[PATCH 1/1] drm/amdkfd: Add eviction debug messages

[Felix Kuehling]

Use WARN to print messages with backtrace when evictions are triggered.
This can help determine the root cause of evictions and help spot driver
bugs triggering evictions unintentionally, or help with performance tuning
by avoiding conditions that cause evictions in a specific workload.

The messages are controlled by a new module parameter that can be changed
at runtime:

  echo Y > /sys/module/amdgpu/parameters/debug_evictions
  echo N > /sys/module/amdgpu/parameters/debug_evictions

Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h      | 2 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c  | 8 ++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 2 ++
 drivers/gpu/drm/amd/amdkfd/kfd_device.c  | 3 +++
 drivers/gpu/drm/amd/amdkfd/kfd_priv.h    | 5 +++++
 5 files changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 10ae92e835f6..6c7dd0a707c9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -186,8 +186,10 @@ extern int amdgpu_noretry;
 extern int amdgpu_force_asic_type;
 #ifdef CONFIG_HSA_AMD
 extern int sched_policy;
+extern bool debug_evictions;
 #else
 static const int sched_policy = KFD_SCHED_POLICY_HWS;
+static const bool debug_evictions; /* = false */
 #endif
 
 extern int amdgpu_tmz;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index d4d7cca1cc72..fdf350d5e7b7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -705,6 +705,14 @@ MODULE_PARM_DESC(hws_gws_support, "Assume MEC2 FW supports GWS barriers (false =
 int queue_preemption_timeout_ms = 9000;
 module_param(queue_preemption_timeout_ms, int, 0644);
 MODULE_PARM_DESC(queue_preemption_timeout_ms, "queue preemption timeout in ms (1 = Minimum, 9000 = default)");
+
+/**
+ * DOC: debug_evictions(bool)
+ * Enable extra debug messages to help determine the cause of evictions
+ */
+bool debug_evictions;
+module_param(debug_evictions, bool, 0644);
+MODULE_PARM_DESC(debug_evictions, "enable eviction debug messages (false = default)");
 #endif
 
 /**
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
index b87ca171986a..072f0e1185a8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
@@ -275,6 +275,8 @@ int amdgpu_sync_resv(struct amdgpu_device *adev, struct amdgpu_sync *sync,
 			continue;
 		}
 
+		WARN(debug_evictions && fence_owner == AMDGPU_FENCE_OWNER_KFD,
+		     "Adding eviction fence to sync obj");
 		r = amdgpu_sync_fence(sync, f, false);
 		if (r)
 			break;
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index 22348cebaf36..80393e0583bb 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
@@ -942,6 +942,7 @@ int kgd2kfd_quiesce_mm(struct mm_struct *mm)
 	if (!p)
 		return -ESRCH;
 
+	WARN(debug_evictions, "Evicting pid %d", p->lead_thread->pid);
 	r = kfd_process_evict_queues(p);
 
 	kfd_unref_process(p);
@@ -1009,6 +1010,8 @@ int kgd2kfd_schedule_evict_and_restore_process(struct mm_struct *mm,
 	/* During process initialization eviction_work.dwork is initialized
 	 * to kfd_evict_bo_worker
 	 */
+	WARN(debug_evictions, "Scheduling eviction of pid %d in %ld jiffies",
+	     p->lead_thread->pid, delay_jiffies);
 	schedule_delayed_work(&p->eviction_work, delay_jiffies);
 out:
 	kfd_unref_process(p);
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index 173d58b2d81f..51ba2020732e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -177,6 +177,11 @@ extern bool hws_gws_support;
  */
 extern int queue_preemption_timeout_ms;
 
+/*
+ * Enable eviction debug messages
+ */
+extern bool debug_evictions;
+
 enum cache_policy {
 	cache_policy_coherent,
 	cache_policy_noncoherent
-- 
2.17.1