[PATCH v6 2/6] drm/panfrost: Add fdinfo support GPU load metrics
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Wed Sep 20 15:40:47 UTC 2023
On 20/09/2023 00:34, 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 <adrian.larumbe at collabora.com>
> Reviewed-by: Boris Brezillon <boris.brezillon at collabora.com>
> Reviewed-by: Steven Price <steven.price at arm.com>
> ---
> 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 000000000000..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 <linux/debugfs.h>
> +#include <linux/platform_device.h>
> +#include <drm/drm_debugfs.h>
> +#include <drm/drm_file.h>
> +#include <drm/panfrost_drm.h>
> +
> +#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, &pfdev->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 000000000000..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(&pfdevfreq->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 = &pfdev->pfdevfreq;
> + unsigned long freq = ULONG_MAX;
>
> if (pfdev->comp->num_supplies > 1) {
> /*
> @@ -172,6 +174,12 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
> return ret;
> }
>
> + /* Find the fastest defined rate */
> + opp = dev_pm_opp_find_freq_floor(dev, &freq);
> + if (IS_ERR(opp))
> + return PTR_ERR(opp);
> + pfdevfreq->fast_rate = freq;
> +
> dev_pm_opp_put(opp);
>
> /*
> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.h b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> index 1514c1f9d91c..48dbe185f206 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> @@ -19,6 +19,9 @@ struct panfrost_devfreq {
> struct devfreq_simple_ondemand_data gov_data;
> bool opp_of_table_added;
>
> + unsigned long current_frequency;
> + unsigned long fast_rate;
> +
> ktime_t busy_time;
> ktime_t idle_time;
> ktime_t time_last_update;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> index fa1a086a862b..28f7046e1b1a 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_device.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_device.c
> @@ -207,6 +207,8 @@ int panfrost_device_init(struct panfrost_device *pfdev)
>
> spin_lock_init(&pfdev->as_lock);
>
> + spin_lock_init(&pfdev->cycle_counter.lock);
> +
> err = panfrost_clk_init(pfdev);
> if (err) {
> dev_err(pfdev->dev, "clk init failed %d\n", err);
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> index b0126b9fbadc..1e85656dc2f7 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> @@ -107,6 +107,7 @@ struct panfrost_device {
> struct list_head scheduled_jobs;
>
> struct panfrost_perfcnt *perfcnt;
> + atomic_t profile_mode;
>
> struct mutex sched_lock;
>
> @@ -121,6 +122,11 @@ struct panfrost_device {
> struct shrinker shrinker;
>
> struct panfrost_devfreq pfdevfreq;
> +
> + struct {
> + atomic_t use_count;
> + spinlock_t lock;
> + } cycle_counter;
> };
>
> struct panfrost_mmu {
> @@ -135,12 +141,19 @@ struct panfrost_mmu {
> struct list_head list;
> };
>
> +struct panfrost_engine_usage {
> + unsigned long long elapsed_ns[NUM_JOB_SLOTS];
> + unsigned long long cycles[NUM_JOB_SLOTS];
> +};
> +
> struct panfrost_file_priv {
> struct panfrost_device *pfdev;
>
> struct drm_sched_entity sched_entity[NUM_JOB_SLOTS];
>
> struct panfrost_mmu *mmu;
> +
> + struct panfrost_engine_usage engine_usage;
> };
>
> static inline struct panfrost_device *to_panfrost_device(struct drm_device *ddev)
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index a2ab99698ca8..3c93a11deab1 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -20,6 +20,7 @@
> #include "panfrost_job.h"
> #include "panfrost_gpu.h"
> #include "panfrost_perfcnt.h"
> +#include "panfrost_debugfs.h"
>
> static bool unstable_ioctls;
> module_param_unsafe(unstable_ioctls, bool, 0600);
> @@ -267,6 +268,7 @@ static int panfrost_ioctl_submit(struct drm_device *dev, void *data,
> job->requirements = args->requirements;
> job->flush_id = panfrost_gpu_get_latest_flush_id(pfdev);
> job->mmu = file_priv->mmu;
> + job->engine_usage = &file_priv->engine_usage;
>
> slot = panfrost_job_get_slot(job);
>
> @@ -523,7 +525,55 @@ static const struct drm_ioctl_desc panfrost_drm_driver_ioctls[] = {
> PANFROST_IOCTL(MADVISE, madvise, DRM_RENDER_ALLOW),
> };
>
> -DEFINE_DRM_GEM_FOPS(panfrost_drm_driver_fops);
> +
> +static void panfrost_gpu_show_fdinfo(struct panfrost_device *pfdev,
> + struct panfrost_file_priv *panfrost_priv,
> + struct drm_printer *p)
> +{
> + int i;
> +
> + /*
> + * IMPORTANT NOTE: drm-cycles and drm-engine measurements are not
> + * accurate, as they only provide a rough estimation of the number of
> + * GPU cycles and CPU time spent in a given context. This is due to two
> + * different factors:
> + * - Firstly, we must consider the time the CPU and then the kernel
> + * takes to process the GPU interrupt, which means additional time and
> + * GPU cycles will be added in excess to the real figure.
> + * - Secondly, the pipelining done by the Job Manager (2 job slots per
> + * engine) implies there is no way to know exactly how much time each
> + * job spent on the GPU.
> + */
> +
> + static const char * const engine_names[] = {
> + "fragment", "vertex-tiler", "compute-only"
> + };
> +
> + for (i = 0; i < NUM_JOB_SLOTS - 1; i++) {
FWIW you could future proof this a bit by using "i <
ARRAY_SIZE(engine_names)" and avoid maybe silent out of bounds reads if
someone updates NUM_JOB_SLOTS and forgets about this loop. Or stick a
warning of some sort.
> + drm_printf(p, "drm-engine-%s:\t%llu ns\n",
> + engine_names[i], panfrost_priv->engine_usage.elapsed_ns[i]);
> + drm_printf(p, "drm-cycles-%s:\t%llu\n",
> + engine_names[i], panfrost_priv->engine_usage.cycles[i]);
> + drm_printf(p, "drm-maxfreq-%s:\t%lu Hz\n",
> + engine_names[i], pfdev->pfdevfreq.fast_rate);
> + drm_printf(p, "drm-curfreq-%s:\t%lu Hz\n",
> + engine_names[i], pfdev->pfdevfreq.current_frequency);
I envisaged a link to driver specific docs at the bottom of
drm-usage-stats.rst so it would be nice if drivers would be adding those
sections and describing their private keys, engine names etc. ;)
Regards,
Tvrtko
> + }
> +}
> +
> +static void panfrost_show_fdinfo(struct drm_printer *p, struct drm_file *file)
> +{
> + struct drm_device *dev = file->minor->dev;
> + struct panfrost_device *pfdev = dev->dev_private;
> +
> + panfrost_gpu_show_fdinfo(pfdev, file->driver_priv, p);
> +}
> +
> +static const struct file_operations panfrost_drm_driver_fops = {
> + .owner = THIS_MODULE,
> + DRM_GEM_FOPS,
> + .show_fdinfo = drm_show_fdinfo,
> +};
>
> /*
> * Panfrost driver version:
> @@ -535,6 +585,7 @@ static const struct drm_driver panfrost_drm_driver = {
> .driver_features = DRIVER_RENDER | DRIVER_GEM | DRIVER_SYNCOBJ,
> .open = panfrost_open,
> .postclose = panfrost_postclose,
> + .show_fdinfo = panfrost_show_fdinfo,
> .ioctls = panfrost_drm_driver_ioctls,
> .num_ioctls = ARRAY_SIZE(panfrost_drm_driver_ioctls),
> .fops = &panfrost_drm_driver_fops,
> @@ -546,6 +597,10 @@ static const struct drm_driver panfrost_drm_driver = {
>
> .gem_create_object = panfrost_gem_create_object,
> .gem_prime_import_sg_table = panfrost_gem_prime_import_sg_table,
> +
> +#ifdef CONFIG_DEBUG_FS
> + .debugfs_init = panfrost_debugfs_init,
> +#endif
> };
>
> static int panfrost_probe(struct platform_device *pdev)
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> index 2faa344d89ee..f0be7e19b13e 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> @@ -73,6 +73,13 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev)
> gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_MASK_ALL);
> gpu_write(pfdev, GPU_INT_MASK, GPU_IRQ_MASK_ALL);
>
> + /*
> + * All in-flight jobs should have released their cycle
> + * counter references upon reset, but let us make sure
> + */
> + if (drm_WARN_ON(pfdev->ddev, atomic_read(&pfdev->cycle_counter.use_count) != 0))
> + atomic_set(&pfdev->cycle_counter.use_count, 0);
> +
> return 0;
> }
>
> @@ -321,6 +328,40 @@ static void panfrost_gpu_init_features(struct panfrost_device *pfdev)
> pfdev->features.shader_present, pfdev->features.l2_present);
> }
>
> +void panfrost_cycle_counter_get(struct panfrost_device *pfdev)
> +{
> + if (atomic_inc_not_zero(&pfdev->cycle_counter.use_count))
> + return;
> +
> + spin_lock(&pfdev->cycle_counter.lock);
> + if (atomic_inc_return(&pfdev->cycle_counter.use_count) == 1)
> + gpu_write(pfdev, GPU_CMD, GPU_CMD_CYCLE_COUNT_START);
> + spin_unlock(&pfdev->cycle_counter.lock);
> +}
> +
> +void panfrost_cycle_counter_put(struct panfrost_device *pfdev)
> +{
> + if (atomic_add_unless(&pfdev->cycle_counter.use_count, -1, 1))
> + return;
> +
> + spin_lock(&pfdev->cycle_counter.lock);
> + if (atomic_dec_return(&pfdev->cycle_counter.use_count) == 0)
> + gpu_write(pfdev, GPU_CMD, GPU_CMD_CYCLE_COUNT_STOP);
> + spin_unlock(&pfdev->cycle_counter.lock);
> +}
> +
> +unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev)
> +{
> + u32 hi, lo;
> +
> + do {
> + hi = gpu_read(pfdev, GPU_CYCLE_COUNT_HI);
> + lo = gpu_read(pfdev, GPU_CYCLE_COUNT_LO);
> + } while (hi != gpu_read(pfdev, GPU_CYCLE_COUNT_HI));
> +
> + return ((u64)hi << 32) | lo;
> +}
> +
> void panfrost_gpu_power_on(struct panfrost_device *pfdev)
> {
> int ret;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.h b/drivers/gpu/drm/panfrost/panfrost_gpu.h
> index 468c51e7e46d..876fdad9f721 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.h
> @@ -16,6 +16,10 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev);
> void panfrost_gpu_power_on(struct panfrost_device *pfdev);
> void panfrost_gpu_power_off(struct panfrost_device *pfdev);
>
> +void panfrost_cycle_counter_get(struct panfrost_device *pfdev);
> +void panfrost_cycle_counter_put(struct panfrost_device *pfdev);
> +unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev);
> +
> void panfrost_gpu_amlogic_quirk(struct panfrost_device *pfdev);
>
> #endif
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index 033f5e684707..fb16de2d0420 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -159,6 +159,16 @@ panfrost_dequeue_job(struct panfrost_device *pfdev, int slot)
> struct panfrost_job *job = pfdev->jobs[slot][0];
>
> WARN_ON(!job);
> + if (job->is_profiled) {
> + if (job->engine_usage) {
> + job->engine_usage->elapsed_ns[slot] +=
> + ktime_to_ns(ktime_sub(ktime_get(), job->start_time));
> + job->engine_usage->cycles[slot] +=
> + panfrost_cycle_counter_read(pfdev) - job->start_cycles;
> + }
> + panfrost_cycle_counter_put(job->pfdev);
> + }
> +
> pfdev->jobs[slot][0] = pfdev->jobs[slot][1];
> pfdev->jobs[slot][1] = NULL;
>
> @@ -233,6 +243,13 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
> subslot = panfrost_enqueue_job(pfdev, js, job);
> /* Don't queue the job if a reset is in progress */
> if (!atomic_read(&pfdev->reset.pending)) {
> + if (atomic_read(&pfdev->profile_mode)) {
> + panfrost_cycle_counter_get(pfdev);
> + job->is_profiled = true;
> + job->start_time = ktime_get();
> + job->start_cycles = panfrost_cycle_counter_read(pfdev);
> + }
> +
> job_write(pfdev, JS_COMMAND_NEXT(js), JS_COMMAND_START);
> dev_dbg(pfdev->dev,
> "JS: Submitting atom %p to js[%d][%d] with head=0x%llx AS %d",
> @@ -660,10 +677,14 @@ panfrost_reset(struct panfrost_device *pfdev,
> * stuck jobs. Let's make sure the PM counters stay balanced by
> * manually calling pm_runtime_put_noidle() and
> * panfrost_devfreq_record_idle() for each stuck job.
> + * Let's also make sure the cycle counting register's refcnt is
> + * kept balanced to prevent it from running forever
> */
> spin_lock(&pfdev->js->job_lock);
> for (i = 0; i < NUM_JOB_SLOTS; i++) {
> for (j = 0; j < ARRAY_SIZE(pfdev->jobs[0]) && pfdev->jobs[i][j]; j++) {
> + if (pfdev->jobs[i][j]->is_profiled)
> + panfrost_cycle_counter_put(pfdev->jobs[i][j]->pfdev);
> pm_runtime_put_noidle(pfdev->dev);
> panfrost_devfreq_record_idle(&pfdev->pfdevfreq);
> }
> @@ -926,6 +947,9 @@ void panfrost_job_close(struct panfrost_file_priv *panfrost_priv)
> }
>
> job_write(pfdev, JS_COMMAND(i), cmd);
> +
> + /* Jobs can outlive their file context */
> + job->engine_usage = NULL;
> }
> }
> spin_unlock(&pfdev->js->job_lock);
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.h b/drivers/gpu/drm/panfrost/panfrost_job.h
> index 8becc1ba0eb9..17ff808dba07 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.h
> @@ -32,6 +32,11 @@ struct panfrost_job {
>
> /* Fence to be signaled by drm-sched once its done with the job */
> struct dma_fence *render_done_fence;
> +
> + struct panfrost_engine_usage *engine_usage;
> + bool is_profiled;
> + ktime_t start_time;
> + u64 start_cycles;
> };
>
> int panfrost_job_init(struct panfrost_device *pfdev);
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