[PATCH 2/4] selftests/resctrl: SNC support for CMT

[Maciej Wieczor-Retman]

Cache Monitoring Technology (CMT) works by measuring how much data in L3
cache is occupied by a given process identified by its Resource
Monitoring ID (RMID).

On systems with Sub-Numa Clusters (SNC) enabled, a process can occupy
not only the cache that belongs to its own NUMA node but also pieces of
other NUMA nodes' caches that lie on the same socket.

A simple correction to make the CMT selftest NUMA-aware is to sum values
reported by all nodes on the same socket for a given RMID.

Reported-by: "Shaopeng Tan (Fujitsu)" <tan.shaopeng@xxxxxxxxxxx>
Closes: https://lore.kernel.org/all/TYAPR01MB6330B9B17686EF426D2C3F308B25A@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>
---
 tools/testing/selftests/resctrl/cache.c       | 17 +++++++++++------
 tools/testing/selftests/resctrl/resctrl.h     |  4 +++-
 tools/testing/selftests/resctrl/resctrl_val.c |  9 ++++++---
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cache.c b/tools/testing/selftests/resctrl/cache.c
index 1b339d6bbff1..dab81920033b 100644
--- a/tools/testing/selftests/resctrl/cache.c
+++ b/tools/testing/selftests/resctrl/cache.c
@@ -161,16 +161,21 @@ int perf_event_measure(int pe_fd, struct perf_event_read *pe_read,
  *
  * Return: =0 on success. <0 on failure.
  */
-int measure_llc_resctrl(const char *filename, int bm_pid)
+int measure_llc_resctrl(const char *filename, int bm_pid, const char *ctrlgrp,
+			const char *mongrp, int res_id)
 {
-	unsigned long llc_occu_resc = 0;
+	unsigned long sum = 0, llc_occu_resc = 0;
 	int ret;
 
-	ret = get_llc_occu_resctrl(&llc_occu_resc);
-	if (ret < 0)
-		return ret;
+	for (int i = 0 ; i < snc_ways() ; i++) {
+		set_cmt_path(ctrlgrp, mongrp, res_id + i);
+		ret = get_llc_occu_resctrl(&llc_occu_resc);
+		if (ret < 0)
+			return ret;
+		sum += llc_occu_resc;
+	}
 
-	return print_results_cache(filename, bm_pid, llc_occu_resc);
+	return print_results_cache(filename, bm_pid, sum);
 }
 
 /*
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 41811e87f81c..178fb2eab13a 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -133,6 +133,7 @@ extern pid_t bm_pid, ppid;
 extern char llc_occup_path[1024];
 
 int snc_ways(void);
+void set_cmt_path(const char *ctrlgrp, const char *mongrp, char sock_num);
 int get_vendor(void);
 bool check_resctrlfs_support(void);
 int filter_dmesg(void);
@@ -182,7 +183,8 @@ int perf_open(struct perf_event_attr *pea, pid_t pid, int cpu_no);
 int perf_event_reset_enable(int pe_fd);
 int perf_event_measure(int pe_fd, struct perf_event_read *pe_read,
 		       const char *filename, int bm_pid);
-int measure_llc_resctrl(const char *filename, int bm_pid);
+int measure_llc_resctrl(const char *filename, int bm_pid, const char *ctrlgrp,
+			const char *mongrp, int res_id);
 void show_cache_info(int no_of_bits, __u64 avg_llc_val, size_t cache_span, bool lines);
 
 /*
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index 5a49f07a6c85..e75e3923ebe2 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -557,7 +557,7 @@ static int print_results_bw(char *filename,  int bm_pid, float bw_imc,
 	return 0;
 }
 
-static void set_cmt_path(const char *ctrlgrp, const char *mongrp, char sock_num)
+void set_cmt_path(const char *ctrlgrp, const char *mongrp, char sock_num)
 {
 	if (strlen(ctrlgrp) && strlen(mongrp))
 		sprintf(llc_occup_path,	CON_MON_LCC_OCCUP_PATH,	RESCTRL_PATH,
@@ -698,8 +698,8 @@ int resctrl_val(const struct resctrl_test *test,
 {
 	char *resctrl_val = param->resctrl_val;
 	unsigned long bw_resc_start = 0;
+	int res_id, ret = 0, pipefd[2];
 	struct sigaction sigact;
-	int ret = 0, pipefd[2];
 	char pipe_message = 0;
 	union sigval value;
 
@@ -828,6 +828,8 @@ int resctrl_val(const struct resctrl_test *test,
 	sleep(1);
 
 	/* Test runs until the callback setup() tells the test to stop. */
+	get_domain_id("L3", uparams->cpu, &res_id);
+	res_id *= snc_ways();
 	while (1) {
 		ret = param->setup(test, uparams, param);
 		if (ret == END_OF_TESTS) {
@@ -844,7 +846,8 @@ int resctrl_val(const struct resctrl_test *test,
 				break;
 		} else if (!strncmp(resctrl_val, CMT_STR, sizeof(CMT_STR))) {
 			sleep(1);
-			ret = measure_llc_resctrl(param->filename, bm_pid);
+			ret = measure_llc_resctrl(param->filename, bm_pid, param->ctrlgrp,
+						  param->mongrp, res_id);
 			if (ret)
 				break;
 		}
-- 
2.44.0