mirror of https://gitee.com/openkylin/linux.git
c8d4c0d668
When PPGTT support was originally enabled, it was only designed to support 1 PPGTT. It therefore made sense to simply hide the GGTT space required to enable this from the drm_mm allocator. Since we intend to support full PPGTT, which means more than 1, and they can be created and destroyed ad hoc it will be required to use the proper allocation techniques we already have. The first step here is to make the existing single PPGTT use the allocator. The astute observer will notice that we are reserving space in the GGTT for the PDEs for the lifetime of the address space, and would be right to question whether or not this is a good idea. It does not make a difference with this current patch only the aliasing PPGTT (indeed the PDEs should still be hidden from the shrinker). For the future, we are allocating from top to bottom to avoid using the precious "gtt space" The GGTT space at that point should only be used for scanout, HW contexts, ringbuffers, HWSP, PDEs, and a couple of other small buffers (potentially) used by the kernel. Everything else should be mapped into a PPGTT. To put the consumption in more tangible terms, it takes approximately 4 sets of PDEs to equal one 19x10 framebuffer (with no fancy stride or alignment constraints). 3/4 of the total [average] GGTT can be used for PDEs, and hopefully never touch the 1/4 that the framebuffer needs. The astute, and persistent observer might ask about the page tables which are also pinned for the address space. This waste is unfortunate. We use 2MB of memory per address space. We leave wrapping the PDEs as a real GEM object as a TODO. v2: Align PDEs to 64b in GTT Allocate the node dynamically so we can use drm_mm_put_block Now tested on IGT Allocate node at the top to avoid fragmentation (Chris) v3: Use Chris' top down allocator v4: Embed drm_mm_node into ppgtt struct (Jesse) Remove hunks which didn't belong (Jesse) v5: Don't subtract guard page since we now killed the guard page prior to this patch. (Ben) v6: Rebased and removed guard page stuff. Added a chunk to the commit message Allow adding a context to mappable region v7: Undo v3, so we can make the drm patch last in the series Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> (v4) Signed-off-by: Ben Widawsky <ben@bwidawsk.net> squash: drm/i915: allow PPGTT to use mappable Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> |
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