[PATCH 4/4] drm/amd/amdkfd: Surface files in Sysfs to allow users to get number of compute units that are in use.

[Ramesh Errabolu]

[Why]
Allow user to know how many compute units (CU) are in use at any given
moment.

[How]
Surface files in Sysfs that allow user to determine the number of compute
units that are in use for a given process. One Sysfs file is used per
device.

Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_priv.h    | 25 +++++++++
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 71 +++++++++++++++++++++++-
 2 files changed, 94 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index 56f92cfff591..b7be5c5751b7 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -705,6 +705,31 @@ struct kfd_process_device {
 
 	struct kobject *kobj_stats;
 	unsigned int doorbell_index;
+
+	/*
+	 * @cu_occupancy: Reports occupancy of Compute Units (CU) of a process
+	 * that is associated with device encoded by "this" struct instance. The
+	 * value reflects CU usage by all of the waves launched by this process
+	 * on this device. A very important property of occupancy parameter is
+	 * that its value is a snapshot of current use.
+	 *
+	 * Following is to be noted regarding how this parameter is reported:
+	 *
+	 *  The number of waves that a CU can launch is limited by couple of
+	 *  parameters. These are encoded by struct amdgpu_cu_info instance
+	 *  that is part of every device definition. For GFX9 devices this
+	 *  translates to 40 waves (simd_per_cu * max_waves_per_simd) when waves
+	 *  do not use scratch memory and 32 waves (max_scratch_slots_per_cu)
+	 *  when they do use scratch memory. This could change for future
+	 *  devices and therefore this example should be considered as a guide.
+	 *
+	 *  All CU's of a device are available for the process. This may not be true
+	 *  under certain conditions - e.g. CU masking.
+	 *
+	 *  Finally number of CU's that are occupied by a process is affected by both
+	 *  number of CU's a device has along with number of other competing processes
+	 */
+	struct attribute attr_cu_occupancy;
 };
 
 #define qpd_to_pdd(x) container_of(x, struct kfd_process_device, qpd)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 17d909c86f50..2807e1c4d59b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -249,6 +249,52 @@ static void kfd_sdma_activity_worker(struct work_struct *work)
 	}
 }
 
+/**
+ * @kfd_get_cu_occupancy() - Collect number of waves in-flight on this device
+ * by current process. Translates acquired wave count into number of compute units
+ * that are occupied.
+ *
+ * @atr: Handle of attribute that allows reporting of wave count. The attribute
+ * handle encapsulates GPU device it is associated with, thereby allowing collection
+ * of waves in flight, etc
+ *
+ * @buffer: Handle of user provided buffer updated with wave count
+ *
+ * Return: Number of bytes written to user buffer or an error value
+ */
+static int kfd_get_cu_occupancy(struct attribute *attr, char *buffer)
+{
+	int cu_cnt;
+	int wave_cnt;
+	int max_waves_per_cu;
+	struct kfd_dev *dev = NULL;
+	struct kfd_process *proc = NULL;
+	struct kfd_process_device *pdd = NULL;
+
+	pdd = container_of(attr, struct kfd_process_device, attr_cu_occupancy);
+	dev = pdd->dev;
+	if (dev->kfd2kgd->get_cu_occupancy == NULL)
+		return -EINVAL;
+
+	cu_cnt = 0;
+	proc = pdd->process;
+	if (pdd->qpd.queue_count == 0) {
+		pr_debug("Gpu-Id: %d has no active queues for process %d\n",
+			 dev->id, proc->pasid);
+		return snprintf(buffer, PAGE_SIZE, "%d\n", cu_cnt);
+	}
+
+	/* Collect wave count from device if it supports */
+	wave_cnt = 0;
+	max_waves_per_cu = 0;
+	dev->kfd2kgd->get_cu_occupancy(dev->kgd, proc->pasid, &wave_cnt,
+			&max_waves_per_cu);
+
+	/* Translate wave count to number of compute units */
+	cu_cnt = (wave_cnt + (max_waves_per_cu - 1)) / max_waves_per_cu;
+	return snprintf(buffer, PAGE_SIZE, "%d\n", cu_cnt);
+}
+
 static ssize_t kfd_procfs_show(struct kobject *kobj, struct attribute *attr,
 			       char *buffer)
 {
@@ -344,6 +390,7 @@ static ssize_t kfd_procfs_queue_show(struct kobject *kobj,
 
 	return 0;
 }
+
 static ssize_t kfd_procfs_stats_show(struct kobject *kobj,
 				     struct attribute *attr, char *buffer)
 {
@@ -359,8 +406,13 @@ static ssize_t kfd_procfs_stats_show(struct kobject *kobj,
 				PAGE_SIZE,
 				"%llu\n",
 				jiffies64_to_msecs(evict_jiffies));
-	} else
+
+	/* Sysfs handle that gets CU occupancy is per device */
+	} else if (strcmp(attr->name, "cu_occupancy") == 0) {
+		return kfd_get_cu_occupancy(attr, buffer);
+	} else {
 		pr_err("Invalid attribute");
+	}
 
 	return 0;
 }
@@ -466,6 +518,7 @@ static int kfd_procfs_add_sysfs_stats(struct kfd_process *p)
 	 * Create sysfs files for each GPU:
 	 * - proc/<pid>/stats_<gpuid>/
 	 * - proc/<pid>/stats_<gpuid>/evicted_ms
+	 * - proc/<pid>/stats_<gpuid>/cu_occupancy
 	 */
 	list_for_each_entry(pdd, &p->per_device_data, per_device_list) {
 		struct kobject *kobj_stats;
@@ -496,6 +549,19 @@ static int kfd_procfs_add_sysfs_stats(struct kfd_process *p)
 		if (ret)
 			pr_warn("Creating eviction stats for gpuid %d failed",
 					(int)pdd->dev->id);
+
+		/* Add sysfs file to report compute unit occupancy */
+		if (pdd->dev->kfd2kgd->get_cu_occupancy != NULL) {
+			pdd->attr_cu_occupancy.name = "cu_occupancy";
+			pdd->attr_cu_occupancy.mode = KFD_SYSFS_FILE_MODE;
+			sysfs_attr_init(&pdd->attr_cu_occupancy);
+			ret = sysfs_create_file(kobj_stats,
+						&pdd->attr_cu_occupancy);
+			if (ret)
+				pr_warn("Creating %s failed for gpuid: %d",
+					pdd->attr_cu_occupancy.name,
+					(int)pdd->dev->id);
+		}
 	}
 err:
 	return ret;
@@ -537,7 +603,6 @@ static int kfd_procfs_add_sysfs_files(struct kfd_process *p)
 	return ret;
 }
 
-
 void kfd_procfs_del_queue(struct queue *q)
 {
 	if (!q)
@@ -909,6 +974,8 @@ static void kfd_process_wq_release(struct work_struct *work)
 			sysfs_remove_file(p->kobj, &pdd->attr_vram);
 			sysfs_remove_file(p->kobj, &pdd->attr_sdma);
 			sysfs_remove_file(p->kobj, &pdd->attr_evict);
+			if (pdd->dev->kfd2kgd->get_cu_occupancy != NULL)
+				sysfs_remove_file(p->kobj, &pdd->attr_cu_occupancy);
 			kobject_del(pdd->kobj_stats);
 			kobject_put(pdd->kobj_stats);
 			pdd->kobj_stats = NULL;
-- 
2.27.0