Source
- URL: https://x.com/NOTimothyLottes/status/1687062786273062912
- Author: NOTimothyLottes (@NOTimothyLottes)
- Posted: 2023-08-03 11:28:07
Thread
1/ @NOTimothyLottes
SPC: Using 8 deep swap all aliasing same BO (image) fixes Game Mode crash with external display. Pipelined load gets to black screen in 2 ms. Takes 460 ms to allocate 4 GiB GTT video ram, 558 ms to copy 256 MiB cart from page cache to USWC (page faults), all in parallel.
2/ @NOTimothyLottes
Clearing page cache to simulate a cold launch: Takes 1.5 sec to read 256 MiB from the stock SSD. This is worst case load time in desktop mode. Won’t be any compile/etc after this. So literally in game at this point. Speed of light. This is how it is done.
3/ @NOTimothyLottes
Forgot the timing capture … Load from SSD.
4/ @NOTimothyLottes
There are only 3 threads on load: (1.) to open X11 then spin doing present/keyboard, (2.) to open the AMDgpu device, SDMA copy after CART read, and then eventually spin doing dispatchs, (3.) one to load the CART from disk to mapped USWC GTT via read().
5/ @NOTimothyLottes
Something I don’t know: does read() since it’s kernel- side automatically get some multi-core parallelism? Not a good idea to manually thread the read() because SSD needs linear reads to be fast. Not possible to know if the reads are page cache hits in advance either …