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Subject[PATCH V1 11/13] selftests/resctrl: Change Cache Quality Monitoring (CQM) test
Date
The present CQM test runs fill_buff continuously with some user specified
buffer size and reads cqm_llc_occupancy every 1 second and tests if resctrl
reported value is in 15% range of buffer that fill_buff is working on. If
the difference is greater than 15% the test fails. This test assumes that
the buffer fill_buff is working on will be identity mapped into cache from
memory i.e. there won't be any overlap. But that might not always be true
because of the way cache indexing works (two physical addresses could get
indexed into the same cache line). If this happens, cqm_llc_occupancy will
be less than buffer size and we cannot guarantee the percentage by which
this might be less. Another issue with the test case is that, although it
has 15% of guard band, the cache occupied by code (or other parts) of the
process may not be within this range. While we are actively looking into
approximating llc_occupancy through perf, fix this test case with the help
of CAT.

The new CQM test runs fill_buff continuously with a buffer size that is
much greater than cache size and uses CAT to change schemata (from 1 bit to
max_bits available without shareable bits). For every change in schemata,
it then averages cqm_llc_occupancy and checks if it is less than allocated
cache size (with 5% guard band). If the average cqm_llc_occupancy is less
than allocated cache size, the test passes. Please note that there is no
lower bound on the expected cqm_llc_occupancy because presently that cannot
be determined.

Note:
The new test case assumes that
1. The system supports CAT
2. CAT is working as expected on the system

Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Suggested-by: Tony Luck <tony.luck@intel.com>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
---
tools/testing/selftests/resctrl/cache.c | 4 +
tools/testing/selftests/resctrl/cqm_test.c | 203 +++++++++++++++---------
tools/testing/selftests/resctrl/resctrl.h | 3 +-
tools/testing/selftests/resctrl/resctrl_tests.c | 6 +-
tools/testing/selftests/resctrl/resctrl_val.c | 22 +--
tools/testing/selftests/resctrl/resctrlfs.c | 6 +-
6 files changed, 143 insertions(+), 101 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cache.c b/tools/testing/selftests/resctrl/cache.c
index e30cdd7b851c..ca794ad6fcfc 100644
--- a/tools/testing/selftests/resctrl/cache.c
+++ b/tools/testing/selftests/resctrl/cache.c
@@ -224,11 +224,15 @@ int measure_cache_vals(struct resctrl_val_param *param, int bm_pid)

/* Measure llc occupancy from resctrl */
if (!strcmp(param->resctrl_val, "cqm")) {
+ /* Sleep for a second so that benchmark gets to run */
+ sleep(1);
+
ret = get_llc_occu_resctrl(&llc_occu_resc);
if (ret < 0)
return ret;
llc_value = llc_occu_resc;
}
+
ret = print_results_cache(param->filename, bm_pid, llc_value);
if (ret)
return ret;
diff --git a/tools/testing/selftests/resctrl/cqm_test.c b/tools/testing/selftests/resctrl/cqm_test.c
index f27b0363e518..3406c04ff110 100644
--- a/tools/testing/selftests/resctrl/cqm_test.c
+++ b/tools/testing/selftests/resctrl/cqm_test.c
@@ -13,73 +13,74 @@

#define RESULT_FILE_NAME "result_cqm"
#define NUM_OF_RUNS 5
-#define MAX_DIFF 2000000
-#define MAX_DIFF_PERCENT 15
+#define MAX_DIFF_PERCENT 5

-int count_of_bits;
char cbm_mask[256];
-unsigned long long_mask;
-unsigned long cache_size;

-static int cqm_setup(struct resctrl_val_param *p)
-{
- /* Run NUM_OF_RUNS times */
- if (p->num_of_runs >= NUM_OF_RUNS)
- return -1;
-
- p->num_of_runs++;
-
- return 0;
-}
+static int count_of_bits, count_of_shareable_bits;
+static unsigned long cache_size, shareable_mask;

-static void show_cache_info(unsigned long sum_llc_occu_resc, int no_of_bits,
- unsigned long span)
+static void show_cache_info(unsigned long *llc_occu_resc)
{
- unsigned long avg_llc_occu_resc = 0;
- float diff_percent;
- long avg_diff = 0;
- bool res;
+ int bits, runs;
+ bool failed = false;

- avg_llc_occu_resc = sum_llc_occu_resc / (NUM_OF_RUNS - 1);
- avg_diff = (long)abs(span - avg_llc_occu_resc);
-
- diff_percent = (((float)span - avg_llc_occu_resc) / span) * 100;
+ printf("# Results are displayed in (Bytes)\n");

- if ((abs((int)diff_percent) <= MAX_DIFF_PERCENT) ||
- (abs(avg_diff) <= MAX_DIFF))
- res = true;
- else
- res = false;
+ for (bits = 0; bits < count_of_bits - count_of_shareable_bits; bits++) {
+ unsigned long avg_llc_occu_resc, sum_llc_occu_resc = 0;
+ unsigned long alloc_llc, mask = 0;
+ int llc_occu_diff, i;
+
+ /*
+ * The first run is discarded due to inaccurate value from
+ * phase transition.
+ */
+ for (runs = NUM_OF_RUNS * bits + 1;
+ runs < NUM_OF_RUNS * bits + NUM_OF_RUNS; runs++)
+ sum_llc_occu_resc += llc_occu_resc[runs];
+
+ avg_llc_occu_resc = sum_llc_occu_resc / (NUM_OF_RUNS - 1);
+ alloc_llc = cache_size * ((float)(bits + 1) / count_of_bits);
+ llc_occu_diff = avg_llc_occu_resc - alloc_llc;
+
+ for (i = 0; i < bits + 1; i++) {
+ mask <<= 1;
+ mask |= 1;
+ }

- printf("%sok CQM: diff within %d, %d\%%\n", res ? "" : "not ",
- MAX_DIFF, (int)MAX_DIFF_PERCENT);
+ if (llc_occu_diff > 0 &&
+ llc_occu_diff > alloc_llc * ((float)MAX_DIFF_PERCENT / 100))
+ failed = true;

- printf("# diff: %ld\n", avg_diff);
- printf("# percent diff=%d\n", abs((int)diff_percent));
- printf("# Results are displayed in (Bytes)\n");
- printf("# Number of bits: %d\n", no_of_bits);
- printf("# Avg_llc_occu_resc: %lu\n", avg_llc_occu_resc);
- printf("# llc_occu_exp (span): %lu\n", span);
+ printf("%sok CQM: diff within %d%% for mask %lx\n",
+ failed ? "not " : "", MAX_DIFF_PERCENT, mask);
+ printf("# alloc_llc_cache_size: %lu\n", alloc_llc);
+ printf("# avg_llc_occu_resc: %lu\n", avg_llc_occu_resc);
+ tests_run++;
+ }

+ printf("%sok schemata change for CQM%s\n", failed ? "not " : "",
+ failed ? " # at least one test failed" : "");
tests_run++;
}

-static int check_results(struct resctrl_val_param *param, int no_of_bits)
+static int check_results(void)
{
- char *token_array[8], temp[512];
- unsigned long sum_llc_occu_resc = 0;
- int runs = 0;
+ char *token_array[8], output[] = RESULT_FILE_NAME, temp[512];
+ unsigned long llc_occu_resc[count_of_bits * NUM_OF_RUNS];
+ int runs;
FILE *fp;

- printf("# checking for pass/fail\n");
- fp = fopen(param->filename, "r");
+ fp = fopen(output, "r");
if (!fp) {
- perror("# Error in opening file\n");
+ perror(output);

return errno;
}

- while (fgets(temp, 1024, fp)) {
+ runs = 0;
+ while (fgets(temp, sizeof(temp), fp)) {
char *token = strtok(temp, ":\t");
int fields = 0;

@@ -88,13 +89,14 @@ static int check_results(struct resctrl_val_param *param, int no_of_bits)
token = strtok(NULL, ":\t");
}

- /* Field 3 is llc occ resc value */
- if (runs > 0)
- sum_llc_occu_resc += strtoul(token_array[3], NULL, 0);
+ /* Field 3 is resctrl LLC occupancy value */
+ llc_occu_resc[runs] = strtoul(token_array[3], NULL, 0);
runs++;
}
+
fclose(fp);
- show_cache_info(sum_llc_occu_resc, no_of_bits, param->span);
+
+ show_cache_info(llc_occu_resc);

return 0;
}
@@ -104,62 +106,107 @@ void cqm_test_cleanup(void)
remove(RESULT_FILE_NAME);
}

-int cqm_resctrl_val(int cpu_no, int n, char **benchmark_cmd)
+/*
+ * Change schemata from 1 to count_of_bits - 1. Write schemata to specified
+ * con_mon grp, mon_grp in resctrl FS. For each allocation, run "NUM_OF_RUNS"
+ * times to get average values.
+ */
+static int cqm_setup(struct resctrl_val_param *p)
{
- int ret, mum_resctrlfs;
+ static int runs_per_allocation = 0, num_of_bits = 1;
+ unsigned long mask = 0;
+ char schemata[64];
+ int i, ret;

- cache_size = 0;
- mum_resctrlfs = 1;
+ if (runs_per_allocation >= NUM_OF_RUNS)
+ runs_per_allocation = 0;

- ret = remount_resctrlfs(mum_resctrlfs);
- if (ret)
- return ret;
+ /* Only set up schemata once every NUM_OF_RUNS of allocations */
+ if (runs_per_allocation++ != 0)
+ return 0;

- if (!validate_resctrl_feature_request("cqm"))
+ if (num_of_bits > count_of_bits - count_of_shareable_bits)
return -1;

- ret = get_cbm_mask("L3");
- if (ret)
- return ret;
-
- long_mask = strtoul(cbm_mask, NULL, 16);
+ /* Prepare cbm mask without any shareable bits */
+ for (i = 0; i < num_of_bits; i++) {
+ mask <<= 1;
+ mask |= 1;
+ }
+ mask = ~shareable_mask & mask;

- ret = get_cache_size(cpu_no, "L3", &cache_size);
+ sprintf(schemata, "%lx", mask);
+ ret = write_schemata(p->ctrlgrp, schemata, p->cpu_no, "cat");
if (ret)
return ret;
- printf("cache size :%lu\n", cache_size);

- count_of_bits = count_bits(long_mask);
+ p->mask = mask;
+ num_of_bits++;

- if (n < 1 || n > count_of_bits) {
- printf("Invalid input value for numbr_of_bits n!\n");
- printf("Please Enter value in range 1 to %d\n", count_of_bits);
- return -1;
- }
+ return 0;
+}

+int cqm_schemata_change(int cpu_no, int span, char *cache_type,
+ char **benchmark_cmd)
+{
struct resctrl_val_param param = {
.resctrl_val = "cqm",
.ctrlgrp = "c1",
.mongrp = "m1",
.cpu_no = cpu_no,
+ .span = span,
.mum_resctrlfs = 0,
.filename = RESULT_FILE_NAME,
- .mask = ~(long_mask << n) & long_mask,
- .span = cache_size * n / count_of_bits,
.num_of_runs = 0,
- .setup = cqm_setup,
+ .setup = cqm_setup
};
+ int ret;
+ char schemata[64];
+ unsigned long long_mask;

- if (strcmp(benchmark_cmd[0], "fill_buf") == 0)
- sprintf(benchmark_cmd[1], "%lu", param.span);
+ ret = remount_resctrlfs(1);
+ if (ret)
+ return ret;

- remove(RESULT_FILE_NAME);
+ /* Check for both 'cat' and 'cqm' because CQM is validated using CAT */
+ if (!validate_resctrl_feature_request("cqm"))
+ return -1;
+
+ if (!validate_resctrl_feature_request("cat"))
+ return -1;
+
+ ret = get_cache_size(cpu_no, cache_type, &cache_size);
+ if (ret)
+ return ret;
+ printf("# cache size: %lu\n", cache_size);
+
+ ret = get_cbm_mask(cache_type);
+ if (ret)
+ return ret;
+
+ long_mask = strtoul(cbm_mask, NULL, 16);
+ count_of_bits = count_bits(long_mask);
+
+ /*
+ * Change root con_mon grp schemata to minimum (i.e. '1' bit) so that
+ * test could use all other bits
+ */
+ sprintf(schemata, "%x", 1);
+ ret = write_schemata("", schemata, cpu_no, "cqm");
+ if (ret)
+ return ret;
+
+ ret = get_shareable_mask(cache_type, &shareable_mask);
+ if (ret)
+ return ret;
+
+ count_of_shareable_bits = count_bits(shareable_mask);

ret = resctrl_val(benchmark_cmd, &param);
if (ret)
return ret;

- ret = check_results(&param, n);
+ ret = check_results();
if (ret)
return ret;

diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 79148cbbd7a4..cb67ad689475 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -103,7 +103,8 @@ int setup_critical_process(pid_t pid, struct resctrl_val_param *param);
int run_critical_process(pid_t pid, struct resctrl_val_param *param);
void cat_test_cleanup(void);
int cat_perf_miss_val(int cpu_no, int no_of_bits, char *cache_type);
-int cqm_resctrl_val(int cpu_no, int n, char **benchmark_cmd);
+int cqm_schemata_change(int cpu_no, int span, char *cache_type,
+ char **benchmark_cmd);
unsigned int count_bits(unsigned long n);
void cqm_test_cleanup(void);
int get_core_sibling(int cpu_no);
diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
index 60db128312a6..3c408c636b6d 100644
--- a/tools/testing/selftests/resctrl/resctrl_tests.c
+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
@@ -180,9 +180,11 @@ int main(int argc, char **argv)

if (cqm_test) {
printf("# Starting CQM test ...\n");
- if (!has_ben)
+ if (!has_ben) {
+ sprintf(benchmark_cmd[1], "%d", span);
sprintf(benchmark_cmd[5], "%s", "cqm");
- res = cqm_resctrl_val(cpu_no, no_of_bits, benchmark_cmd);
+ }
+ res = cqm_schemata_change(cpu_no, span, "L3", benchmark_cmd);
printf("%sok CQM: test\n", res ? "not " : "");
cqm_test_cleanup();
tests_run++;
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index 271cb5c976f5..c59fad6cb9b0 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -705,29 +705,21 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
goto out;
}

- /* Give benchmark enough time to fully run */
- sleep(1);
-
/* Test runs until the callback setup() tells the test to stop. */
while (1) {
+ ret = param->setup(param);
+ if (ret) {
+ ret = 0;
+ break;
+ }
+
+ /* Measure vals sleeps for a second */
if ((strcmp(resctrl_val, "mbm") == 0) ||
(strcmp(resctrl_val, "mba") == 0)) {
- ret = param->setup(param);
- if (ret) {
- ret = 0;
- break;
- }
-
ret = measure_vals(param, &bw_resc_start);
if (ret)
break;
} else if (strcmp(resctrl_val, "cqm") == 0) {
- ret = param->setup(param);
- if (ret) {
- ret = 0;
- break;
- }
- sleep(1);
ret = measure_cache_vals(param, bm_pid);
if (ret)
break;
diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index 52452bb0178a..bd81a13ff9df 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -365,11 +365,7 @@ void run_benchmark(int signum, siginfo_t *info, void *ucontext)
memflush = atoi(benchmark_cmd[3]);
operation = atoi(benchmark_cmd[4]);
sprintf(resctrl_val, "%s", benchmark_cmd[5]);
-
- if (strcmp(resctrl_val, "cqm") != 0)
- buffer_span = span * MB;
- else
- buffer_span = span;
+ buffer_span = span * MB;

if (run_fill_buf(buffer_span, malloc_and_init_memory, memflush,
operation, resctrl_val))
--
2.7.4
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