tests: settings: Performance test for settings

This adds a on target performance test for Settings SS. Using this test
performance of the Setting SS + NVS/ZMS backend can be benchmarked.

The test repeatedly write 128 settings entries. Each setting entry
has a size of 4 bytes, and path length of 16 bytes (excluding the
null-terminator).

The test has two variants, with and without Bluetooth scan running.
This is useful to benchmark performance along with some component
of BT subsystem activated.

The test could be enhanced in future to include or create combinations
of different functionalities running, when agreesive store operations
are happening.

Signed-off-by: Omkar Kulkarni <omkar.kulkarni@nordicsemi.no>

tests/subsys/settings/performance/CMakeLists.txt

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(test_settings_perf)
+
+zephyr_include_directories(
+	${ZEPHYR_BASE}/subsys/settings/include
+	${ZEPHYR_BASE}/subsys/settings/src
+	)
+
+target_sources(app PRIVATE
+	settings_test_perf.c)

tests/subsys/settings/performance/prj.conf

@@ -0,0 +1,7 @@
+CONFIG_ZTEST=y
+CONFIG_FLASH=y
+CONFIG_FLASH_MAP=y
+CONFIG_ZMS=y
+
+CONFIG_SETTINGS=y
+CONFIG_SETTINGS_RUNTIME=y

tests/subsys/settings/performance/settings_test_perf.c

@@ -0,0 +1,133 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <stdlib.h>
+
+#include "settings_priv.h"
+#include <zephyr/ztest.h>
+#include <zephyr/settings/settings.h>
+#include <zephyr/bluetooth/bluetooth.h>
+
+/* This is a test suite for performance testing of settings subsystem by writing
+ * many small setting values repeatedly. Ideally, this should consume as small
+ * amount of time as possible for best possible UX.
+ */
+
+static struct k_work_q settings_work_q;
+static K_THREAD_STACK_DEFINE(settings_work_stack, 2024);
+static struct k_work_delayable pending_store;
+
+#define TEST_SETTINGS_COUNT (128)
+#define TEST_STORE_ITR (5)
+#define TEST_TIMEOUT_SEC (60)
+#define TEST_SETTINGS_WORKQ_PRIO (1)
+
+static void bt_scan_cb(const bt_addr_le_t *addr, int8_t rssi, uint8_t adv_type,
+		struct net_buf_simple *buf)
+{
+	printk("len %u\n", buf->len);
+}
+
+struct test_setting {
+	uint32_t val;
+} test_settings[TEST_SETTINGS_COUNT];
+
+K_SEM_DEFINE(waitfor_work, 0, 1);
+
+static void store_pending(struct k_work *work)
+{
+	int err;
+	char path[20];
+	struct test_stats {
+		uint32_t total_calculated;
+		uint32_t total_measured;
+		uint32_t single_entry_max;
+		uint32_t single_entry_min;
+	} stats = {0, 0, 0, UINT32_MAX};
+
+	int64_t ts1 = k_uptime_get();
+
+	/* benchmark storage performance */
+	for (int j = 0; j < TEST_STORE_ITR; j++) {
+		for (int i = 0; i < TEST_SETTINGS_COUNT; i++) {
+			test_settings[i].val = TEST_SETTINGS_COUNT*j + i;
+
+			int64_t ts2 = k_uptime_get();
+
+			snprintk(path, sizeof(path), "ab/cdef/ghi/%04x", i);
+			err = settings_save_one(path, &test_settings[i],
+						sizeof(struct test_setting));
+			zassert_equal(err, 0, "settings_save_one failed %d", err);
+
+			int64_t delta2 = k_uptime_delta(&ts2);
+
+			if (stats.single_entry_max < delta2) {
+				stats.single_entry_max = delta2;
+			}
+			if (stats.single_entry_min > delta2) {
+				stats.single_entry_min = delta2;
+			}
+			stats.total_calculated += delta2;
+		}
+	}
+
+	int64_t delta1 = k_uptime_delta(&ts1);
+
+	stats.total_measured = delta1;
+
+	printk("*** storing of %u entries completed ***\n", ARRAY_SIZE(test_settings));
+	printk("total calculated: %u, total measured: %u\n", stats.total_calculated,
+	       stats.total_measured);
+	printk("entry max: %u, entry min: %u\n", stats.single_entry_max,
+	       stats.single_entry_min);
+
+	k_sem_give(&waitfor_work);
+}
+
+ZTEST_SUITE(settings_perf, NULL, NULL, NULL, NULL, NULL);
+
+ZTEST(settings_perf, test_performance)
+{
+	int err;
+
+	if (IS_ENABLED(CONFIG_NVS)) {
+		printk("Testing with NVS\n");
+	} else if (IS_ENABLED(CONFIG_ZMS)) {
+		printk("Testing with ZMS\n");
+	}
+
+	k_work_queue_start(&settings_work_q, settings_work_stack,
+		K_THREAD_STACK_SIZEOF(settings_work_stack),
+		K_PRIO_COOP(TEST_SETTINGS_WORKQ_PRIO), NULL);
+	k_thread_name_set(&settings_work_q.thread, "Settings workq");
+	k_work_init_delayable(&pending_store, store_pending);
+
+	if (IS_ENABLED(CONFIG_BT)) {
+		/* enable one of the major subsystems, and start scanning. */
+		err = bt_enable(NULL);
+		zassert_equal(err, 0, "Bluetooth init failed (err %d)\n", err);
+
+		err = bt_le_scan_start(BT_LE_SCAN_ACTIVE, bt_scan_cb);
+		zassert_equal(err, 0, "Scanning failed to start (err %d)\n", err);
+	}
+
+	err = settings_subsys_init();
+	zassert_equal(err, 0, "settings_backend_init failed %d", err);
+
+	/* fill with values */
+	for (int i = 0; i < TEST_SETTINGS_COUNT; i++) {
+		test_settings[i].val = i;
+	}
+
+	k_work_reschedule_for_queue(&settings_work_q, &pending_store, K_NO_WAIT);
+
+	err = k_sem_take(&waitfor_work, K_SECONDS(TEST_TIMEOUT_SEC));
+	zassert_equal(err, 0, "k_sem_take failed %d", err);
+
+	if (IS_ENABLED(CONFIG_BT)) {
+		err = bt_le_scan_stop();
+		zassert_equal(err, 0, "Scanning failed to stop (err %d)\n", err);
+	}
+}

tests/subsys/settings/performance/testcase.yaml

@@ -0,0 +1,66 @@
+tests:
+  settings.performance.zms:
+    extra_configs:
+      - CONFIG_SETTINGS_ZMS=y
+      - CONFIG_ZMS_LOOKUP_CACHE=y
+      - CONFIG_ZMS_LOOKUP_CACHE_SIZE=512
+    platform_allow:
+      - nrf52840dk/nrf52840
+      - nrf54l15dk/nrf54l15/cpuapp
+    min_ram: 32
+    tags:
+      - settings
+      - zms
+
+  settings.performance.nvs:
+    extra_configs:
+      - CONFIG_ZMS=n
+      - CONFIG_NVS=y
+      - CONFIG_NVS_LOOKUP_CACHE=y
+      - CONFIG_NVS_LOOKUP_CACHE_SIZE=512
+      - CONFIG_SETTINGS_NVS_NAME_CACHE=y
+      - CONFIG_SETTINGS_NVS_NAME_CACHE_SIZE=512
+    platform_allow:
+      - nrf52840dk/nrf52840
+      - nrf54l15dk/nrf54l15/cpuapp
+    min_ram: 32
+    tags:
+      - settings
+      - nvs
+
+  settings.performance.zms_bt:
+    extra_configs:
+      - CONFIG_BT=y
+      - CONFIG_BT_OBSERVER=y
+      - CONFIG_BT_PERIPHERAL=y
+      - CONFIG_SETTINGS_ZMS=y
+      - CONFIG_ZMS_LOOKUP_CACHE=y
+      - CONFIG_ZMS_LOOKUP_CACHE_SIZE=512
+    platform_allow: nrf52840dk/nrf52840
+    platform_exclude:
+      - native_sim
+      - qemu_x86
+    min_ram: 32
+    tags:
+      - settings
+      - zms
+
+  settings.performance.nvs_bt:
+    extra_configs:
+      - CONFIG_BT=y
+      - CONFIG_BT_OBSERVER=y
+      - CONFIG_BT_PERIPHERAL=y
+      - CONFIG_ZMS=n
+      - CONFIG_NVS=y
+      - CONFIG_NVS_LOOKUP_CACHE=y
+      - CONFIG_NVS_LOOKUP_CACHE_SIZE=512
+      - CONFIG_SETTINGS_NVS_NAME_CACHE=y
+      - CONFIG_SETTINGS_NVS_NAME_CACHE_SIZE=512
+    platform_allow: nrf52840dk/nrf52840
+    platform_exclude:
+      - native_sim
+      - qemu_x86
+    min_ram: 32
+    tags:
+      - settings
+      - nvs