[PATCH v4 3/3] selftests/resctrl: Enable dynamic management of IMC counters via linked list
Yifan Wu
wuyifan50 at huawei.com
Sat Aug 1 02:24:29 PDT 2026
Remove the static array and the count and upper limit checks during
initialization, allowing the system to dynamically use all available
IMC counters detected by hardware.
Reviewed-by: Reinette Chatre <reinette.chatre at intel.com>
Signed-off-by: Yifan Wu <wuyifan50 at huawei.com>
---
tools/testing/selftests/resctrl/resctrl_val.c | 94 ++++++++-----------
1 file changed, 41 insertions(+), 53 deletions(-)
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index f4111da26fc2..7e7d0f9cc249 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -14,7 +14,6 @@
#define READ_FILE_NAME "cas_count_read"
#define DYN_PMU_PATH "/sys/bus/event_source/devices"
#define SCALE 0.00006103515625
-#define MAX_IMCS 40
#define MAX_TOKENS 5
#define CON_MBM_LOCAL_BYTES_PATH \
@@ -37,8 +36,6 @@ struct imc_counter_config {
};
static char mbm_total_path[1024];
-static int imcs;
-static struct imc_counter_config imc_counters_config[MAX_IMCS];
LIST_HEAD(imc_counters_list);
static const struct resctrl_test *current_test;
@@ -107,12 +104,11 @@ static int open_perf_read_event(int cpu_no, struct imc_counter_config *imc_count
return 0;
}
-static int parse_imc_read_bw_events(char *imc_dir, unsigned int type,
- unsigned int *count)
+static int parse_imc_read_bw_events(char *imc_dir, unsigned int type)
{
char imc_events_dir[PATH_MAX], imc_counter_cfg[PATH_MAX];
struct imc_counter_config *imc_counter;
- unsigned int orig_count = *count;
+ bool found_event = false;
char cas_count_cfg[1024];
struct dirent *ep;
int path_len;
@@ -162,23 +158,18 @@ static int parse_imc_read_bw_events(char *imc_dir, unsigned int type,
ksft_perror("Could not get iMC cas count read");
goto out_close;
}
- if (*count >= MAX_IMCS) {
- ksft_print_msg("Maximum iMC count exceeded\n");
- goto out_close;
- }
imc_counter = calloc(1, sizeof(*imc_counter));
if (!imc_counter) {
ksft_perror("Unable to allocate memory for iMC counters");
goto out_close;
}
- imc_counters_config[*count].type = type;
- get_read_event_and_umask(cas_count_cfg, &imc_counters_config[*count]);
- /* Do not fail after incrementing *count. */
- *count += 1;
+ imc_counter->type = type;
+ get_read_event_and_umask(cas_count_cfg, imc_counter);
list_add(&imc_counter->entry, &imc_counters_list);
+ found_event = true;
}
- if (*count == orig_count) {
+ if (!found_event) {
ksft_print_msg("Unable to find events in %s\n", imc_events_dir);
goto out_close;
}
@@ -193,7 +184,7 @@ static int parse_imc_read_bw_events(char *imc_dir, unsigned int type,
}
/* Get type and config of an iMC counter's read event. */
-static int read_from_imc_dir(char *imc_dir, unsigned int *count)
+static int read_from_imc_dir(char *imc_dir)
{
char imc_counter_type[PATH_MAX];
unsigned int type;
@@ -221,7 +212,7 @@ static int read_from_imc_dir(char *imc_dir, unsigned int *count)
ksft_perror("Could not get iMC type");
return -1;
}
- ret = parse_imc_read_bw_events(imc_dir, type, count);
+ ret = parse_imc_read_bw_events(imc_dir, type);
if (ret) {
ksft_print_msg("Unable to parse bandwidth event and umask\n");
return ret;
@@ -231,21 +222,18 @@ static int read_from_imc_dir(char *imc_dir, unsigned int *count)
}
/*
- * A system can have 'n' number of iMC (Integrated Memory Controller)
- * counters, get that 'n'. Discover the properties of the available
- * counters in support of needed performance measurement via perf.
- * For each iMC counter get it's type and config. Also obtain each
- * counter's event and umask for the memory read events that will be
- * measured.
+ * Discover the properties of the available iMC (Integrated Memory Controller)
+ * counters in support of needed performance measurement via perf. For each iMC
+ * counter get it's type and config. Also obtain each counter's event and umask
+ * for the memory read events that will be measured.
*
- * Enumerate all these details into an array of structures.
+ * Enumerate all these details into a linked list of structures.
*
* Return: >= 0 on success. < 0 on failure.
*/
-static int num_of_imcs(void)
+static int enumerate_imcs(void)
{
char imc_dir[512], *temp;
- unsigned int count = 0;
struct dirent *ep;
int ret;
DIR *dp;
@@ -274,7 +262,7 @@ static int num_of_imcs(void)
if (temp[0] >= '0' && temp[0] <= '9') {
sprintf(imc_dir, "%s/%s/", DYN_PMU_PATH,
ep->d_name);
- ret = read_from_imc_dir(imc_dir, &count);
+ ret = read_from_imc_dir(imc_dir);
if (ret) {
closedir(dp);
@@ -283,7 +271,7 @@ static int num_of_imcs(void)
}
}
closedir(dp);
- if (count == 0) {
+ if (list_empty(&imc_counters_list)) {
ksft_print_msg("Unable to find iMC counters\n");
return -1;
@@ -294,20 +282,21 @@ static int num_of_imcs(void)
return -1;
}
- return count;
+ return 0;
}
int initialize_read_mem_bw_imc(void)
{
- int imc;
+ struct imc_counter_config *imc_counter;
+ int ret;
- imcs = num_of_imcs();
- if (imcs <= 0)
- return imcs;
+ ret = enumerate_imcs();
+ if (ret < 0)
+ return ret;
/* Initialize perf_event_attr structures for all iMC's */
- for (imc = 0; imc < imcs; imc++)
- read_mem_bw_initialize_perf_event_attr(&imc_counters_config[imc]);
+ list_for_each_entry(imc_counter, &imc_counters_list, entry)
+ read_mem_bw_initialize_perf_event_attr(imc_counter);
return 0;
}
@@ -324,11 +313,11 @@ void cleanup_read_mem_bw_imc(void)
static void perf_close_imc_read_mem_bw(void)
{
- int mc;
+ struct imc_counter_config *imc_counter;
- for (mc = 0; mc < imcs; mc++) {
- if (imc_counters_config[mc].fd != -1)
- close(imc_counters_config[mc].fd);
+ list_for_each_entry(imc_counter, &imc_counters_list, entry) {
+ if (imc_counter->fd != -1)
+ close(imc_counter->fd);
}
}
@@ -340,13 +329,14 @@ static void perf_close_imc_read_mem_bw(void)
*/
static int perf_open_imc_read_mem_bw(int cpu_no)
{
- int imc, ret;
+ struct imc_counter_config *imc_counter;
+ int ret;
- for (imc = 0; imc < imcs; imc++)
- imc_counters_config[imc].fd = -1;
+ list_for_each_entry(imc_counter, &imc_counters_list, entry)
+ imc_counter->fd = -1;
- for (imc = 0; imc < imcs; imc++) {
- ret = open_perf_read_event(cpu_no, &imc_counters_config[imc]);
+ list_for_each_entry(imc_counter, &imc_counters_list, entry) {
+ ret = open_perf_read_event(cpu_no, imc_counter);
if (ret)
goto close_fds;
}
@@ -366,16 +356,16 @@ static int perf_open_imc_read_mem_bw(int cpu_no)
*/
static void do_imc_read_mem_bw_test(void)
{
- int imc;
+ struct imc_counter_config *imc_counter;
- for (imc = 0; imc < imcs; imc++)
- read_mem_bw_ioctl_perf_event_ioc_reset_enable(&imc_counters_config[imc]);
+ list_for_each_entry(imc_counter, &imc_counters_list, entry)
+ read_mem_bw_ioctl_perf_event_ioc_reset_enable(imc_counter);
sleep(1);
/* Stop counters after a second to get results. */
- for (imc = 0; imc < imcs; imc++)
- read_mem_bw_ioctl_perf_event_ioc_disable(&imc_counters_config[imc]);
+ list_for_each_entry(imc_counter, &imc_counters_list, entry)
+ read_mem_bw_ioctl_perf_event_ioc_disable(imc_counter);
}
/*
@@ -390,17 +380,15 @@ static void do_imc_read_mem_bw_test(void)
static int get_read_mem_bw_imc(float *bw_imc)
{
float reads = 0, of_mul_read = 1;
- int imc;
+ struct imc_counter_config *r;
/*
* Log read event values from all iMC counters into
* struct imc_counter_config.
* Take overflow into consideration before calculating total bandwidth.
*/
- for (imc = 0; imc < imcs; imc++) {
+ list_for_each_entry(r, &imc_counters_list, entry) {
struct membw_read_format measurement;
- struct imc_counter_config *r =
- &imc_counters_config[imc];
if (read(r->fd, &measurement, sizeof(measurement)) == -1) {
ksft_perror("Couldn't get read bandwidth through iMC");
--
2.33.0
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