Hi Christian,

On 31/10/24 17:51, Christian Gmeiner wrote:
From: Christian Gmeiner <cgmei...@igalia.com>

Add a new ioctl, DRM_IOCTL_V3D_PERFMON_SET_GLOBAL, to allow
configuration of a global performance monitor (perfmon).
Use the global perfmon for all jobs to ensure consistent
performance tracking across submissions.

Signed-off-by: Christian Gmeiner <cgmei...@igalia.com>

---
Changes in v2:
- Reworked commit message.
- Removed num_perfmon counter for tracking perfmon allocations.
- Allowing allocation of perfmons when the global perfmon is active.
- Return -EAGAIN for submissions with a per job perfmon if the global perfmon 
is active.
---
  drivers/gpu/drm/v3d/v3d_drv.c     |  1 +
  drivers/gpu/drm/v3d/v3d_drv.h     |  8 ++++++++
  drivers/gpu/drm/v3d/v3d_perfmon.c | 34 +++++++++++++++++++++++++++++++
  drivers/gpu/drm/v3d/v3d_sched.c   | 14 ++++++++++---
  drivers/gpu/drm/v3d/v3d_submit.c  | 10 +++++++++
  include/uapi/drm/v3d_drm.h        | 15 ++++++++++++++
  6 files changed, 79 insertions(+), 3 deletions(-)


[...]

diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c 
b/drivers/gpu/drm/v3d/v3d_perfmon.c
index 156be13ab2ef..bf42303c292b 100644
--- a/drivers/gpu/drm/v3d/v3d_perfmon.c
+++ b/drivers/gpu/drm/v3d/v3d_perfmon.c
@@ -312,6 +312,9 @@ static int v3d_perfmon_idr_del(int id, void *elem, void 
*data)
        if (perfmon == v3d->active_perfmon)
                v3d_perfmon_stop(v3d, perfmon, false);
+ /* If the global perfmon is being destroyed, set it to NULL */
+       cmpxchg(&v3d->global_perfmon, perfmon, NULL);
+
        v3d_perfmon_put(perfmon);
return 0;
@@ -451,3 +454,34 @@ int v3d_perfmon_get_counter_ioctl(struct drm_device *dev, 
void *data,
return 0;
  }
+
+int v3d_perfmon_set_global_ioctl(struct drm_device *dev, void *data,
+                                struct drm_file *file_priv)
+{
+       struct v3d_file_priv *v3d_priv = file_priv->driver_priv;
+       struct drm_v3d_perfmon_set_global *req = data;
+       struct v3d_dev *v3d = to_v3d_dev(dev);
+       struct v3d_perfmon *perfmon;
+
+       if (req->flags & ~DRM_V3D_PERFMON_CLEAR_GLOBAL)
+               return -EINVAL;
+
+       perfmon = v3d_perfmon_find(v3d_priv, req->id);
+       if (!perfmon)
+               return -EINVAL;
+
+       /* If the request is to clear the global performance monitor */
+       if (req->flags & DRM_V3D_PERFMON_CLEAR_GLOBAL) {
+               if (!v3d->global_perfmon)
+                       return -EINVAL;
+
+               xchg(&v3d->global_perfmon, NULL);

I'm reading the userspace code now and I think you need to call
`v3d_perfmon_stop` here to make sure that the active perfmon is no
longer the global perfmon.

Best Regards,
- Maíra

+
+               return 0;
+       }
+
+       if (cmpxchg(&v3d->global_perfmon, NULL, perfmon))
+               return -EBUSY;
+
+       return 0;
+}
diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
index 08d2a2739582..38690740f593 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -120,11 +120,19 @@ v3d_cpu_job_free(struct drm_sched_job *sched_job)
  static void
  v3d_switch_perfmon(struct v3d_dev *v3d, struct v3d_job *job)
  {
-       if (job->perfmon != v3d->active_perfmon)
+       struct v3d_perfmon *perfmon = v3d->global_perfmon;
+
+       if (!perfmon)
+               perfmon = job->perfmon;
+
+       if (perfmon == v3d->active_perfmon)
+               return;
+
+       if (perfmon != v3d->active_perfmon)
                v3d_perfmon_stop(v3d, v3d->active_perfmon, true);
- if (job->perfmon && v3d->active_perfmon != job->perfmon)
-               v3d_perfmon_start(v3d, job->perfmon);
+       if (perfmon && v3d->active_perfmon != perfmon)
+               v3d_perfmon_start(v3d, perfmon);
  }
static void
diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c
index d607aa9c4ec2..9e439c9f0a93 100644
--- a/drivers/gpu/drm/v3d/v3d_submit.c
+++ b/drivers/gpu/drm/v3d/v3d_submit.c
@@ -981,6 +981,11 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
                goto fail;
if (args->perfmon_id) {
+               if (v3d->global_perfmon) {
+                       ret = -EAGAIN;
+                       goto fail_perfmon;
+               }
+
                render->base.perfmon = v3d_perfmon_find(v3d_priv,
                                                        args->perfmon_id);
@@ -1196,6 +1201,11 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
                goto fail;
if (args->perfmon_id) {
+               if (v3d->global_perfmon) {
+                       ret = -EAGAIN;
+                       goto fail_perfmon;
+               }
+
                job->base.perfmon = v3d_perfmon_find(v3d_priv,
                                                     args->perfmon_id);
                if (!job->base.perfmon) {
diff --git a/include/uapi/drm/v3d_drm.h b/include/uapi/drm/v3d_drm.h
index 87fc5bb0a61e..709724fe28e6 100644
--- a/include/uapi/drm/v3d_drm.h
+++ b/include/uapi/drm/v3d_drm.h
@@ -43,6 +43,7 @@ extern "C" {
  #define DRM_V3D_PERFMON_GET_VALUES                0x0a
  #define DRM_V3D_SUBMIT_CPU                        0x0b
  #define DRM_V3D_PERFMON_GET_COUNTER               0x0c
+#define DRM_V3D_PERFMON_SET_GLOBAL                0x0d
#define DRM_IOCTL_V3D_SUBMIT_CL DRM_IOWR(DRM_COMMAND_BASE + DRM_V3D_SUBMIT_CL, struct drm_v3d_submit_cl)
  #define DRM_IOCTL_V3D_WAIT_BO             DRM_IOWR(DRM_COMMAND_BASE + 
DRM_V3D_WAIT_BO, struct drm_v3d_wait_bo)
@@ -61,6 +62,8 @@ extern "C" {
  #define DRM_IOCTL_V3D_SUBMIT_CPU          DRM_IOW(DRM_COMMAND_BASE + 
DRM_V3D_SUBMIT_CPU, struct drm_v3d_submit_cpu)
  #define DRM_IOCTL_V3D_PERFMON_GET_COUNTER DRM_IOWR(DRM_COMMAND_BASE + 
DRM_V3D_PERFMON_GET_COUNTER, \
                                                   struct 
drm_v3d_perfmon_get_counter)
+#define DRM_IOCTL_V3D_PERFMON_SET_GLOBAL  DRM_IOW(DRM_COMMAND_BASE + 
DRM_V3D_PERFMON_SET_GLOBAL, \
+                                                  struct 
drm_v3d_perfmon_set_global)
#define DRM_V3D_SUBMIT_CL_FLUSH_CACHE 0x01
  #define DRM_V3D_SUBMIT_EXTENSION                0x02
@@ -765,6 +768,18 @@ struct drm_v3d_perfmon_get_counter {
        __u8 reserved[7];
  };
+#define DRM_V3D_PERFMON_CLEAR_GLOBAL 0x0001
+
+/*
+ * struct drm_v3d_perfmon_set_global - ioctl to define a
+ * global performance counter that is used if a job has
+ * not assigned one on its own.
+ */
+struct drm_v3d_perfmon_set_global {
+       __u32 flags;
+       __u32 id;
+};
+
  #if defined(__cplusplus)
  }
  #endif

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