[PATCH v3 14/29] selftests/resctrl: Remove nested calls in perf event handling

Ilpo Järvinen
2023-12-11T12:20:47Z

Perf event handling has functions that are the sole caller of another
perf event handling related function:
- reset_enable_llc_perf() calls perf_event_open_llc_miss()
- perf_event_measure() calls get_llc_perf()

Remove the extra layer of calls to make the code easier to follow by
moving the code into the calling function.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
---
tools/testing/selftests/resctrl/cache.c | 64 ++++++-------------------
1 file changed, 14 insertions(+), 50 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cache.c b/tools/testing/selftests/resctrl/cache.c
index 11d1a6ce14c2..4f846a2e5e26 100644
--- a/tools/testing/selftests/resctrl/cache.c
+++ b/tools/testing/selftests/resctrl/cache.c
@@ -29,24 +29,13 @@ static void initialize_perf_event_attr(void)
pea_llc_miss.disabled = 1;
}

+/* Start counters to log values */
static void ioctl_perf_event_ioc_reset_enable(void)
{
ioctl(fd_lm, PERF_EVENT_IOC_RESET, 0);
ioctl(fd_lm, PERF_EVENT_IOC_ENABLE, 0);
}

-static int perf_event_open_llc_miss(pid_t pid, int cpu_no)
-{
- fd_lm = perf_event_open(&pea_llc_miss, pid, cpu_no, -1,
- PERF_FLAG_FD_CLOEXEC);
- if (fd_lm == -1) {
- ksft_perror("Error opening leader");
- return -1;
- }
-
- return 0;
-}
-
static void initialize_llc_perf(void)
{
memset(&pea_llc_miss, 0, sizeof(struct perf_event_attr));
@@ -62,42 +51,13 @@ static void initialize_llc_perf(void)

static int reset_enable_llc_perf(pid_t pid, int cpu_no)
{
- int ret = 0;
-
- ret = perf_event_open_llc_miss(pid, cpu_no);
- if (ret < 0)
- return ret;
-
- /* Start counters to log values */
- ioctl_perf_event_ioc_reset_enable();
-
- return 0;
-}
-
-/*
- * get_llc_perf: llc cache miss through perf events
- * @llc_perf_miss: LLC miss counter that is filled on success
- *
- * Perf events like HW_CACHE_MISSES could be used to validate number of
- * cache lines allocated.
- *
- * Return: =0 on success. <0 on failure.
- */
-static int get_llc_perf(__u64 *llc_perf_miss)
-{
- int ret;
-
- /* Stop counters after one span to get miss rate */
-
- ioctl(fd_lm, PERF_EVENT_IOC_DISABLE, 0);
-
- ret = read(fd_lm, &rf_cqm, sizeof(struct read_format));
- if (ret == -1) {
- ksft_perror("Could not get llc misses through perf");
+ fd_lm = perf_event_open(&pea_llc_miss, pid, cpu_no, -1, PERF_FLAG_FD_CLOEXEC);
+ if (fd_lm == -1) {
+ ksft_perror("Error opening leader");
return -1;
}

- *llc_perf_miss = rf_cqm.values[0].value;
+ ioctl_perf_event_ioc_reset_enable();

return 0;
}
@@ -178,14 +138,18 @@ static int print_results_cache(const char *filename, int bm_pid, __u64 llc_value
*/
static int perf_event_measure(const char *filename, int bm_pid)
{
- __u64 llc_perf_miss = 0;
int ret;

- ret = get_llc_perf(&llc_perf_miss);
- if (ret < 0)
- return ret;
+ /* Stop counters after one span to get miss rate */
+ ioctl(fd_lm, PERF_EVENT_IOC_DISABLE, 0);
+
+ ret = read(fd_lm, &rf_cqm, sizeof(struct read_format));
+ if (ret == -1) {
+ ksft_perror("Could not get perf value");
+ return -1;
+ }

- return print_results_cache(filename, bm_pid, llc_perf_miss);
+ return print_results_cache(filename, bm_pid, rf_cqm.values[0].value);
}

/*
--
2.30.2