drm/i915/bdw: Pin the context backing objects to GGTT on-demand
Up until now, we have pinned every logical ring context backing object
during creation, and left it pinned until destruction. This made my life
easier, but it's a harmful thing to do, because we cause fragmentation
of the GGTT (and, eventually, we would run out of space).
This patch makes the pinning on-demand: the backing objects of the two
contexts that are written to the ELSP are pinned right before submission
and unpinned once the hardware is done with them. The only context that
is still pinned regardless is the global default one, so that the HWS can
still be accessed in the same way (ring->status_page).
v2: In the early version of this patch, we were pinning the context as
we put it into the ELSP: on the one hand, this is very efficient because
only a maximum two contexts are pinned at any given time, but on the other
hand, we cannot really pin in interrupt time :(
v3: Use a mutex rather than atomic_t to protect pin count to avoid races.
Do not unpin default context in free_request.
v4: Break out pin and unpin into functions. Fix style problems reported
by checkpatch
v5: Remove unpin_lock as all pinning and unpinning is done with the struct
mutex already locked. Add WARN_ONs to make sure this is the case in future.
Issue: VIZ-4277
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
Reviewed-by: Akash Goel <akash.goels@gmail.com>
Reviewed-by: Deepak S<deepak.s@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index c855051..9560e63 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -140,8 +140,6 @@
#define GEN8_LR_CONTEXT_RENDER_SIZE (20 * PAGE_SIZE)
#define GEN8_LR_CONTEXT_OTHER_SIZE (2 * PAGE_SIZE)
-#define GEN8_LR_CONTEXT_ALIGN 4096
-
#define RING_EXECLIST_QFULL (1 << 0x2)
#define RING_EXECLIST1_VALID (1 << 0x3)
#define RING_EXECLIST0_VALID (1 << 0x4)
@@ -814,9 +812,40 @@
execlists_context_queue(ring, ctx, ringbuf->tail);
}
+static int intel_lr_context_pin(struct intel_engine_cs *ring,
+ struct intel_context *ctx)
+{
+ struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
+ int ret = 0;
+
+ WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
+ if (ctx->engine[ring->id].unpin_count++ == 0) {
+ ret = i915_gem_obj_ggtt_pin(ctx_obj,
+ GEN8_LR_CONTEXT_ALIGN, 0);
+ if (ret)
+ ctx->engine[ring->id].unpin_count = 0;
+ }
+
+ return ret;
+}
+
+void intel_lr_context_unpin(struct intel_engine_cs *ring,
+ struct intel_context *ctx)
+{
+ struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
+
+ if (ctx_obj) {
+ WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
+ if (--ctx->engine[ring->id].unpin_count == 0)
+ i915_gem_object_ggtt_unpin(ctx_obj);
+ }
+}
+
static int logical_ring_alloc_seqno(struct intel_engine_cs *ring,
struct intel_context *ctx)
{
+ int ret;
+
if (ring->outstanding_lazy_seqno)
return 0;
@@ -827,6 +856,14 @@
if (request == NULL)
return -ENOMEM;
+ if (ctx != ring->default_context) {
+ ret = intel_lr_context_pin(ring, ctx);
+ if (ret) {
+ kfree(request);
+ return ret;
+ }
+ }
+
/* Hold a reference to the context this request belongs to
* (we will need it when the time comes to emit/retire the
* request).
@@ -1680,12 +1717,16 @@
for (i = 0; i < I915_NUM_RINGS; i++) {
struct drm_i915_gem_object *ctx_obj = ctx->engine[i].state;
- struct intel_ringbuffer *ringbuf = ctx->engine[i].ringbuf;
if (ctx_obj) {
+ struct intel_ringbuffer *ringbuf =
+ ctx->engine[i].ringbuf;
+ struct intel_engine_cs *ring = ringbuf->ring;
+
intel_destroy_ringbuffer_obj(ringbuf);
kfree(ringbuf);
- i915_gem_object_ggtt_unpin(ctx_obj);
+ if (ctx == ring->default_context)
+ i915_gem_object_ggtt_unpin(ctx_obj);
drm_gem_object_unreference(&ctx_obj->base);
}
}
@@ -1748,6 +1789,7 @@
int intel_lr_context_deferred_create(struct intel_context *ctx,
struct intel_engine_cs *ring)
{
+ const bool is_global_default_ctx = (ctx == ring->default_context);
struct drm_device *dev = ring->dev;
struct drm_i915_gem_object *ctx_obj;
uint32_t context_size;
@@ -1767,18 +1809,22 @@
return ret;
}
- ret = i915_gem_obj_ggtt_pin(ctx_obj, GEN8_LR_CONTEXT_ALIGN, 0);
- if (ret) {
- DRM_DEBUG_DRIVER("Pin LRC backing obj failed: %d\n", ret);
- drm_gem_object_unreference(&ctx_obj->base);
- return ret;
+ if (is_global_default_ctx) {
+ ret = i915_gem_obj_ggtt_pin(ctx_obj, GEN8_LR_CONTEXT_ALIGN, 0);
+ if (ret) {
+ DRM_DEBUG_DRIVER("Pin LRC backing obj failed: %d\n",
+ ret);
+ drm_gem_object_unreference(&ctx_obj->base);
+ return ret;
+ }
}
ringbuf = kzalloc(sizeof(*ringbuf), GFP_KERNEL);
if (!ringbuf) {
DRM_DEBUG_DRIVER("Failed to allocate ringbuffer %s\n",
ring->name);
- i915_gem_object_ggtt_unpin(ctx_obj);
+ if (is_global_default_ctx)
+ i915_gem_object_ggtt_unpin(ctx_obj);
drm_gem_object_unreference(&ctx_obj->base);
ret = -ENOMEM;
return ret;
@@ -1841,7 +1887,8 @@
error:
kfree(ringbuf);
- i915_gem_object_ggtt_unpin(ctx_obj);
+ if (is_global_default_ctx)
+ i915_gem_object_ggtt_unpin(ctx_obj);
drm_gem_object_unreference(&ctx_obj->base);
return ret;
}