On Mon, May 8, 2017 at 11:10 PM, Pohjolainen, Topi < topi.pohjolai...@gmail.com> wrote:
> On Mon, May 08, 2017 at 04:51:35PM -0700, Jason Ekstrand wrote: > > On Wed, May 3, 2017 at 2:22 AM, Topi Pohjolainen < > topi.pohjolai...@gmail.com > > > wrote: > > > > > Patches 1-17 are revision that > > > > > > - rework hiz on gen6 to use on-demand offset calculator allowing > > > one to drop dependency to miptree structure and > > > - rework all auxiliary surfaces to be created against isl directly. > > > > > > Patches 18 and 19 introduce new surface layout in ISL. This is called > > > back-to-back and similar to layout ALL_SLICES_AT_EACH_LOD found in > > > i965 for gen6 hiz and stencil. This layout stacks slices for each level > > > after one and other, or back to back. All slices ate each lod is almost > > > the same except that it places levels one and two side-by-side trying > > > to preserve space. Back-to-back wastes a little more memory but aligns > > > each level on page boundary simplifying driver logic. > > > > > > > My primary gripe here is that you seem to have half-added back-to-back to > > ISL. If this layout is a long-term thing, then we should add a new > > ISL_DIM_LAYOUT_GEN6_BACK_TO_BACK layout and plumb your offset function > > through isl_surf_get_image_offset_sa. Is this intended to be a permanent > > solution? I think eventually, I'd like us to go with one surf per > miplevel > > (which is almost the same) but I can see how this is easier at the > moment. > > However, I think this works sufficiently well that I'm ok with doing the > > back-to-back thing for a while. > > I thought about adding new layout type but couldn't decide which way is > better. It is easy to buy your arguments in favor, and I'm happy to give it > a go. > If miptree per level is your number one choice, then lets go with that. I said "one surf per miplevel". I see no reason why we need N miptrees. > I just > need to check a few things first about the actual solution. I would see > something in these lines: > > 1) Add a dynamically allocated array of miptrees into miptree. This would > contain miptree instance per level. > > 2) Still uses one buffer object containing space for all levels. The > instances > in the array would either have their ::bo pointer zero or pointing to > the > parent ::bo. In both cases ::offset would point the start of the level. > Yes > 3) Instances in the array are not reference counted and therefore deleted > simply by deallocating the malloced chunk underneath. > If we have one isl_surf per miplevel and not a miptree per level, then I don't think this is an issue. > 4) Add similar dynamically allocated array of intel_miptree_aux_buffer > instances for hiz. Here also use one ::bo which would need to added to > miptree I think cause there ins't one in miptree. Or perhaps add the > array of aux buffers to aux buffer? > Looking at intel_miptree_aux_buffer, I think what we would end up with is an array of aux_buffers > 5) ISL doesn't need to know about this and hence we would add the total > space > calculator along with ::offset initialization in i965 (brw_tex_layout, > I think). > That's fine. We already do that in Vulkan with anv_surface. ::offset calculation can be done easily enough by just adding sizes. > 6) In Vulkan <-> GL interop, we'd pass single level arrays only as ISL > didn't > know about back-2-back. Or we simply don't care about gen6 as Vulkan > doesn't support it anyhow? > Yeah, we don't care about gen6. --Jason
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