Re: [PATCH 2/2] drm/v3d: Expose the total GPU usage stats on debugfs

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On 28/07/2023 12:25, Maira Canal wrote:

Hi,

On 7/28/23 07:16, Tvrtko Ursulin wrote:


Hi,

On 27/07/2023 15:23, Maíra Canal wrote:

The previous patch exposed the accumulated amount of active time per
client for each V3D queue. But this doesn't provide a global notion of
the GPU usage.

Therefore, provide the accumulated amount of active time for each V3D
queue (BIN, RENDER, CSD, TFU and CACHE_CLEAN), considering all the jobs
submitted to the queue, independent of the client.

This data is exposed through the debugfs interface, so that if the
interface is queried at two different points of time the usage percentage 
of each of the queues can be calculated.
Just passing observation - I've noticed a mismatch between fdinfo and debugfs in terms of ABI stability and production availability.
Not sure if it matters for your intended use cases, just saying that if you plan to have an user facing tool similar to what we have in intel_gpu_top, debugfs may not be the best choice. 

Do you have a suggestion of a better interface that could be used to
expose this data?

It would be nice to have something generic, similar to fdinfo, to expose
global GPU stats. This way we could expose global GPU stats on gputop,
which would be great.


I think there is at least two options.
With i915 we use perf/PMU, drawback (or not, depends on the view point) is that it requires CAP_SYS_PERFMON. Fits well for exposing global GPU hardware counters.
You could go the sysfs route, which would be ABI stable and available in production. This could either be attempted to be somewhat DRM standardized (ala fdinfo), or driver specific. 

Maybe someone has more ideas.

Regards,

Tvrtko



Best Regards,
- Maíra



Regards,

Tvrtko


Co-developed-by: Jose Maria Casanova Crespo <jmcasanova@xxxxxxxxxx>
Signed-off-by: Jose Maria Casanova Crespo <jmcasanova@xxxxxxxxxx>
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
  drivers/gpu/drm/v3d/v3d_debugfs.c | 27 +++++++++++++++++++++++++++
  drivers/gpu/drm/v3d/v3d_drv.h     |  3 +++
  drivers/gpu/drm/v3d/v3d_gem.c     |  5 ++++-
  drivers/gpu/drm/v3d/v3d_irq.c     | 24 ++++++++++++++++++++----
  drivers/gpu/drm/v3d/v3d_sched.c   | 13 ++++++++++++-
  5 files changed, 66 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/v3d/v3d_debugfs.c b/drivers/gpu/drm/v3d/v3d_debugfs.c 
index 330669f51fa7..3b7329343649 100644
--- a/drivers/gpu/drm/v3d/v3d_debugfs.c
+++ b/drivers/gpu/drm/v3d/v3d_debugfs.c
@@ -4,6 +4,7 @@
  #include <linux/circ_buf.h>
  #include <linux/ctype.h>
  #include <linux/debugfs.h>
+#include <linux/sched/clock.h>
  #include <linux/seq_file.h>
  #include <linux/string_helpers.h>
@@ -236,11 +237,37 @@ static int v3d_measure_clock(struct seq_file *m, void *unused) 
      return 0;
  }

+static int v3d_debugfs_gpu_usage(struct seq_file *m, void *unused)
+{
+    struct drm_debugfs_entry *entry = m->private;
+    struct drm_device *dev = entry->dev;
+    struct v3d_dev *v3d = to_v3d_dev(dev);
+    enum v3d_queue queue;
+    u64 timestamp = local_clock();
+    u64 active_runtime;
+
+    seq_printf(m, "timestamp: %llu\n", timestamp);
+
+    for (queue = 0; queue < V3D_MAX_QUEUES; queue++) {
+        if (v3d->queue[queue].start_ns)
+            active_runtime = timestamp - v3d->queue[queue].start_ns;
+        else
+            active_runtime = 0;
+
+        seq_printf(m, "%s: %llu ns\n",
+               v3d_queue_to_string(queue),
+               v3d->queue[queue].enabled_ns + active_runtime);
+    }
+
+    return 0;
+}
+
  static const struct drm_debugfs_info v3d_debugfs_list[] = {
      {"v3d_ident", v3d_v3d_debugfs_ident, 0},
      {"v3d_regs", v3d_v3d_debugfs_regs, 0},
      {"measure_clock", v3d_measure_clock, 0},
      {"bo_stats", v3d_debugfs_bo_stats, 0},
+    {"gpu_usage", v3d_debugfs_gpu_usage, 0},
  };

  void
diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h 
index ee5e12d0db1c..b41b32ecd991 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -38,6 +38,9 @@ struct v3d_queue_state {

      u64 fence_context;
      u64 emit_seqno;
+
+    u64 start_ns;
+    u64 enabled_ns;
  };
  /* Performance monitor object. The perform lifetime is controlled by userspace diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c 
index 40ed0c7c3fad..630ea2db8f8f 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -1014,8 +1014,11 @@ v3d_gem_init(struct drm_device *dev)
      u32 pt_size = 4096 * 1024;
      int ret, i;

-    for (i = 0; i < V3D_MAX_QUEUES; i++)
+    for (i = 0; i < V3D_MAX_QUEUES; i++) {
          v3d->queue[i].fence_context = dma_fence_context_alloc(1);
+        v3d->queue[i].start_ns = 0;
+        v3d->queue[i].enabled_ns = 0;
+    }

      spin_lock_init(&v3d->mm_lock);
      spin_lock_init(&v3d->job_lock);
diff --git a/drivers/gpu/drm/v3d/v3d_irq.c b/drivers/gpu/drm/v3d/v3d_irq.c 
index c898800ae9c2..be4ff7559309 100644
--- a/drivers/gpu/drm/v3d/v3d_irq.c
+++ b/drivers/gpu/drm/v3d/v3d_irq.c
@@ -102,9 +102,13 @@ v3d_irq(int irq, void *arg)
          struct v3d_fence *fence =
              to_v3d_fence(v3d->bin_job->base.irq_fence);
          struct v3d_file_priv *file = v3d->bin_job->base.file->driver_priv; 
+        u64 runtime = local_clock() - file->start_ns[V3D_BIN];
-        file->enabled_ns[V3D_BIN] += local_clock() - file->start_ns[V3D_BIN]; 
          file->start_ns[V3D_BIN] = 0;
+        v3d->queue[V3D_BIN].start_ns = 0;
+
+        file->enabled_ns[V3D_BIN] += runtime;
+        v3d->queue[V3D_BIN].enabled_ns += runtime;

          trace_v3d_bcl_irq(&v3d->drm, fence->seqno);
          dma_fence_signal(&fence->base);
@@ -115,9 +119,13 @@ v3d_irq(int irq, void *arg)
          struct v3d_fence *fence =
              to_v3d_fence(v3d->render_job->base.irq_fence);
          struct v3d_file_priv *file = v3d->render_job->base.file->driver_priv; 
+        u64 runtime = local_clock() - file->start_ns[V3D_RENDER];
-        file->enabled_ns[V3D_RENDER] += local_clock() - file->start_ns[V3D_RENDER]; 
          file->start_ns[V3D_RENDER] = 0;
+        v3d->queue[V3D_RENDER].start_ns = 0;
+
+        file->enabled_ns[V3D_RENDER] += runtime;
+        v3d->queue[V3D_RENDER].enabled_ns += runtime;

          trace_v3d_rcl_irq(&v3d->drm, fence->seqno);
          dma_fence_signal(&fence->base);
@@ -128,9 +136,13 @@ v3d_irq(int irq, void *arg)
          struct v3d_fence *fence =
              to_v3d_fence(v3d->csd_job->base.irq_fence);
          struct v3d_file_priv *file = v3d->csd_job->base.file->driver_priv; 
+        u64 runtime = local_clock() - file->start_ns[V3D_CSD];
-        file->enabled_ns[V3D_CSD] += local_clock() - file->start_ns[V3D_CSD]; 
          file->start_ns[V3D_CSD] = 0;
+        v3d->queue[V3D_CSD].start_ns = 0;
+
+        file->enabled_ns[V3D_CSD] += runtime;
+        v3d->queue[V3D_CSD].enabled_ns += runtime;

          trace_v3d_csd_irq(&v3d->drm, fence->seqno);
          dma_fence_signal(&fence->base);
@@ -168,9 +180,13 @@ v3d_hub_irq(int irq, void *arg)
          struct v3d_fence *fence =
              to_v3d_fence(v3d->tfu_job->base.irq_fence);
          struct v3d_file_priv *file = v3d->tfu_job->base.file->driver_priv; 
+        u64 runtime = local_clock() - file->start_ns[V3D_TFU];
-        file->enabled_ns[V3D_TFU] += local_clock() - file->start_ns[V3D_TFU]; 
          file->start_ns[V3D_TFU] = 0;
+        v3d->queue[V3D_TFU].start_ns = 0;
+
+        file->enabled_ns[V3D_TFU] += runtime;
+        v3d->queue[V3D_TFU].enabled_ns += runtime;

          trace_v3d_tfu_irq(&v3d->drm, fence->seqno);
          dma_fence_signal(&fence->base);
diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c 
index b360709c0765..1a9c7f395862 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -110,6 +110,7 @@ static struct dma_fence *v3d_bin_job_run(struct drm_sched_job *sched_job) 
                  job->start, job->end);

      file->start_ns[V3D_BIN] = local_clock();
+    v3d->queue[V3D_BIN].start_ns = file->start_ns[V3D_BIN];
      file->jobs_sent[V3D_BIN]++;

      v3d_switch_perfmon(v3d, &job->base);
@@ -165,6 +166,7 @@ static struct dma_fence *v3d_render_job_run(struct drm_sched_job *sched_job) 
                  job->start, job->end);

      file->start_ns[V3D_RENDER] = local_clock();
+    v3d->queue[V3D_RENDER].start_ns = file->start_ns[V3D_RENDER];
      file->jobs_sent[V3D_RENDER]++;

      v3d_switch_perfmon(v3d, &job->base);
@@ -201,6 +203,7 @@ v3d_tfu_job_run(struct drm_sched_job *sched_job)
      trace_v3d_submit_tfu(dev, to_v3d_fence(fence)->seqno);

      file->start_ns[V3D_TFU] = local_clock();
+    v3d->queue[V3D_TFU].start_ns = file->start_ns[V3D_TFU];
      file->jobs_sent[V3D_TFU]++;

      V3D_WRITE(V3D_TFU_IIA, job->args.iia);
@@ -246,6 +249,7 @@ v3d_csd_job_run(struct drm_sched_job *sched_job)
      trace_v3d_submit_csd(dev, to_v3d_fence(fence)->seqno);

      file->start_ns[V3D_CSD] = local_clock();
+    v3d->queue[V3D_CSD].start_ns = file->start_ns[V3D_CSD];
      file->jobs_sent[V3D_CSD]++;

      v3d_switch_perfmon(v3d, &job->base);
@@ -264,14 +268,21 @@ v3d_cache_clean_job_run(struct drm_sched_job *sched_job) 
      struct v3d_job *job = to_v3d_job(sched_job);
      struct v3d_dev *v3d = job->v3d;
      struct v3d_file_priv *file = job->file->driver_priv;
+    u64 runtime;

      file->start_ns[V3D_CACHE_CLEAN] = local_clock();
+    v3d->queue[V3D_CACHE_CLEAN].start_ns = file->start_ns[V3D_CACHE_CLEAN]; 
      file->jobs_sent[V3D_CACHE_CLEAN]++;

      v3d_clean_caches(v3d);
-    file->enabled_ns[V3D_CACHE_CLEAN] += local_clock() - file->start_ns[V3D_CACHE_CLEAN]; 
+    runtime = local_clock() - file->start_ns[V3D_CACHE_CLEAN];
+
+    file->enabled_ns[V3D_CACHE_CLEAN] += runtime;
+    v3d->queue[V3D_CACHE_CLEAN].enabled_ns += runtime;
+
      file->start_ns[V3D_CACHE_CLEAN] = 0;
+    v3d->queue[V3D_CACHE_CLEAN].start_ns = 0;

      return NULL;
  }
--
2.41.0
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