drm/i915/gem: Protect used framebuffers from casual eviction

In the shrinker, we protect framebuffers from light reclaim as we
typically expect framebuffers to be reused in the near future (and with
low latency requirements). We can apply the same logic to the GGTT
eviction and defer framebuffers to the second pass only used if the
caller is desperate enough to wait for space to become available.
In most cases, the caller will use a smaller partial vma instead of
trying to force the object into the GGTT if doing so will cause other
users to be evicted.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210119214336.1463-5-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
index d898b370d7a4faa5f9968fee3dd744de69bc7f18..7b38eee9980f19c5a85aa6659313ac6eeb063f94 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
@@ -225,8 +225,10 @@ static void frontbuffer_release(struct kref *ref)
        struct i915_vma *vma;
 
        spin_lock(&obj->vma.lock);
-       for_each_ggtt_vma(vma, obj)
+       for_each_ggtt_vma(vma, obj) {
+               i915_vma_clear_scanout(vma);
                vma->display_alignment = I915_GTT_MIN_ALIGNMENT;
+       }
        spin_unlock(&obj->vma.lock);
 
        RCU_INIT_POINTER(obj->frontbuffer, NULL);

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index f0379b550dfcb6f25505ea22de30a51d81c5fbd3..a6257314be9cd9c4304d1371c791ff41fd29565e 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -416,6 +416,7 @@ retry:
        }
 
        vma->display_alignment = max_t(u64, vma->display_alignment, alignment);
+       i915_vma_mark_scanout(vma);
 
        i915_gem_object_flush_if_display_locked(obj);
 

diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
index e1a66c8245b859f4c4d710c6cf15eaff8b529472..4d2d59a9942bd01bd39612d155aa64750f016e54 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/i915_gem_evict.c
@@ -61,6 +61,17 @@ mark_free(struct drm_mm_scan *scan,
        return drm_mm_scan_add_block(scan, &vma->node);
 }
 
+static bool defer_evict(struct i915_vma *vma)
+{
+       if (i915_vma_is_active(vma))
+               return true;
+
+       if (i915_vma_is_scanout(vma))
+               return true;
+
+       return false;
+}
+
 /**
  * i915_gem_evict_something - Evict vmas to make room for binding a new one
  * @vm: address space to evict from
@@ -150,7 +161,7 @@ search_again:
                 * To notice when we complete one full cycle, we record the
                 * first active element seen, before moving it to the tail.
                 */
-               if (active != ERR_PTR(-EAGAIN) && i915_vma_is_active(vma)) {
+               if (active != ERR_PTR(-EAGAIN) && defer_evict(vma)) {
                        if (!active)
                                active = vma;
 

diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index 5b3a3c6534540620eef52098ac22102ba5986605..a64adc8c883b01315b41a64a73b8079f533c7191 100644 (file)
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -363,6 +363,21 @@ i915_vma_unpin_fence(struct i915_vma *vma)
 
 void i915_vma_parked(struct intel_gt *gt);
 
+static inline bool i915_vma_is_scanout(const struct i915_vma *vma)
+{
+       return test_bit(I915_VMA_SCANOUT_BIT, __i915_vma_flags(vma));
+}
+
+static inline void i915_vma_mark_scanout(struct i915_vma *vma)
+{
+       set_bit(I915_VMA_SCANOUT_BIT, __i915_vma_flags(vma));
+}
+
+static inline void i915_vma_clear_scanout(struct i915_vma *vma)
+{
+       clear_bit(I915_VMA_SCANOUT_BIT, __i915_vma_flags(vma));
+}
+
 #define for_each_until(cond) if (cond) break; else
 
 /**

diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
index 9e9082dc8f4b9d5c9ecab1e8235577781708035e..f5cb848b7a7ebc1505f4a69fa9531836e7b2fd1a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_vma_types.h
+++ b/drivers/gpu/drm/i915/i915_vma_types.h
@@ -249,6 +249,9 @@ struct i915_vma {
 #define I915_VMA_USERFAULT     ((int)BIT(I915_VMA_USERFAULT_BIT))
 #define I915_VMA_GGTT_WRITE    ((int)BIT(I915_VMA_GGTT_WRITE_BIT))
 
+#define I915_VMA_SCANOUT_BIT   18
+#define I915_VMA_SCANOUT       ((int)BIT(I915_VMA_SCANOUT_BIT))
+
        struct i915_active active;
 
 #define I915_VMA_PAGES_BIAS 24