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8-post thread on NV-specific 1-deep swap with IMMEDIATE presentation,
after previous AMD-tuned impl stopped working. One descriptor set
always bound (resources static after init). Dropped
VK_DESCRIPTOR_SET_LAYOUT_CREATE_UPDATE_AFTER_BIND_POOL_BIT_EXT
('god awful naming length') to avoid NV indirection perf hit.
2700 lines of engine, embedded headers, one-file compile. 0.25 sec
hot-load on NV dGPU: 4 MiB 'cart' file from pagecache, 512 MiB GPU
buffer, all PSOs, image alloc, command buffer copy+clear. Load-time
parallelism: {instance create, cart map, TLB warming by walking pages,
window bringup} = 0.08 sec. After VK device, signal background SPIR-V
load while building descriptor set layout, then PSO compile
parallel. Earliest documented use of 'cart file' term - 9 months
before the Aug 2025 public announcement.
134 lines
5.2 KiB
JSON
134 lines
5.2 KiB
JSON
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"posts": [
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"post_id": "1858709400791261630",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "Working towards a new bring up of front-buffering on NV via VK. My last implementation had been tuned on AMD and didn't work on NV any more. NV does seem to accept a 1-deep swap with IMMEDIATE presentation at least on latest drivers, so that is a good start.",
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"timestamp": "2024-11-19 03:10:28",
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"post_id": "1858710122727391666",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "Since my image resources are static after init time, only swap images change when the driver kills the swap chain (which once upon a time seemed to happen on ALT+TAB maybe). So it's one descriptor set always bound.",
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"timestamp": "2024-11-19 03:13:21",
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"post_id": "1858710719018979651",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "Stopped using VK_DESCRIPTOR_SET_LAYOUT_CREATE_UPDATE_AFTER_BIND_POOL_BIT_EXT (god awful naming length people), because I think it could be a perf hit on NV due to extra indirection. NV driver is free to bake down the single set now before the command buffer is sent over.",
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"timestamp": "2024-11-19 03:15:43",
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"post_id": "1858712158004994552",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "At this stage, to the point of having everything loaded and swap chain created, it's 2700 lines of engine code. That includes embedding headers (no external includes), so it's a one file compile. People claim rolling your own engine is hard? Not really if you keep it focused.",
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"timestamp": "2024-11-19 03:21:26",
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"post_id": "1858713499716694264",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "So far it's a 0.25 sec hot load time on this NV dGPU laptop. Includes mapping a 4 MiB 'cart' file from pagecache, doing a 512 MiB buffer for GPU usage, hits on all PSOs, allocating some images, and kicking the command buffer that copies in the cart, and clears everything.",
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"timestamp": "2024-11-19 03:26:46",
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"post_id": "1858714108415119495",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "Everything at load-time is multi-threaded to try to minimize start to in-game time. This is in sharp contrast to runtime where the only multi-threading being used is to separate things that are blocking.",
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"timestamp": "2024-11-19 03:29:11",
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"post_id": "1858714908516381114",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "I get some utility on parallelizing {vulkan instance creation, mapping the cart file, warming the TLBs by walking all the pages, bringing up the window} it's about 0.08 seconds in at that point",
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"timestamp": "2024-11-19 03:32:22",
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"post_id": "1858715434436227544",
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"author": "NOTimothyLottes",
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"handle": "NOTimothyLottes",
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"text": "After VK device is open, I signal a background thread to load the SPIR-V module, while building the descriptor set layout, which then unblocks PSO compile on background threads. And the rest of the VK setup runs in parallel. Working towards swap creation.",
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"timestamp": "2024-11-19 03:34:27",
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"source_url": "https://x.com/NOTimothyLottes/status/1858715434436227544"
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