#include "resctrl.h"
#include <unistd.h>
-#define RESULT_FILE_NAME1 "result_cat1"
-#define RESULT_FILE_NAME2 "result_cat2"
+#define RESULT_FILE_NAME "result_cat"
#define NUM_OF_RUNS 5
-#define MAX_DIFF_PERCENT 4
-#define MAX_DIFF 1000000
/*
- * Change schemata. Write schemata to specified
- * con_mon grp, mon_grp in resctrl FS.
- * Run 5 times in order to get average values.
+ * Minimum difference in LLC misses between a test with n+1 bits CBM to the
+ * test with n bits is MIN_DIFF_PERCENT_PER_BIT * (n - 1). With e.g. 5 vs 4
+ * bits in the CBM mask, the minimum difference must be at least
+ * MIN_DIFF_PERCENT_PER_BIT * (4 - 1) = 3 percent.
+ *
+ * The relationship between number of used CBM bits and difference in LLC
+ * misses is not expected to be linear. With a small number of bits, the
+ * margin is smaller than with larger number of bits. For selftest purposes,
+ * however, linear approach is enough because ultimately only pass/fail
+ * decision has to be made and distinction between strong and stronger
+ * signal is irrelevant.
*/
-static int cat_setup(struct resctrl_val_param *p)
-{
- char schemata[64];
- int ret = 0;
-
- /* Run NUM_OF_RUNS times */
- if (p->num_of_runs >= NUM_OF_RUNS)
- return END_OF_TESTS;
-
- if (p->num_of_runs == 0) {
- sprintf(schemata, "%lx", p->mask);
- ret = write_schemata(p->ctrlgrp, schemata, p->cpu_no,
- p->resctrl_val);
- }
- p->num_of_runs++;
-
- return ret;
-}
+#define MIN_DIFF_PERCENT_PER_BIT 1UL
static int show_results_info(__u64 sum_llc_val, int no_of_bits,
- unsigned long cache_span, unsigned long max_diff,
- unsigned long max_diff_percent, unsigned long num_of_runs,
- bool platform)
+ unsigned long cache_span,
+ unsigned long min_diff_percent,
+ unsigned long num_of_runs, bool platform,
+ __s64 *prev_avg_llc_val)
{
__u64 avg_llc_val = 0;
- float diff_percent;
- int ret;
+ float avg_diff;
+ int ret = 0;
avg_llc_val = sum_llc_val / num_of_runs;
- diff_percent = ((float)cache_span - avg_llc_val) / cache_span * 100;
+ if (*prev_avg_llc_val) {
+ float delta = (__s64)(avg_llc_val - *prev_avg_llc_val);
- ret = platform && abs((int)diff_percent) > max_diff_percent;
+ avg_diff = delta / *prev_avg_llc_val;
+ ret = platform && (avg_diff * 100) < (float)min_diff_percent;
- ksft_print_msg("%s Check cache miss rate within %lu%%\n",
- ret ? "Fail:" : "Pass:", max_diff_percent);
+ ksft_print_msg("%s Check cache miss rate changed more than %.1f%%\n",
+ ret ? "Fail:" : "Pass:", (float)min_diff_percent);
- ksft_print_msg("Percent diff=%d\n", abs((int)diff_percent));
+ ksft_print_msg("Percent diff=%.1f\n", avg_diff * 100);
+ }
+ *prev_avg_llc_val = avg_llc_val;
show_cache_info(no_of_bits, avg_llc_val, cache_span, true);
return ret;
}
-static int check_results(struct resctrl_val_param *param, size_t span)
+/* Remove the highest bit from CBM */
+static unsigned long next_mask(unsigned long current_mask)
+{
+ return current_mask & (current_mask >> 1);
+}
+
+static int check_results(struct resctrl_val_param *param, const char *cache_type,
+ unsigned long cache_total_size, unsigned long full_cache_mask,
+ unsigned long current_mask)
{
char *token_array[8], temp[512];
- int runs = 0, no_of_bits = 0;
__u64 sum_llc_perf_miss = 0;
+ __s64 prev_avg_llc_val = 0;
+ unsigned long alloc_size;
+ int runs = 0;
+ int fail = 0;
+ int ret;
FILE *fp;
ksft_print_msg("Checking for pass/fail\n");
while (fgets(temp, sizeof(temp), fp)) {
char *token = strtok(temp, ":\t");
int fields = 0;
+ int bits;
while (token) {
token_array[fields++] = token;
token = strtok(NULL, ":\t");
}
- /*
- * Discard the first value which is inaccurate due to monitoring
- * setup transition phase.
- */
- if (runs > 0)
- sum_llc_perf_miss += strtoull(token_array[3], NULL, 0);
+
+ sum_llc_perf_miss += strtoull(token_array[3], NULL, 0);
runs++;
+
+ if (runs < NUM_OF_RUNS)
+ continue;
+
+ if (!current_mask) {
+ ksft_print_msg("Unexpected empty cache mask\n");
+ break;
+ }
+
+ alloc_size = cache_portion_size(cache_total_size, current_mask, full_cache_mask);
+
+ bits = count_bits(current_mask);
+
+ ret = show_results_info(sum_llc_perf_miss, bits,
+ alloc_size / 64,
+ MIN_DIFF_PERCENT_PER_BIT * (bits - 1),
+ runs, get_vendor() == ARCH_INTEL,
+ &prev_avg_llc_val);
+ if (ret)
+ fail = 1;
+
+ runs = 0;
+ sum_llc_perf_miss = 0;
+ current_mask = next_mask(current_mask);
}
fclose(fp);
- no_of_bits = count_bits(param->mask);
- return show_results_info(sum_llc_perf_miss, no_of_bits, span / 64,
- MAX_DIFF, MAX_DIFF_PERCENT, runs - 1,
- get_vendor() == ARCH_INTEL);
+ return fail;
}
void cat_test_cleanup(void)
{
- remove(RESULT_FILE_NAME1);
- remove(RESULT_FILE_NAME2);
+ remove(RESULT_FILE_NAME);
}
/*
* cat_test - Execute CAT benchmark and measure cache misses
* @param: Parameters passed to cat_test()
* @span: Buffer size for the benchmark
+ * @current_mask Start mask for the first iteration
+ *
+ * Run CAT selftest by varying the allocated cache portion and comparing the
+ * impact on cache misses (the result analysis is done in check_results()
+ * and show_results_info(), not in this function).
+ *
+ * One bit is removed from the CAT allocation bit mask (in current_mask) for
+ * each subsequent test which keeps reducing the size of the allocated cache
+ * portion. A single test flushes the buffer, reads it to warm up the cache,
+ * and reads the buffer again. The cache misses are measured during the last
+ * read pass.
*
* Return: 0 when the test was run, < 0 on error.
*/
-static int cat_test(struct resctrl_val_param *param, size_t span)
+static int cat_test(struct resctrl_val_param *param, size_t span, unsigned long current_mask)
{
- int memflush = 1, operation = 0, ret = 0;
char *resctrl_val = param->resctrl_val;
struct perf_event_read pe_read;
struct perf_event_attr pea;
+ unsigned char *buf;
+ char schemata[64];
+ int ret, i, pe_fd;
pid_t bm_pid;
- int pe_fd;
if (strcmp(param->filename, "") == 0)
sprintf(param->filename, "stdio");
if (pe_fd < 0)
return pe_fd;
- /* Test runs until the callback setup() tells the test to stop. */
- while (1) {
- ret = param->setup(param);
- if (ret == END_OF_TESTS) {
- ret = 0;
- break;
- }
- if (ret < 0)
- break;
+ buf = alloc_buffer(span, 1);
+ if (!buf) {
+ ret = -1;
+ goto pe_close;
+ }
- ret = perf_event_reset_enable(pe_fd);
+ while (current_mask) {
+ snprintf(schemata, sizeof(schemata), "%lx", param->mask & ~current_mask);
+ ret = write_schemata("", schemata, param->cpu_no, param->resctrl_val);
if (ret)
- goto pe_close;
+ goto free_buf;
+ snprintf(schemata, sizeof(schemata), "%lx", current_mask);
+ ret = write_schemata(param->ctrlgrp, schemata, param->cpu_no, param->resctrl_val);
+ if (ret)
+ goto free_buf;
- if (run_fill_buf(span, memflush, operation, true)) {
- fprintf(stderr, "Error-running fill buffer\n");
- ret = -1;
- goto pe_close;
- }
+ for (i = 0; i < NUM_OF_RUNS; i++) {
+ mem_flush(buf, span);
+ fill_cache_read(buf, span, true);
- sleep(1);
- ret = perf_event_measure(pe_fd, &pe_read, param->filename, bm_pid);
- if (ret)
- goto pe_close;
- }
+ ret = perf_event_reset_enable(pe_fd);
+ if (ret)
+ goto free_buf;
- return ret;
+ fill_cache_read(buf, span, true);
+ ret = perf_event_measure(pe_fd, &pe_read, param->filename, bm_pid);
+ if (ret)
+ goto free_buf;
+ }
+ current_mask = next_mask(current_mask);
+ }
+
+free_buf:
+ free(buf);
pe_close:
close(pe_fd);
+
return ret;
}
int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
{
- unsigned long full_cache_mask, long_mask;
- unsigned long l_mask, l_mask_1;
- int ret, pipefd[2], sibling_cpu_no;
+ unsigned long long_mask, start_mask, full_cache_mask;
unsigned long cache_total_size = 0;
+ unsigned int start;
int count_of_bits;
- char pipe_message;
size_t span;
+ int ret;
ret = get_full_cbm(cache_type, &full_cache_mask);
if (ret)
return ret;
ksft_print_msg("Cache size :%lu\n", cache_total_size);
- count_of_bits = count_bits(long_mask);
+ count_of_bits = count_contiguous_bits(long_mask, &start);
if (!n)
n = count_of_bits / 2;
count_of_bits - 1);
return -1;
}
-
- /* Get core id from same socket for running another thread */
- sibling_cpu_no = get_core_sibling(cpu_no);
- if (sibling_cpu_no < 0)
- return -1;
+ start_mask = create_bit_mask(start, n);
struct resctrl_val_param param = {
.resctrl_val = CAT_STR,
.cpu_no = cpu_no,
- .setup = cat_setup,
+ .ctrlgrp = "c1",
+ .filename = RESULT_FILE_NAME,
+ .num_of_runs = 0,
};
-
- l_mask = long_mask >> n;
- l_mask_1 = ~l_mask & long_mask;
-
- /* Set param values for parent thread which will be allocated bitmask
- * with (max_bits - n) bits
- */
- span = cache_portion_size(cache_total_size, l_mask, full_cache_mask);
- strcpy(param.ctrlgrp, "c2");
- strcpy(param.mongrp, "m2");
- strcpy(param.filename, RESULT_FILE_NAME2);
- param.mask = l_mask;
- param.num_of_runs = 0;
-
- if (pipe(pipefd)) {
- ksft_perror("Unable to create pipe");
- return -1;
- }
-
- fflush(stdout);
- bm_pid = fork();
-
- /* Set param values for child thread which will be allocated bitmask
- * with n bits
- */
- if (bm_pid == 0) {
- param.mask = l_mask_1;
- strcpy(param.ctrlgrp, "c1");
- strcpy(param.mongrp, "m1");
- span = cache_portion_size(cache_total_size, l_mask_1, full_cache_mask);
- strcpy(param.filename, RESULT_FILE_NAME1);
- param.num_of_runs = 0;
- param.cpu_no = sibling_cpu_no;
- }
+ param.mask = long_mask;
+ span = cache_portion_size(cache_total_size, start_mask, full_cache_mask);
remove(param.filename);
- ret = cat_test(¶m, span);
- if (ret == 0)
- ret = check_results(¶m, span);
-
- if (bm_pid == 0) {
- /* Tell parent that child is ready */
- close(pipefd[0]);
- pipe_message = 1;
- if (write(pipefd[1], &pipe_message, sizeof(pipe_message)) <
- sizeof(pipe_message))
- /*
- * Just print the error message.
- * Let while(1) run and wait for itself to be killed.
- */
- ksft_perror("Failed signaling parent process");
-
- close(pipefd[1]);
- while (1)
- ;
- } else {
- /* Parent waits for child to be ready. */
- close(pipefd[1]);
- pipe_message = 0;
- while (pipe_message != 1) {
- if (read(pipefd[0], &pipe_message,
- sizeof(pipe_message)) < sizeof(pipe_message)) {
- ksft_perror("Failed reading from child process");
- break;
- }
- }
- close(pipefd[0]);
- kill(bm_pid, SIGKILL);
- }
+ ret = cat_test(¶m, span, start_mask);
+ if (ret)
+ goto out;
+ ret = check_results(¶m, cache_type, cache_total_size, full_cache_mask, start_mask);
+out:
cat_test_cleanup();
return ret;
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