From: Chris Wilson Date: Wed, 23 Dec 2020 12:20:50 +0000 (+0000) Subject: drm/i915/gt: Prefer recycling an idle fence X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d7d82f5d5c04ed9cb68d3663ffde10898a2969be;p=linux.git drm/i915/gt: Prefer recycling an idle fence If we want to reuse a fence that is in active use by the GPU, we have to wait an uncertain amount of time, but if we reuse an inactive fence, we can change it right away. Loop through the list of available fences twice, ignoring any active fences on the first pass. Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20201223122051.4624-1-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c b/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c index 7fb36b12fe7a2..a357bb4318152 100644 --- a/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c +++ b/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c @@ -320,13 +320,31 @@ void i915_vma_revoke_fence(struct i915_vma *vma) fence_write(fence); } +static bool fence_is_active(const struct i915_fence_reg *fence) +{ + return fence->vma && i915_vma_is_active(fence->vma); +} + static struct i915_fence_reg *fence_find(struct i915_ggtt *ggtt) { - struct i915_fence_reg *fence; + struct i915_fence_reg *active = NULL; + struct i915_fence_reg *fence, *fn; - list_for_each_entry(fence, &ggtt->fence_list, link) { + list_for_each_entry_safe(fence, fn, &ggtt->fence_list, link) { GEM_BUG_ON(fence->vma && fence->vma->fence != fence); + if (fence == active) /* now seen this fence twice */ + active = ERR_PTR(-EAGAIN); + + /* Prefer idle fences so we do not have to wait on the GPU */ + if (active != ERR_PTR(-EAGAIN) && fence_is_active(fence)) { + if (!active) + active = fence; + + list_move_tail(&fence->link, &ggtt->fence_list); + continue; + } + if (atomic_read(&fence->pin_count)) continue;