[RFC PATCH v3 11/11] drm, cgroup: Allow more aggressive memory reclaim

[Kenny Ho <Kenny.Ho-5C7GfCeVMHo@public.gmane.org>]

Allow DRM TTM memory manager to register a work_struct, such that, when
a drmcgrp is under memory pressure, memory reclaiming can be triggered
immediately.

Change-Id: I25ac04e2db9c19ff12652b88ebff18b44b2706d8
Signed-off-by: Kenny Ho <Kenny.Ho@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c    | 47 +++++++++++++++++++++++++++++++++
 include/drm/drm_cgroup.h        | 14 ++++++++++
 include/drm/ttm/ttm_bo_driver.h |  2 ++
 kernel/cgroup/drm.c             | 33 +++++++++++++++++++++++
 4 files changed, 96 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 79c530f4a198..5fc3bc5bd4c5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1509,6 +1509,44 @@ int ttm_bo_evict_mm(struct ttm_bo_device *bdev, unsigned mem_type)
 }
 EXPORT_SYMBOL(ttm_bo_evict_mm);
 
+static void ttm_bo_reclaim_wq(struct work_struct *work)
+{
+	struct ttm_operation_ctx ctx = {
+		.interruptible = false,
+		.no_wait_gpu = false,
+		.flags = TTM_OPT_FLAG_FORCE_ALLOC
+	};
+	struct ttm_mem_type_manager *man =
+	    container_of(work, struct ttm_mem_type_manager, reclaim_wq);
+	struct ttm_bo_device *bdev = man->bdev;
+	struct dma_fence *fence;
+	int mem_type;
+	int ret;
+
+	for (mem_type = 0; mem_type < TTM_NUM_MEM_TYPES; mem_type++)
+		if (&bdev->man[mem_type] == man)
+			break;
+
+	BUG_ON(mem_type >= TTM_NUM_MEM_TYPES);
+
+	if (!drmcgrp_mem_pressure_scan(bdev, mem_type))
+		return;
+
+	ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx);
+	if (ret)
+		return;
+
+	spin_lock(&man->move_lock);
+	fence = dma_fence_get(man->move);
+	spin_unlock(&man->move_lock);
+
+	if (fence) {
+		ret = dma_fence_wait(fence, false);
+		dma_fence_put(fence);
+	}
+
+}
+
 int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
 			unsigned long p_size)
 {
@@ -1543,6 +1581,13 @@ int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
 		INIT_LIST_HEAD(&man->lru[i]);
 	man->move = NULL;
 
+	pr_err("drmcgrp %p type %d\n", bdev->ddev, type);
+
+	if (type <= TTM_PL_VRAM) {
+		INIT_WORK(&man->reclaim_wq, ttm_bo_reclaim_wq);
+		drmcgrp_register_device_mm(bdev->ddev, type, &man->reclaim_wq);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(ttm_bo_init_mm);
@@ -1620,6 +1665,8 @@ int ttm_bo_device_release(struct ttm_bo_device *bdev)
 		man = &bdev->man[i];
 		if (man->has_type) {
 			man->use_type = false;
+			drmcgrp_unregister_device_mm(bdev->ddev, i);
+			cancel_work_sync(&man->reclaim_wq);
 			if ((i != TTM_PL_SYSTEM) && ttm_bo_clean_mm(bdev, i)) {
 				ret = -EBUSY;
 				pr_err("DRM memory manager type %d is not clean\n",
diff --git a/include/drm/drm_cgroup.h b/include/drm/drm_cgroup.h
index 360c1e6c809f..134d6e5475f3 100644
--- a/include/drm/drm_cgroup.h
+++ b/include/drm/drm_cgroup.h
@@ -5,6 +5,7 @@
 #define __DRM_CGROUP_H__
 
 #include <linux/cgroup_drm.h>
+#include <linux/workqueue.h>
 #include <drm/ttm/ttm_bo_api.h>
 #include <drm/ttm/ttm_bo_driver.h>
 
@@ -12,6 +13,9 @@
 
 int drmcgrp_register_device(struct drm_device *device);
 int drmcgrp_unregister_device(struct drm_device *device);
+void drmcgrp_register_device_mm(struct drm_device *dev, unsigned type,
+		struct work_struct *wq);
+void drmcgrp_unregister_device_mm(struct drm_device *dev, unsigned type);
 bool drmcgrp_is_self_or_ancestor(struct drmcgrp *self,
 		struct drmcgrp *relative);
 void drmcgrp_chg_bo_alloc(struct drmcgrp *drmcgrp, struct drm_device *dev,
@@ -40,6 +44,16 @@ static inline int drmcgrp_unregister_device(struct drm_device *device)
 	return 0;
 }
 
+static inline void drmcgrp_register_device_mm(struct drm_device *dev,
+		unsigned type, struct work_struct *wq)
+{
+}
+
+static inline void drmcgrp_unregister_device_mm(struct drm_device *dev,
+		unsigned type)
+{
+}
+
 static inline bool drmcgrp_is_self_or_ancestor(struct drmcgrp *self,
 		struct drmcgrp *relative)
 {
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 4cbcb41e5aa9..0956ca7888fc 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -205,6 +205,8 @@ struct ttm_mem_type_manager {
 	 * Protected by @move_lock.
 	 */
 	struct dma_fence *move;
+
+	struct work_struct reclaim_wq;
 };
 
 /**
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index 1ce13db36ce9..985a89e849d3 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -31,6 +31,8 @@ struct drmcgrp_device {
 	s64			mem_bw_avg_bytes_per_us_default;
 
 	s64			mem_highs_default[TTM_PL_PRIV+1];
+
+	struct work_struct	*mem_reclaim_wq[TTM_PL_PRIV];
 };
 
 #define DRMCG_CTF_PRIV_SIZE 3
@@ -793,6 +795,31 @@ int drmcgrp_unregister_device(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drmcgrp_unregister_device);
 
+void drmcgrp_register_device_mm(struct drm_device *dev, unsigned type,
+		struct work_struct *wq)
+{
+	if (dev == NULL || dev->primary->index > max_minor
+			|| type >= TTM_PL_PRIV)
+		return;
+
+	mutex_lock(&drmcgrp_mutex);
+	known_drmcgrp_devs[dev->primary->index]->mem_reclaim_wq[type] = wq;
+	mutex_unlock(&drmcgrp_mutex);
+}
+EXPORT_SYMBOL(drmcgrp_register_device_mm);
+
+void drmcgrp_unregister_device_mm(struct drm_device *dev, unsigned type)
+{
+	if (dev == NULL || dev->primary->index > max_minor
+			|| type >= TTM_PL_PRIV)
+		return;
+
+	mutex_lock(&drmcgrp_mutex);
+	known_drmcgrp_devs[dev->primary->index]->mem_reclaim_wq[type] = NULL;
+	mutex_unlock(&drmcgrp_mutex);
+}
+EXPORT_SYMBOL(drmcgrp_unregister_device_mm);
+
 bool drmcgrp_is_self_or_ancestor(struct drmcgrp *self, struct drmcgrp *relative)
 {
 	for (; self != NULL; self = parent_drmcgrp(self))
@@ -1004,6 +1031,12 @@ void drmcgrp_mem_track_move(struct ttm_buffer_object *old_bo, bool evict,
 
 		ddr->mem_bw_stats[DRMCGRP_MEM_BW_ATTR_BYTE_CREDIT]
 			-= move_in_bytes;
+
+		if (known_dev->mem_reclaim_wq[new_mem_type] != NULL &&
+                        ddr->mem_stats[new_mem_type] >
+				ddr->mem_highs[new_mem_type])
+			schedule_work(
+				known_dev->mem_reclaim_wq[new_mem_type]);
 	}
 	mutex_unlock(&known_dev->mutex);
 }
-- 
2.21.0

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