On Fri, Dec 17, 2021 at 02:12:41AM +0800, Rafael J. Wysocki wrote:

On Tue, Nov 30, 2021 at 1:38 PM Huang Rui [off-list ref] wrote:

quoted

Add trace event to monitor the performance value changes which is
controlled by cpu governors.

This would need an ACK from Steve.

quoted

Signed-off-by: Huang Rui <ray.huang@amd.com>
---
 drivers/cpufreq/Makefile           |  6 ++-
 drivers/cpufreq/amd-pstate-trace.c |  2 +
 drivers/cpufreq/amd-pstate-trace.h | 77 ++++++++++++++++++++++++++++++

Why are these two extra files necessary?

Please see below answer.

quoted

 drivers/cpufreq/amd-pstate.c       |  4 ++
 4 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 drivers/cpufreq/amd-pstate-trace.c
 create mode 100644 drivers/cpufreq/amd-pstate-trace.h

diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index c8d307010922..285de70af877 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile

@@ -17,6 +17,10 @@ obj-$(CONFIG_CPU_FREQ_GOV_ATTR_SET)  += cpufreq_governor_attr_set.o
 obj-$(CONFIG_CPUFREQ_DT)               += cpufreq-dt.o
 obj-$(CONFIG_CPUFREQ_DT_PLATDEV)       += cpufreq-dt-platdev.o

+# Traces
+CFLAGS_amd-pstate-trace.o               := -I$(src)
+amd_pstate-y                           := amd-pstate.o amd-pstate-trace.o
+
 ##################################################################################
 # x86 drivers.
 # Link order matters. K8 is preferred to ACPI because of firmware bugs in early

@@ -25,7 +29,7 @@ obj-$(CONFIG_CPUFREQ_DT_PLATDEV)      += cpufreq-dt-platdev.o
 # speedstep-* is preferred over p4-clockmod.

 obj-$(CONFIG_X86_ACPI_CPUFREQ)         += acpi-cpufreq.o
-obj-$(CONFIG_X86_AMD_PSTATE)           += amd-pstate.o
+obj-$(CONFIG_X86_AMD_PSTATE)           += amd_pstate.o
 obj-$(CONFIG_X86_POWERNOW_K8)          += powernow-k8.o
 obj-$(CONFIG_X86_PCC_CPUFREQ)          += pcc-cpufreq.o
 obj-$(CONFIG_X86_POWERNOW_K6)          += powernow-k6.o

diff --git a/drivers/cpufreq/amd-pstate-trace.c b/drivers/cpufreq/amd-pstate-trace.c
new file mode 100644
index 000000000000..891b696dcd69
--- /dev/null
+++ b/drivers/cpufreq/amd-pstate-trace.c

@@ -0,0 +1,2 @@
+#define CREATE_TRACE_POINTS
+#include "amd-pstate-trace.h"

diff --git a/drivers/cpufreq/amd-pstate-trace.h b/drivers/cpufreq/amd-pstate-trace.h
new file mode 100644
index 000000000000..647505957d4f
--- /dev/null
+++ b/drivers/cpufreq/amd-pstate-trace.h

@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * amd-pstate-trace.h - AMD Processor P-state Frequency Driver Tracer
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc. All Rights Reserved.
+ *
+ * Author: Huang Rui <ray.huang@amd.com>
+ */
+
+#if !defined(_AMD_PSTATE_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _AMD_PSTATE_TRACE_H
+
+#include <linux/cpufreq.h>
+#include <linux/tracepoint.h>
+#include <linux/trace_events.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM amd_cpu
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE amd-pstate-trace
+
+#define TPS(x)  tracepoint_string(x)
+
+TRACE_EVENT(amd_pstate_perf,

Could this be added to include/trace/events/power.h ?

Actually, that is my original idea, but once I move the trace into
include/trace/events/power.h, the amd-pstate driver cannot build as "ko"
anymore. This is the early stage, "ko" is friendly and flexible for us to
switch and compare between amd-pstate and acpi-cpufreq. I can move it into
"power" trace events once we address the performance issue on shared memory
solution.

Thanks,
Ray