[PATCH v3 4/8] drm/panfrost: Add fdinfo support GPU load metrics

Adrián Larumbe
2023-09-05T19:11:50Z

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.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
drivers/gpu/drm/panfrost/panfrost_devfreq.c | 8 +++
drivers/gpu/drm/panfrost/panfrost_devfreq.h | 3 ++
drivers/gpu/drm/panfrost/panfrost_device.h | 13 +++++
drivers/gpu/drm/panfrost/panfrost_drv.c | 59 ++++++++++++++++++++-
drivers/gpu/drm/panfrost/panfrost_job.c | 27 ++++++++++
drivers/gpu/drm/panfrost/panfrost_job.h | 4 ++
6 files changed, 113 insertions(+), 1 deletion(-)

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.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index 5c09c9f3ae08..7ad3973b1a3a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -24,6 +24,7 @@ struct panfrost_perfcnt;

#define NUM_JOB_SLOTS 3
#define MAX_PM_DOMAINS 5
+#define MAX_SLOT_NAME_LEN 25

struct panfrost_features {
u16 id;
@@ -141,12 +142,24 @@ struct panfrost_mmu {
struct list_head list;
};

+struct drm_info_gpu {
+ unsigned long maxfreq;
+
+ struct engine_info {
+ unsigned long long elapsed_ns;
+ unsigned long long cycles;
+ char name[MAX_SLOT_NAME_LEN];
+ } engines[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 drm_info_gpu fdinfo;
};

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 2dfd9f79a31b..94787f4aee27 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -268,6 +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->priv = file_priv;

slot = panfrost_job_get_slot(job);

@@ -484,6 +485,14 @@ panfrost_open(struct drm_device *dev, struct drm_file *file)
goto err_free;
}

+ snprintf(panfrost_priv->fdinfo.engines[0].name, MAX_SLOT_NAME_LEN, "fragment");
+ snprintf(panfrost_priv->fdinfo.engines[1].name, MAX_SLOT_NAME_LEN, "vertex-tiler");
+/* Not exposed to userspace yet */
+#if 0
+ snprintf(panfrost_priv->fdinfo.engines[2].name, MAX_SLOT_NAME_LEN, "compute-only");
+#endif
+ panfrost_priv->fdinfo.maxfreq = pfdev->pfdevfreq.fast_rate;
+
ret = panfrost_job_open(panfrost_priv);
if (ret)
goto err_job;
@@ -524,7 +533,54 @@ 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.
+ */
+
+ for (i = 0; i < NUM_JOB_SLOTS - 1; i++) {
+ struct engine_info *ei = &panfrost_priv->fdinfo.engines[i];
+
+ drm_printf(p, "drm-engine-%s:\t%llu ns\n",
+ ei->name, ei->elapsed_ns);
+ drm_printf(p, "drm-cycles-%s:\t%llu\n",
+ ei->name, ei->cycles);
+ drm_printf(p, "drm-maxfreq-%s:\t%lu Hz\n",
+ ei->name, panfrost_priv->fdinfo.maxfreq);
+ drm_printf(p, "drm-curfreq-%s:\t%lu Hz\n",
+ ei->name, pfdev->pfdevfreq.current_frequency);
+ }
+}
+
+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:
@@ -536,6 +592,7 @@ 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,
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 8b1bf6ac48f8..8a02e1ee9f9b 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -159,6 +159,25 @@ panfrost_dequeue_job(struct panfrost_device *pfdev, int slot)
struct panfrost_job *job = pfdev->jobs[slot][0];

WARN_ON(!job);
+ if (job->priv) {
+ struct engine_info *engine_info = &job->priv->fdinfo.engines[slot];
+
+ if (atomic_read(&pfdev->profile_mode)) {
+ engine_info->elapsed_ns +=
+ ktime_to_ns(ktime_sub(ktime_get(), job->start_time));
+ engine_info->cycles +=
+ panfrost_cycle_counter_read(pfdev) - job->start_cycles;
+
+ /* Reset in case the job has to be requeued */
+ job->start_time = 0;
+ /* A GPU reset puts the Cycle Counter register back to 0 */
+ job->start_cycles = atomic_read(&pfdev->reset.pending) ?
+ 0 : panfrost_cycle_counter_read(pfdev);
+ }
+ } else
+ dev_WARN(pfdev->dev, "Panfrost DRM file closed when job was on flight\n");
+
+
pfdev->jobs[slot][0] = pfdev->jobs[slot][1];
pfdev->jobs[slot][1] = NULL;

@@ -233,6 +252,11 @@ 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)) {
+ 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",
@@ -936,6 +960,9 @@ void panfrost_job_close(struct panfrost_file_priv *panfrost_priv)
}

job_write(pfdev, JS_COMMAND(i), cmd);
+
+ /* Jobs can outlive their file context */
+ job->priv = 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 2aa0add35459..63bc830e057d 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.h
+++ b/drivers/gpu/drm/panfrost/panfrost_job.h
@@ -32,7 +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_file_priv *priv;
bool is_profiled;
+ ktime_t start_time;
+ u64 start_cycles;
};

int panfrost_job_init(struct panfrost_device *pfdev);
--
2.42.0