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

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Date:   Mon, 11 Dec 2023 14:18:11 +0200
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-kselftest@...r.kernel.org,
        Reinette Chatre <reinette.chatre@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
        Maciej Wieczór-Retman 
        <maciej.wieczor-retman@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>
Cc:     linux-kernel@...r.kernel.org,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH v3 14/29] selftests/resctrl: Remove nested calls in perf event handling

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@...ux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.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