Re: [PATCH v5 2/6] drm/panfrost: Add fdinfo support GPU load metrics

2023-09-18 Thread Steven Price 
On 14/09/2023 23:38, Adrián Larumbe wrote:
> The drm-stats fdinfo tags made available to user space are drm-engine,
> drm-cycles, drm-max-freq and drm-curfreq, one per job slot.
> 
> This deviates from standard practice in other DRM drivers, where a single
> set of key:value pairs is provided for the whole render engine. However,
> Panfrost has separate queues for fragment and vertex/tiler jobs, so a
> decision was made to calculate bus cycles and workload times separately.
> 
> Maximum operating frequency is calculated at devfreq initialisation time.
> Current frequency is made available to user space because nvtop uses it
> when performing engine usage calculations.
> 
> It is important to bear in mind that both GPU cycle and kernel time numbers
> provided are at best rough estimations, and always reported in excess from
> the actual figure because of two reasons:
>  - Excess time because of the delay between the end of a job processing,
>the subsequent job IRQ and the actual time of the sample.
>  - Time spent in the engine queue waiting for the GPU to pick up the next
>job.
> 
> To avoid race conditions during enablement/disabling, a reference counting
> mechanism was introduced, and a job flag that tells us whether a given job
> increased the refcount. This is necessary, because user space can toggle
> cycle counting through a debugfs file, and a given job might have been in
> flight by the time cycle counting was disabled.
> 
> The main goal of the debugfs cycle counter knob is letting tools like nvtop
> or IGT's gputop switch it at any time, to avoid power waste in case no
> engine usage measuring is necessary.
> 
> Signed-off-by: Adrián Larumbe 
> Reviewed-by: Boris Brezillon 
> ---
>  drivers/gpu/drm/panfrost/Makefile   |  2 +
>  drivers/gpu/drm/panfrost/panfrost_debugfs.c | 20 
>  drivers/gpu/drm/panfrost/panfrost_debugfs.h | 13 +
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c |  8 +++
>  drivers/gpu/drm/panfrost/panfrost_devfreq.h |  3 ++
>  drivers/gpu/drm/panfrost/panfrost_device.c  |  2 +
>  drivers/gpu/drm/panfrost/panfrost_device.h  | 13 +
>  drivers/gpu/drm/panfrost/panfrost_drv.c | 57 -
>  drivers/gpu/drm/panfrost/panfrost_gpu.c | 41 +++
>  drivers/gpu/drm/panfrost/panfrost_gpu.h |  4 ++
>  drivers/gpu/drm/panfrost/panfrost_job.c | 24 +
>  drivers/gpu/drm/panfrost/panfrost_job.h |  5 ++
>  12 files changed, 191 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.c
>  create mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.h
> 
> diff --git a/drivers/gpu/drm/panfrost/Makefile 
> b/drivers/gpu/drm/panfrost/Makefile
> index 7da2b3f02ed9..2c01c1e7523e 100644
> --- a/drivers/gpu/drm/panfrost/Makefile
> +++ b/drivers/gpu/drm/panfrost/Makefile
> @@ -12,4 +12,6 @@ panfrost-y := \
>   panfrost_perfcnt.o \
>   panfrost_dump.o
>  
> +panfrost-$(CONFIG_DEBUG_FS) += panfrost_debugfs.o
> +
>  obj-$(CONFIG_DRM_PANFROST) += panfrost.o
> diff --git a/drivers/gpu/drm/panfrost/panfrost_debugfs.c 
> b/drivers/gpu/drm/panfrost/panfrost_debugfs.c
> new file mode 100644
> index ..cc14eccba206
> --- /dev/null
> +++ b/drivers/gpu/drm/panfrost/panfrost_debugfs.c
> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright 2023 Collabora ltd. */
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +#include "panfrost_device.h"
> +#include "panfrost_gpu.h"
> +#include "panfrost_debugfs.h"
> +
> +void panfrost_debugfs_init(struct drm_minor *minor)
> +{
> + struct drm_device *dev = minor->dev;
> + struct panfrost_device *pfdev = 
> platform_get_drvdata(to_platform_device(dev->dev));
> +
> + debugfs_create_atomic_t("profile", 0600, minor->debugfs_root, 
> >profile_mode);
> +}
> diff --git a/drivers/gpu/drm/panfrost/panfrost_debugfs.h 
> b/drivers/gpu/drm/panfrost/panfrost_debugfs.h
> new file mode 100644
> index ..db1c158bcf2f
> --- /dev/null
> +++ b/drivers/gpu/drm/panfrost/panfrost_debugfs.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright 2023 Collabora ltd.
> + */
> +
> +#ifndef PANFROST_DEBUGFS_H
> +#define PANFROST_DEBUGFS_H
> +
> +#ifdef CONFIG_DEBUG_FS
> +void panfrost_debugfs_init(struct drm_minor *minor);
> +#endif
> +
> +#endif  /* PANFROST_DEBUGFS_H */
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c 
> b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> index 58dfb15a8757..28caffc689e2 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> @@ -58,6 +58,7 @@ static int panfrost_devfreq_get_dev_status(struct device 
> *dev,
>   spin_lock_irqsave(>lock, irqflags);
>  
>   panfrost_devfreq_update_utilization(pfdevfreq);
> + pfdevfreq->current_frequency = status->current_frequency;
>  
>   status->total_time = ktime_to_ns(ktime_add(pfdevfreq->busy_time,
>

[PATCH v5 2/6] drm/panfrost: Add fdinfo support GPU load metrics

2023-09-14 Thread Adrián Larumbe 
The drm-stats fdinfo tags made available to user space are drm-engine,
drm-cycles, drm-max-freq and drm-curfreq, one per job slot.

This deviates from standard practice in other DRM drivers, where a single
set of key:value pairs is provided for the whole render engine. However,
Panfrost has separate queues for fragment and vertex/tiler jobs, so a
decision was made to calculate bus cycles and workload times separately.

Maximum operating frequency is calculated at devfreq initialisation time.
Current frequency is made available to user space because nvtop uses it
when performing engine usage calculations.

It is important to bear in mind that both GPU cycle and kernel time numbers
provided are at best rough estimations, and always reported in excess from
the actual figure because of two reasons:
 - Excess time because of the delay between the end of a job processing,
   the subsequent job IRQ and the actual time of the sample.
 - Time spent in the engine queue waiting for the GPU to pick up the next
   job.

To avoid race conditions during enablement/disabling, a reference counting
mechanism was introduced, and a job flag that tells us whether a given job
increased the refcount. This is necessary, because user space can toggle
cycle counting through a debugfs file, and a given job might have been in
flight by the time cycle counting was disabled.

The main goal of the debugfs cycle counter knob is letting tools like nvtop
or IGT's gputop switch it at any time, to avoid power waste in case no
engine usage measuring is necessary.

Signed-off-by: Adrián Larumbe 
Reviewed-by: Boris Brezillon 
---
 drivers/gpu/drm/panfrost/Makefile   |  2 +
 drivers/gpu/drm/panfrost/panfrost_debugfs.c | 20 
 drivers/gpu/drm/panfrost/panfrost_debugfs.h | 13 +
 drivers/gpu/drm/panfrost/panfrost_devfreq.c |  8 +++
 drivers/gpu/drm/panfrost/panfrost_devfreq.h |  3 ++
 drivers/gpu/drm/panfrost/panfrost_device.c  |  2 +
 drivers/gpu/drm/panfrost/panfrost_device.h  | 13 +
 drivers/gpu/drm/panfrost/panfrost_drv.c | 57 -
 drivers/gpu/drm/panfrost/panfrost_gpu.c | 41 +++
 drivers/gpu/drm/panfrost/panfrost_gpu.h |  4 ++
 drivers/gpu/drm/panfrost/panfrost_job.c | 24 +
 drivers/gpu/drm/panfrost/panfrost_job.h |  5 ++
 12 files changed, 191 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.c
 create mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.h

diff --git a/drivers/gpu/drm/panfrost/Makefile 
b/drivers/gpu/drm/panfrost/Makefile
index 7da2b3f02ed9..2c01c1e7523e 100644
--- a/drivers/gpu/drm/panfrost/Makefile
+++ b/drivers/gpu/drm/panfrost/Makefile
@@ -12,4 +12,6 @@ panfrost-y := \
panfrost_perfcnt.o \
panfrost_dump.o
 
+panfrost-$(CONFIG_DEBUG_FS) += panfrost_debugfs.o
+
 obj-$(CONFIG_DRM_PANFROST) += panfrost.o
diff --git a/drivers/gpu/drm/panfrost/panfrost_debugfs.c 
b/drivers/gpu/drm/panfrost/panfrost_debugfs.c
new file mode 100644
index ..cc14eccba206
--- /dev/null
+++ b/drivers/gpu/drm/panfrost/panfrost_debugfs.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2023 Collabora ltd. */
+
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#include "panfrost_device.h"
+#include "panfrost_gpu.h"
+#include "panfrost_debugfs.h"
+
+void panfrost_debugfs_init(struct drm_minor *minor)
+{
+   struct drm_device *dev = minor->dev;
+   struct panfrost_device *pfdev = 
platform_get_drvdata(to_platform_device(dev->dev));
+
+   debugfs_create_atomic_t("profile", 0600, minor->debugfs_root, 
>profile_mode);
+}
diff --git a/drivers/gpu/drm/panfrost/panfrost_debugfs.h 
b/drivers/gpu/drm/panfrost/panfrost_debugfs.h
new file mode 100644
index ..db1c158bcf2f
--- /dev/null
+++ b/drivers/gpu/drm/panfrost/panfrost_debugfs.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2023 Collabora ltd.
+ */
+
+#ifndef PANFROST_DEBUGFS_H
+#define PANFROST_DEBUGFS_H
+
+#ifdef CONFIG_DEBUG_FS
+void panfrost_debugfs_init(struct drm_minor *minor);
+#endif
+
+#endif  /* PANFROST_DEBUGFS_H */
diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c 
b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
index 58dfb15a8757..28caffc689e2 100644
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
@@ -58,6 +58,7 @@ static int panfrost_devfreq_get_dev_status(struct device *dev,
spin_lock_irqsave(>lock, irqflags);
 
panfrost_devfreq_update_utilization(pfdevfreq);
+   pfdevfreq->current_frequency = status->current_frequency;
 
status->total_time = ktime_to_ns(ktime_add(pfdevfreq->busy_time,
   pfdevfreq->idle_time));
@@ -117,6 +118,7 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
struct devfreq *devfreq;
struct thermal_cooling_device *cooling;
struct panfrost_devfreq *pfdevfreq = >pfdevfreq;
+