12,7 @@
#define RESULT_FILE_NAME "result_mba" #define NUM_OF_RUNS 5 -#define MAX_DIFF 300 +#define MAX_DIFF_PERCENT 5 #define ALLOCATION_MAX 100 #define ALLOCATION_MIN 10 #define ALLOCATION_STEP 10 @@ -62,7 +62,8 @@ static void show_mba_info(unsigned long *bw_imc, unsigned long *bw_resc) allocation++) { unsigned long avg_bw_imc, avg_bw_resc; unsigned long sum_bw_imc = 0, sum_bw_resc = 0; - unsigned long avg_diff; + int avg_diff_per; + float avg_diff;
/* * The first run is discarded due to inaccurate value from @@ -76,16 +77,19 @@ static void show_mba_info(unsigned long *bw_imc, unsigned long *bw_resc)
avg_bw_imc = sum_bw_imc / (NUM_OF_RUNS - 1); avg_bw_resc = sum_bw_resc / (NUM_OF_RUNS - 1); - avg_diff = labs((long)(avg_bw_resc - avg_bw_imc)); + avg_diff = (float)labs(avg_bw_resc - avg_bw_imc) / avg_bw_imc; + avg_diff_per = (int)(avg_diff * 100);
- ksft_print_msg("%s MBA schemata percentage %u smaller than %d %%\n", - avg_diff > MAX_DIFF ? "fail:" : "pass:", - ALLOCATION_MAX - ALLOCATION_STEP * allocation, - MAX_DIFF); - ksft_print_msg("avg_diff: %lu\n", avg_diff); + ksft_print_msg("%s MBA: diff within %d%% for schemata %u\n", + avg_diff_per > MAX_DIFF_PERCENT ? + "fail:" : "pass:", + MAX_DIFF_PERCENT, + ALLOCATION_MAX - ALLOCATION_STEP * allocation); + + ksft_print_msg("avg_diff_per: %d%%\n", avg_diff_per); ksft_print_msg("avg_bw_imc: %lu\n", avg_bw_imc); ksft_print_msg("avg_bw_resc: %lu\n", avg_bw_resc); - if (avg_diff > MAX_DIFF) + if (avg_diff_per > MAX_DIFF_PERCENT) failed = true; }
diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/selftests/resctrl/mbm_test.c index 2b4f26013d84..44a89e0267eb 100644 --- a/tools/testing/selftests/resctrl/mbm_test.c +++ b/tools/testing/selftests/resctrl/mbm_test.c @@ -11,7 +11,7 @@ #include "resctrl.h"
#define RESULT_FILE_NAME "result_mbm" -#define MAX_DIFF 300 +#define MAX_DIFF_PERCENT 5 #define NUM_OF_RUNS 5
static int @@ -19,8 +19,8 @@ show_bw_info(unsigned long *bw_imc, unsigned long *bw_resc, int span) { unsigned long avg_bw_imc = 0, avg_bw_resc = 0; unsigned long sum_bw_imc = 0, sum_bw_resc = 0; - long avg_diff = 0; - int runs, ret; + int runs, ret, avg_diff_per; + float avg_diff = 0;
/* * Discard the first value which is inaccurate due to monitoring setup @@ -33,12 +33,13 @@ show_bw_info(unsigned long *bw_imc, unsigned long *bw_resc, int span)
avg_bw_imc = sum_bw_imc / 4; avg_bw_resc = sum_bw_resc / 4; - avg_diff = avg_bw_resc - avg_bw_imc; + avg_diff = (float)labs(avg_bw_resc - avg_bw_imc) / avg_bw_imc; + avg_diff_per = (int)(avg_diff * 100);
- ret = labs(avg_diff) > MAX_DIFF; + ret = avg_diff_per > MAX_DIFF_PERCENT; ksft_print_msg("%s MBM: diff within %d%%\n", - ret ? "fail:" : "pass:", MAX_DIFF); - ksft_print_msg("avg_diff: %lu\n", labs(avg_diff)); + ret ? "fail:" : "pass:", MAX_DIFF_PERCENT); + ksft_print_msg("avg_diff_per: %d%%\n", avg_diff_per); ksft_print_msg("Span (MB): %d\n", span); ksft_print_msg("avg_bw_imc: %lu\n", avg_bw_imc); ksft_print_msg("avg_bw_resc: %lu\n", avg_bw_resc);