Re: [PATCH v4] Add power/gpu_frequency tracepoint.

Hi Peiyong,

On Mon, Nov 30, 2020 at 02:33:59PM -0800, Peiyong Lin wrote:

On Tue, Nov 17, 2020 at 1:31 PM Peiyong Lin lpy@google.com wrote:

...

On Thu, Oct 22, 2020 at 10:34 AM Peiyong Lin lpy@google.com wrote:

...

Historically there is no common trace event for GPU frequency, in downstream Android each different hardware vendor implements their own way to expose GPU frequency, for example as a debugfs node. This patch standardize it as a common trace event in upstream linux kernel to help the ecosystem have a common implementation across hardware vendors. Toolings in the Linux ecosystem will benefit from this especially in the downstream Android, where this information is critical to graphics developers.

Signed-off-by: Peiyong Lin lpy@google.com

Changelog since v3:

• Correct copyright title.

Changelog since v2:

• Add more comments to indicate when the event should be emitted.
• Change state to frequency.

Changelog since v1:

• Use %u in TP_printk

drivers/gpu/Makefile | 1 + drivers/gpu/trace/Kconfig | 3 +++ drivers/gpu/trace/Makefile | 1 + drivers/gpu/trace/trace_gpu_frequency.c | 13 ++++++++++ include/trace/events/power.h | 33 +++++++++++++++++++++++++ 5 files changed, 51 insertions(+) create mode 100644 drivers/gpu/trace/trace_gpu_frequency.c

diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile index 835c88318cec..f289a47eb031 100644 --- a/drivers/gpu/Makefile +++ b/drivers/gpu/Makefile @@ -6,3 +6,4 @@ obj-$(CONFIG_TEGRA_HOST1X) += host1x/ obj-y += drm/ vga/ obj-$(CONFIG_IMX_IPUV3_CORE) += ipu-v3/ obj-$(CONFIG_TRACE_GPU_MEM) += trace/ +obj-$(CONFIG_TRACE_GPU_FREQUENCY) += trace/ diff --git a/drivers/gpu/trace/Kconfig b/drivers/gpu/trace/Kconfig index c24e9edd022e..ac4aec8d5845 100644 --- a/drivers/gpu/trace/Kconfig +++ b/drivers/gpu/trace/Kconfig @@ -2,3 +2,6 @@

config TRACE_GPU_MEM bool

+config TRACE_GPU_FREQUENCY

•   bool
  

diff --git a/drivers/gpu/trace/Makefile b/drivers/gpu/trace/Makefile index b70fbdc5847f..2b7ae69327d6 100644 --- a/drivers/gpu/trace/Makefile +++ b/drivers/gpu/trace/Makefile @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_TRACE_GPU_MEM) += trace_gpu_mem.o +obj-$(CONFIG_TRACE_GPU_FREQUENCY) += trace_gpu_frequency.o diff --git a/drivers/gpu/trace/trace_gpu_frequency.c b/drivers/gpu/trace/trace_gpu_frequency.c new file mode 100644 index 000000000000..668fabd6b77a --- /dev/null +++ b/drivers/gpu/trace/trace_gpu_frequency.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • GPU frequency trace points
• • Copyright (C) 2020 Google LLC
• */

+#include <linux/module.h>

+#define CREATE_TRACE_POINTS +#include <trace/events/power.h>

+EXPORT_TRACEPOINT_SYMBOL(gpu_frequency); diff --git a/include/trace/events/power.h b/include/trace/events/power.h index af5018aa9517..343825a76953 100644 --- a/include/trace/events/power.h +++ b/include/trace/events/power.h @@ -500,6 +500,39 @@ DEFINE_EVENT(dev_pm_qos_request, dev_pm_qos_remove_request,

    TP_ARGS(name, type, new_value)

);

+/**

• • gpu_frequency - Reports the GPU frequency in GPU clock domains.
• • This event should be emitted whenever there's a GPU frequency change happens,
• • or a GPU goes from idle state to active state, or vice versa.
• • When the GPU goes from idle state to active state, this event should report
• • the GPU frequency of the active state. When the GPU goes from active state to
• • idle state, this event should report a zero frequency value.
• • @frequency: New frequency (in KHz)
• • @gpu_id: Id for each GPU clock domain

Thinking about options for how to assign this, there are a few existing tracepoints (I see block device and jb2) which use dev_t, so perhaps that would be an option. We'd still want to be able to expose multiple clocks per device though, either with a separate field or with a defined packing into this one.

dev_t is a little bit tricky because the packing can (is?) different between the kernel and C library. major + minor + clock domain as 3 separate fields would be the most explicit.

As the intended use-case is tools, I imagine userspace will want to link this to data exposed via other APIs, so gpu_id needs to somehow allow that. That probably means some opaque integer assigned within the kernel isn't OK.

Hopefully some other vendors have thoughts on what would work in their systems.

Thanks, -Brian

...

...

• */

+TRACE_EVENT(gpu_frequency,

•   TP_PROTO(unsigned int frequency, unsigned int gpu_id),
  

•   TP_ARGS(frequency, gpu_id),
  

•   TP_STRUCT__entry(
  

•           __field(unsigned int, frequency)
  

•           __field(unsigned int, gpu_id)
  

•   ),
  

•   TP_fast_assign(
  

•           __entry->frequency = frequency;
  

•           __entry->gpu_id = gpu_id;
  

•   ),
  

•   TP_printk("frequency=%u gpu_id=%u",
  

•           __entry->frequency, __entry->gpu_id)
  

+); #endif /* _TRACE_POWER_H */

/* This part must be outside protection */

2.29.0.rc1.297.gfa9743e501-goog

Hi there,

Per request, re-send this patch with dri-devel@ list CCed.

Thanks, Peiyong

Hi there,

For GPU drivers folks in dri-devel@ list, any input?

Thanks, Peiyong _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel