profiling: Add perf tool

Add profiling subsystem.

Add perf util based on periodic stack unwinding. Perf from Linux
was taken as a reference.

The operation of module is based on frame pointer usage and saving
registers during interruption handling.
The unwinding function stay in timer as expiry functioin so is called
during interruption handling. Thus the function have access to saved
registers (program counter and frame pointer in particular) of the current
thread and use it to unwind the thread stack.
Timer starting and results printing function are made as shell commands
for conveniency.

Originally-by: Yonatan Goldschmidt <[email protected]>
Signed-off-by: Mikhail Kushnerov <[email protected]>

Author: Mikhail Kushnerov

subsys/CMakeLists.txt

@@ -48,6 +48,7 @@ add_subdirectory_ifdef(CONFIG_JWT jwt)
 add_subdirectory_ifdef(CONFIG_LLEXT llext)
 add_subdirectory_ifdef(CONFIG_MODEM_MODULES modem)
 add_subdirectory_ifdef(CONFIG_NET_BUF net)
+add_subdirectory_ifdef(CONFIG_PROFILING profiling)
 add_subdirectory_ifdef(CONFIG_RETENTION retention)
 add_subdirectory_ifdef(CONFIG_SENSING sensing)
 add_subdirectory_ifdef(CONFIG_SETTINGS settings)

subsys/Kconfig

@@ -33,6 +33,7 @@ source "subsys/modem/Kconfig"
 source "subsys/net/Kconfig"
 source "subsys/pm/Kconfig"
 source "subsys/portability/Kconfig"
+source "subsys/profiling/Kconfig"
 source "subsys/random/Kconfig"
 source "subsys/retention/Kconfig"
 source "subsys/rtio/Kconfig"

subsys/profiling/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Copyright (c) 2023 KNS Group LLC (YADRO)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory_ifdef(CONFIG_PROFILING_PERF perf)

subsys/profiling/Kconfig

@@ -0,0 +1,14 @@
+# Copyright (c) 2023 KNS Group LLC (YADRO)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig PROFILING
+	bool "Profiling tools"
+	help
+	  Enable profiling tools, such as perf
+
+if PROFILING
+
+source "subsys/profiling/perf/Kconfig"
+
+endif

subsys/profiling/perf/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Copyright (c) 2023 KNS Group LLC (YADRO)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_sources(perf.c)

subsys/profiling/perf/Kconfig

@@ -0,0 +1,23 @@
+# Copyright (c) 2023 KNS Group LLC (YADRO)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config PROFILING_PERF
+	bool "Perf support"
+	depends on THREAD_STACK_INFO
+	depends on !SMP
+	depends on FRAME_POINTER
+	depends on SHELL
+	depends on RISCV || X86
+	help
+	  Enable perf shell command.
+
+if PROFILING_PERF
+
+config PROFILING_PERF_BUFFER_SIZE
+	int "Perf buffer size"
+	default 2048
+	help
+	  Size of buffer, that used by perf to save samples from stack tracing.
+
+endif

subsys/profiling/perf/perf.c

@@ -0,0 +1,145 @@
+/*
+ *  Copyright (c) 2023 KNS Group LLC (YADRO)
+ *  Copyright (c) 2020 Yonatan Goldschmidt <[email protected]>
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/init.h>
+#include <zephyr/arch/cpu.h>
+#include <zephyr/shell/shell.h>
+#include <zephyr/shell/shell_uart.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+size_t arch_perf_current_stack_trace(uintptr_t *buf, size_t size);
+
+struct perf_data_t {
+	struct k_timer timer;
+
+	const struct shell *sh;
+
+	struct k_work_delayable dwork;
+
+	size_t idx;
+	uintptr_t buf[CONFIG_PROFILING_PERF_BUFFER_SIZE];
+	bool buf_full;
+};
+
+#define PERF_EVENT_TRACING_BUF_OVERFLOW (1 << 0)
+
+static struct perf_data_t perf_data = {
+	.idx = 0,
+};
+
+static void perf_tracer(struct k_timer *timer)
+{
+	struct perf_data_t *perf_data_ptr =
+		(struct perf_data_t *)k_timer_user_data_get(timer);
+
+	size_t trace_length = 0;
+
+	if (++perf_data_ptr->idx < CONFIG_PROFILING_PERF_BUFFER_SIZE) {
+		trace_length = arch_perf_current_stack_trace(
+					perf_data_ptr->buf + perf_data_ptr->idx,
+					CONFIG_PROFILING_PERF_BUFFER_SIZE - perf_data_ptr->idx);
+	}
+
+	if (trace_length != 0) {
+		perf_data_ptr->buf[perf_data_ptr->idx - 1] = trace_length;
+		perf_data_ptr->idx += trace_length;
+	} else {
+		--perf_data_ptr->idx;
+		perf_data_ptr->buf_full = true;
+		k_timer_stop(timer);
+		k_work_reschedule(&perf_data_ptr->dwork, K_NO_WAIT);
+	}
+}
+
+static void perf_dwork_handler(struct k_work *work)
+{
+	struct k_work_delayable *dwork = k_work_delayable_from_work(work);
+	struct perf_data_t *perf_data_ptr = CONTAINER_OF(dwork, struct perf_data_t, dwork);
+
+	if (perf_data_ptr->buf_full) {
+		shell_error(perf_data_ptr->sh, "Perf buf overflow!");
+	} else {
+		k_timer_stop(&perf_data_ptr->timer);
+		shell_print(perf_data_ptr->sh, "Perf done!");
+	}
+}
+
+static int perf_init(void)
+{
+	k_timer_init(&perf_data.timer, perf_tracer, NULL);
+	k_work_init_delayable(&perf_data.dwork, perf_dwork_handler);
+
+	return 0;
+}
+
+int cmd_perf_record(const struct shell *sh, size_t argc, char **argv)
+{
+	if (k_work_delayable_is_pending(&perf_data.dwork)) {
+		shell_warn(sh, "Perf is already running");
+		return -EINPROGRESS;
+	}
+
+	if (perf_data.buf_full) {
+		shell_warn(sh, "Perf buffer is full");
+		return -ENOBUFS;
+	}
+
+	k_timeout_t duration = K_MSEC(strtoll(argv[1], NULL, 10));
+	k_timeout_t period = K_NSEC(1000000000 / strtoll(argv[2], NULL, 10));
+
+	perf_data.sh = sh;
+
+	k_timer_user_data_set(&perf_data.timer, &perf_data);
+	k_timer_start(&perf_data.timer, K_NO_WAIT, period);
+
+	k_work_schedule(&perf_data.dwork, duration);
+
+	shell_print(sh, "Enabled perf");
+
+	return 0;
+}
+
+int cmd_perf_print(const struct shell *sh, size_t argc, char **argv)
+{
+	if (k_work_delayable_is_pending(&perf_data.dwork)) {
+		shell_warn(sh, "Perf is already running");
+		return -EINPROGRESS;
+	}
+
+	shell_print(sh, "Perf buf length %zu", perf_data.idx);
+	for (size_t i = 0; i < perf_data.idx; i++) {
+		shell_print(sh, "%016lx", perf_data.buf[i]);
+	}
+
+	perf_data.idx = 0;
+
+	return 0;
+}
+
+static int cmd_perf(const struct shell *sh, size_t argc, char **argv)
+{
+	ARG_UNUSED(argc);
+	ARG_UNUSED(argv);
+
+	shell_print(sh, "perfy");
+	return 0;
+}
+
+#define CMD_HELP_RECORD										\
+	"Start recording for <duration> ms on <frequency> Hz\n"	\
+	"Usage: record <duration> <frequency>\n"
+
+SHELL_STATIC_SUBCMD_SET_CREATE(m_sub_perf,
+	SHELL_CMD_ARG(record, NULL, CMD_HELP_RECORD, cmd_perf_record, 3, 0),
+	SHELL_CMD_ARG(printbuf, NULL, "Print the perf buffer", cmd_perf_print, 0, 0),
+	SHELL_SUBCMD_SET_END
+);
+SHELL_CMD_ARG_REGISTER(perf, &m_sub_perf, "Perf!", cmd_perf, 0, 0);
+
+SYS_INIT(perf_init, APPLICATION, 0);