iris
3c7d3db370
Changing any primitive re-uploaded every primitive. Measured over the bench fixture by the new arena_churn rig: 758 MB across a fling and 1.2 GB across 401 streamed deltas, p50 3.0 MB per streamed frame. Three separate things were wrong, and only the first is what it looked like from the outside. ArrBuf reallocated on every length change. A fresh Buffer's contents are undefined, so adding one glyph -- which a streamed reply does constantly -- forced a full rewrite, and no partial upload could have been correct in the first place. It has a capacity now, growing geometrically and never shrinking, and update() answers whether the Buffer identity moved so a caller can rebuild its bind group and force the whole range dirty. That alone took the glyph array from 95% re-uploaded to 3%, and stopped primitive_group being rebuilt on every frame the arena changed. A redraw freed its primitives and pushed new ones. Freed slots are not reusable until the end of the frame -- a layer's draw order still names them -- and Painter::draw_twice is how a container learns a child's size, so with containers nested the arena's high-water was the transient push count rather than the live one: 17 million pushes across 401 deltas, 127,443 slots for 11,569 live primitives, growing linearly with the transcript. A redraw now gets its old handles back as a recycle pool (Painter::take_recycled, Primitives::recycle) and writes into the slots it already holds; the pool is consumed in order and whatever the draw does not claim is freed when it ends. The arena is exactly the live count now. The CPU frame improved with it, from p50 2.20ms to 1.39ms on the stream run, because the freeing and the draw-order renumbering went away. Nothing tracked which entries changed. util::Dirty is a bitset per uploaded array, coalesced into ranges at a 1 KiB gap. Marking is O(1) and allocation-free; reading it back is one word per 64 entries. Both alternatives were measured and rejected: a min..max span is nearly the whole buffer, since a frame's changes land in 5-20 scattered runs, and a Vec of indices would mean an allocation and a sort per frame at several thousand marks. It replaces Primitives::updated -- one bool that covered the instances and the per-primitive data together, so rewriting a rect's region re-uploaded every glyph -- and TrackedArena::changed. The trap only the rig could catch: writing an entry is not changing it. Recycling rewrote every glyph of every moved row with identical bytes, marking 73% of the glyph array against 0.6% genuinely changed, because what moves is the instance's region and not the glyph. PrimitiveVec::set and Primitives::set_instance compare before marking. Every array now uploads within a hair of its floor: fling instances 3.4% against 3.3%, fling glyphs 0.9% against 0.8%, stream glyphs 0.6% against 0.6%. Stream instances are at 72.7%, which *is* the floor and is a layout question rather than an upload one -- the list is pinned to the newest end, so a growing reply moves every row, and that should be one move_offsets write rather than a redraw. Noted in RUST.md as the next thing. Also: draw_inner's four old_* parameters become one Retained struct, so the recycle pool is a field rather than an eleventh positional argument next to three others of the same shape; and free_primitive is the one place a slot and its draw-order position are retired together. The rigs move to scripts/rigs/ui-profile, a crate of their own so a rig's dependencies stay out of the app's -- arena_churn needs bytemuck, which nothing in ai-app does. arena_churn prints floor, uploaded and whole side by side per array, because any two of those alone are misleading and the 122x over-marking above was invisible until all three were on screen together.
12 lines
661 B
TOML
12 lines
661 B
TOML
# iris needs nightly (see the #![feature] list in core/src/lib.rs and src/lib.rs).
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# The pin is dated rather than "nightly" because the const-traits feature set
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# changes shape between nightlies: on 2026-09-04 the vendored January tree would
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# not parse at all, because `impl const Trait for T` had become
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# `const impl Trait for T`. A rolling channel turns that into a build that
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# breaks unattended on whatever machine Dev Updater happens to build on.
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# Advance this deliberately, with the feature list in RUST.md's I0b.
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[toolchain]
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channel = "nightly-2026-09-03"
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components = ["clippy", "rustfmt"]
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targets = ["aarch64-linux-android", "x86_64-linux-android"]
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