@@ -8,5 +8,6 @@ TEST_GEN_PROGS := resctrl_tests
LOCAL_HDRS += $(wildcard *.h)
include ../lib.mk
+CFLAGS += -I$(top_srcdir)/tools/include
$(OUTPUT)/resctrl_tests: $(wildcard *.c)
@@ -11,6 +11,7 @@
#include <signal.h>
#include <dirent.h>
#include <stdbool.h>
+#include <ctype.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
@@ -21,6 +22,7 @@
#include <sys/eventfd.h>
#include <asm/unistd.h>
#include <linux/perf_event.h>
+#include <linux/compiler.h>
#include "../kselftest.h"
#define MB (1024 * 1024)
@@ -156,8 +158,11 @@ struct perf_event_read {
*/
extern volatile int *value_sink;
+extern int snc_unreliable;
+
extern char llc_occup_path[1024];
+int snc_nodes_per_l3_cache(void);
int get_vendor(void);
bool check_resctrlfs_support(void);
int filter_dmesg(void);
@@ -118,7 +118,7 @@ static bool test_vendor_specific_check(const struct resctrl_test *test)
static void run_single_test(const struct resctrl_test *test, const struct user_params *uparams)
{
- int ret;
+ int ret, snc_mode;
if (test->disabled)
return;
@@ -128,8 +128,15 @@ static void run_single_test(const struct resctrl_test *test, const struct user_p
return;
}
+ snc_mode = snc_nodes_per_l3_cache();
+
ksft_print_msg("Starting %s test ...\n", test->name);
+ if (snc_mode == 1 && snc_unreliable && get_vendor() == ARCH_INTEL) {
+ ksft_test_result_skip("SNC detection unreliable due to offline CPUs. Test results may not be accurate if SNC enabled.\n");
+ return;
+ }
+
if (test_prepare(test)) {
ksft_exit_fail_msg("Abnormal failure when preparing for the test\n");
return;
@@ -13,6 +13,8 @@
#include "resctrl.h"
+int snc_unreliable;
+
static int find_resctrl_mount(char *buffer)
{
FILE *mounts;
@@ -156,6 +158,98 @@ int get_domain_id(const char *resource, int cpu_no, int *domain_id)
return 0;
}
+/*
+ * Count number of CPUs in a /sys bitmap
+ */
+static unsigned int count_sys_bitmap_bits(char *name)
+{
+ FILE *fp = fopen(name, "r");
+ int count = 0, c;
+
+ if (!fp)
+ return 0;
+
+ while ((c = fgetc(fp)) != EOF) {
+ if (!isxdigit(c))
+ continue;
+ switch (c) {
+ case 'f':
+ count++;
+ fallthrough;
+ case '7': case 'b': case 'd': case 'e':
+ count++;
+ fallthrough;
+ case '3': case '5': case '6': case '9': case 'a': case 'c':
+ count++;
+ fallthrough;
+ case '1': case '2': case '4': case '8':
+ count++;
+ break;
+ }
+ }
+ fclose(fp);
+
+ return count;
+}
+
+static bool cpus_offline_empty(void)
+{
+ char offline_cpus_str[64];
+ FILE *fp;
+
+ fp = fopen("/sys/devices/system/cpu/offline", "r");
+ if (!fp) {
+ ksft_perror("Could not open /sys/devices/system/cpu/offline");
+ return 0;
+ }
+
+ if (fscanf(fp, "%63s", offline_cpus_str) < 0) {
+ if (!errno) {
+ fclose(fp);
+ return 1;
+ }
+ ksft_perror("Could not read /sys/devices/system/cpu/offline");
+ }
+
+ fclose(fp);
+
+ return 0;
+}
+
+/*
+ * Detect SNC by comparing #CPUs in node0 with #CPUs sharing LLC with CPU0.
+ * If any CPUs are offline declare the detection as unreliable.
+ */
+int snc_nodes_per_l3_cache(void)
+{
+ int node_cpus, cache_cpus;
+ static int snc_mode;
+
+ if (!snc_mode) {
+ snc_mode = 1;
+ if (!cpus_offline_empty()) {
+ ksft_print_msg("Runtime SNC detection unreliable due to offline CPUs.\n");
+ ksft_print_msg("Setting SNC mode to disabled.\n");
+ snc_unreliable = 1;
+ return snc_mode;
+ }
+ node_cpus = count_sys_bitmap_bits("/sys/devices/system/node/node0/cpumap");
+ cache_cpus = count_sys_bitmap_bits("/sys/devices/system/cpu/cpu0/cache/index3/shared_cpu_map");
+
+ if (!node_cpus || !cache_cpus) {
+ ksft_print_msg("Could not determine Sub-NUMA Cluster mode.\n");
+ snc_unreliable = 1;
+ return snc_mode;
+ }
+ snc_mode = cache_cpus / node_cpus;
+
+ if (snc_mode > 1)
+ ksft_print_msg("SNC-%d mode discovered.\n", snc_mode);
+ }
+
+ return snc_mode;
+}
+
/*
* get_cache_size - Get cache size for a specified CPU
* @cpu_no: CPU number
@@ -211,6 +305,17 @@ int get_cache_size(int cpu_no, const char *cache_type, unsigned long *cache_size
break;
}
+ /*
+ * The amount of cache represented by each bit in the masks
+ * in the schemata file is reduced by a factor equal to SNC
+ * nodes per L3 cache.
+ * E.g. on a SNC-2 system with a 100MB L3 cache a test that
+ * allocates memory from its local SNC node (default behavior
+ * without using libnuma) will only see 50 MB llc_occupancy
+ * with a fully populated L3 mask in the schemata file.
+ */
+ if (cache_num == 3)
+ *cache_size /= snc_nodes_per_l3_cache();
return 0;
}