Use an LRU policy to map usermode rings to HW compute queues.

Most compute clients use one queue, and usually the first queue
available. This results in poor pipe/queue work distribution when
multiple compute apps are running. In most cases pipe 0 queue 0 is
the only queue that gets used.

In order to better distribute work across multiple HW queues, we adopt
a policy to map the usermode ring ids to the LRU HW queue.

This fixes a large majority of multi-app compute workloads sharing the
same HW queue, even though 7 other queues are available.

v2: use ring->funcs->type instead of ring->hw_ip
v3: remove amdgpu_queue_mapper_funcs
v4: change ring_lru_list_lock to spinlock, grab only once in lru_get()

Signed-off-by: Andres Rodriguez <andre...@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h           |  3 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c    |  3 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_queue_mgr.c | 38 +++++++++++++++-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c      | 63 +++++++++++++++++++++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h      |  4 ++
 5 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 734d941..88c3176 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1508,20 +1508,23 @@ struct amdgpu_device {
        struct kfd_dev          *kfd;
 
        struct amdgpu_virt      virt;
 
        /* link all shadow bo */
        struct list_head                shadow_list;
        struct mutex                    shadow_list_lock;
        /* link all gtt */
        spinlock_t                      gtt_list_lock;
        struct list_head                gtt_list;
+       /* keep an lru list of rings by HW IP */
+       struct list_head                ring_lru_list;
+       spinlock_t                      ring_lru_list_lock;
 
        /* record hw reset is performed */
        bool has_hw_reset;
 
 };
 
 static inline struct amdgpu_device *amdgpu_ttm_adev(struct ttm_bo_device *bdev)
 {
        return container_of(bdev, struct amdgpu_device, mman.bdev);
 }
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 6abb238..c706805 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1712,20 +1712,23 @@ int amdgpu_device_init(struct amdgpu_device *adev,
        spin_lock_init(&adev->gc_cac_idx_lock);
        spin_lock_init(&adev->audio_endpt_idx_lock);
        spin_lock_init(&adev->mm_stats.lock);
 
        INIT_LIST_HEAD(&adev->shadow_list);
        mutex_init(&adev->shadow_list_lock);
 
        INIT_LIST_HEAD(&adev->gtt_list);
        spin_lock_init(&adev->gtt_list_lock);
 
+       INIT_LIST_HEAD(&adev->ring_lru_list);
+       spin_lock_init(&adev->ring_lru_list_lock);
+
        if (adev->asic_type >= CHIP_BONAIRE) {
                adev->rmmio_base = pci_resource_start(adev->pdev, 5);
                adev->rmmio_size = pci_resource_len(adev->pdev, 5);
        } else {
                adev->rmmio_base = pci_resource_start(adev->pdev, 2);
                adev->rmmio_size = pci_resource_len(adev->pdev, 2);
        }
 
        adev->rmmio = ioremap(adev->rmmio_base, adev->rmmio_size);
        if (adev->rmmio == NULL) {
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_queue_mgr.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_queue_mgr.c
index 3e9ac80..054d750 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_queue_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_queue_mgr.c
@@ -84,20 +84,54 @@ static int amdgpu_identity_map(struct amdgpu_device *adev,
                break;
        default:
                *out_ring = NULL;
                DRM_ERROR("unknown HW IP type: %d\n", mapper->hw_ip);
                return -EINVAL;
        }
 
        return amdgpu_update_cached_map(mapper, ring, *out_ring);
 }
 
+static enum amdgpu_ring_type amdgpu_hw_ip_to_ring_type(int hw_ip)
+{
+       switch (hw_ip) {
+       case AMDGPU_HW_IP_GFX:
+               return AMDGPU_RING_TYPE_GFX;
+       case AMDGPU_HW_IP_COMPUTE:
+               return AMDGPU_RING_TYPE_COMPUTE;
+       case AMDGPU_HW_IP_DMA:
+               return AMDGPU_RING_TYPE_SDMA;
+       case AMDGPU_HW_IP_UVD:
+               return AMDGPU_RING_TYPE_UVD;
+       case AMDGPU_HW_IP_VCE:
+               return AMDGPU_RING_TYPE_VCE;
+       default:
+               DRM_ERROR("Invalid HW IP specified %d\n", hw_ip);
+               return -1;
+       }
+}
+
+static int amdgpu_lru_map(struct amdgpu_device *adev,
+                         struct amdgpu_queue_mapper *mapper,
+                         int user_ring,
+                         struct amdgpu_ring **out_ring)
+{
+       int r;
+       int ring_type = amdgpu_hw_ip_to_ring_type(mapper->hw_ip);
+
+       r = amdgpu_ring_lru_get(adev, ring_type, out_ring);
+       if (r)
+               return r;
+
+       return amdgpu_update_cached_map(mapper, user_ring, *out_ring);
+}
+
 /**
  * amdgpu_queue_mgr_init - init an amdgpu_queue_mgr struct
  *
  * @adev: amdgpu_device pointer
  * @mgr: amdgpu_queue_mgr structure holding queue information
  *
  * Initialize the the selected @mgr (all asics).
  *
  * Returns 0 on success, error on failure.
  */
@@ -205,26 +239,28 @@ int amdgpu_queue_mgr_map(struct amdgpu_device *adev,
 
        *out_ring = amdgpu_get_cached_map(mapper, ring);
        if (*out_ring) {
                /* cache hit */
                r = 0;
                goto out_unlock;
        }
 
        switch (mapper->hw_ip) {
        case AMDGPU_HW_IP_GFX:
-       case AMDGPU_HW_IP_COMPUTE:
        case AMDGPU_HW_IP_DMA:
        case AMDGPU_HW_IP_UVD:
        case AMDGPU_HW_IP_VCE:
                r = amdgpu_identity_map(adev, mapper, ring, out_ring);
                break;
+       case AMDGPU_HW_IP_COMPUTE:
+               r = amdgpu_lru_map(adev, mapper, ring, out_ring);
+               break;
        default:
                *out_ring = NULL;
                r = -EINVAL;
                DRM_ERROR("unknown HW IP type: %d\n", mapper->hw_ip);
        }
 
 out_unlock:
        mutex_unlock(&mapper->lock);
        return r;
 }
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
index 43cd539..d655fa4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
@@ -173,20 +173,22 @@ void amdgpu_ring_commit(struct amdgpu_ring *ring)
        count = ring->funcs->align_mask + 1 -
                (ring->wptr & ring->funcs->align_mask);
        count %= ring->funcs->align_mask + 1;
        ring->funcs->insert_nop(ring, count);
 
        mb();
        amdgpu_ring_set_wptr(ring);
 
        if (ring->funcs->end_use)
                ring->funcs->end_use(ring);
+
+       amdgpu_ring_lru_touch(ring->adev, ring);
 }
 
 /**
  * amdgpu_ring_undo - reset the wptr
  *
  * @ring: amdgpu_ring structure holding ring information
  *
  * Reset the driver's copy of the wptr (all asics).
  */
 void amdgpu_ring_undo(struct amdgpu_ring *ring)
@@ -272,20 +274,22 @@ int amdgpu_ring_init(struct amdgpu_device *adev, struct 
amdgpu_ring *ring,
                                            &ring->gpu_addr,
                                            (void **)&ring->ring);
                if (r) {
                        dev_err(adev->dev, "(%d) ring create failed\n", r);
                        return r;
                }
                memset((void *)ring->ring, 0, ring->ring_size);
        }
        ring->ptr_mask = (ring->ring_size / 4) - 1;
        ring->max_dw = max_dw;
+       INIT_LIST_HEAD(&ring->lru_list);
+       amdgpu_ring_lru_touch(adev, ring);
 
        if (amdgpu_debugfs_ring_init(adev, ring)) {
                DRM_ERROR("Failed to register debugfs file for rings !\n");
        }
        return 0;
 }
 
 /**
  * amdgpu_ring_fini - tear down the driver ring struct.
  *
@@ -305,20 +309,79 @@ void amdgpu_ring_fini(struct amdgpu_ring *ring)
 
        amdgpu_bo_free_kernel(&ring->ring_obj,
                              &ring->gpu_addr,
                              (void **)&ring->ring);
 
        amdgpu_debugfs_ring_fini(ring);
 
        ring->adev->rings[ring->idx] = NULL;
 }
 
+static void amdgpu_ring_lru_touch_locked(struct amdgpu_device *adev,
+                                        struct amdgpu_ring *ring)
+{
+       /* list_move_tail handles the case where ring isn't part of the list */
+       list_move_tail(&ring->lru_list, &adev->ring_lru_list);
+}
+
+/**
+ * amdgpu_ring_lru_get - get the least recently used ring for a HW IP block
+ *
+ * @adev: amdgpu_device pointer
+ * @type: amdgpu_ring_type enum
+ * @ring: output ring
+ *
+ * Retrieve the amdgpu_ring structure for the least recently used ring of
+ * a specific IP block (all asics).
+ * Returns 0 on success, error on failure.
+ */
+int amdgpu_ring_lru_get(struct amdgpu_device *adev, int type,
+                       struct amdgpu_ring **ring)
+{
+       struct amdgpu_ring *entry;
+
+       /* List is sorted in LRU order, find first entry corresponding
+        * to the desired HW IP */
+       *ring = NULL;
+       spin_lock(&adev->ring_lru_list_lock);
+       list_for_each_entry(entry, &adev->ring_lru_list, lru_list) {
+               if (entry->funcs->type == type) {
+                       *ring = entry;
+                       amdgpu_ring_lru_touch_locked(adev, *ring);
+                       break;
+               }
+       }
+       spin_unlock(&adev->ring_lru_list_lock);
+
+       if (!*ring) {
+               DRM_ERROR("Ring LRU contains no entries for ring type:%d\n", 
type);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+/**
+ * amdgpu_ring_lru_touch - mark a ring as recently being used
+ *
+ * @adev: amdgpu_device pointer
+ * @ring: ring to touch
+ *
+ * Move @ring to the tail of the lru list
+ */
+void amdgpu_ring_lru_touch(struct amdgpu_device *adev, struct amdgpu_ring 
*ring)
+{
+       spin_lock(&adev->ring_lru_list_lock);
+       amdgpu_ring_lru_touch_locked(adev, ring);
+       spin_unlock(&adev->ring_lru_list_lock);
+}
+
 /*
  * Debugfs info
  */
 #if defined(CONFIG_DEBUG_FS)
 
 /* Layout of file is 12 bytes consisting of
  * - rptr
  * - wptr
  * - driver's copy of wptr
  *
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index 35da5c5..b51bdcd 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -137,20 +137,21 @@ struct amdgpu_ring_funcs {
        void (*emit_cntxcntl) (struct amdgpu_ring *ring, uint32_t flags);
        void (*emit_rreg)(struct amdgpu_ring *ring, uint32_t reg);
        void (*emit_wreg)(struct amdgpu_ring *ring, uint32_t reg, uint32_t val);
 };
 
 struct amdgpu_ring {
        struct amdgpu_device            *adev;
        const struct amdgpu_ring_funcs  *funcs;
        struct amdgpu_fence_driver      fence_drv;
        struct amd_gpu_scheduler        sched;
+       struct list_head                lru_list;
 
        struct amdgpu_bo        *ring_obj;
        volatile uint32_t       *ring;
        unsigned                rptr_offs;
        unsigned                wptr;
        unsigned                wptr_old;
        unsigned                ring_size;
        unsigned                max_dw;
        int                     count_dw;
        uint64_t                gpu_addr;
@@ -179,12 +180,15 @@ int amdgpu_ring_is_valid_index(struct amdgpu_device *adev,
                               int hw_ip, int ring);
 int amdgpu_ring_alloc(struct amdgpu_ring *ring, unsigned ndw);
 void amdgpu_ring_insert_nop(struct amdgpu_ring *ring, uint32_t count);
 void amdgpu_ring_generic_pad_ib(struct amdgpu_ring *ring, struct amdgpu_ib 
*ib);
 void amdgpu_ring_commit(struct amdgpu_ring *ring);
 void amdgpu_ring_undo(struct amdgpu_ring *ring);
 int amdgpu_ring_init(struct amdgpu_device *adev, struct amdgpu_ring *ring,
                     unsigned ring_size, struct amdgpu_irq_src *irq_src,
                     unsigned irq_type);
 void amdgpu_ring_fini(struct amdgpu_ring *ring);
+int amdgpu_ring_lru_get(struct amdgpu_device *adev, int hw_ip,
+                       struct amdgpu_ring **ring);
+void amdgpu_ring_lru_touch(struct amdgpu_device *adev, struct amdgpu_ring 
*ring);
 
 #endif
-- 
2.9.3

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