In the past 10 years, Linux gaming came from a painful experience to a reality, with competitive performance, smooth experience and even an ArchLinux based handheld device, the Steam Deck. This progress was made possible by the effort of a strong community working in different parts of the stack, from Wine, userspace graphic drivers and finally the kernel. Gaming workloads have been pushing Linux development to tackle bottlenecks and enhancements never seem before. In this talk, we are going to cover the progress made to enhance game performance from the kernel side, current work and next challenges. (c) FOSDEM 2023 4 & 5 February 2023 https://fosdem.org/2023/schedule/event/kernel_fps/

1. Hacking the Linux Kernel
to get moar FPS
André Almeida @ Igalia
FOSDEM 2023
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2. Linux kernel development model
Linux kernel development has no roadmap, people
develop as they need
Use case driven
If no developer/company cares about something, it
will never appear on Linux
People need to push new use cases
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3. Play on Linux
People have been always playing on Linux, but
struggling at times
Some native ports along the years (with some
troubles), notably Source Engine
BioShock Infinite: Proton version way better than
native one
On and off
Slow progress, no clear financial interest
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4. Proton Era
Announced in August 2018 by Valve
Valve paying community developers and
consultancies to enhance Linux gaming
Linux, Mesa, Wine, DirectX translation layers, etc
Big speed up
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5. Proton Era
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6. Proton Era
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7. Kernel features
Linux gaming has pushed kernel development to new
use cases
Other uses benefits from this as well, mainly desktop
Linux
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8. Kernel features
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9. Filesystem
Case insensitivity in ext4
Then supported at F2FS
Unicode subsystem
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10. Futex
futex is used for userspace mutex, semaphores, etc
Wait on multiple futexes (WaitForMultipleObjects)
futex2
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11. Syscall user dispatch
Use a different "backend" for syscalls in a memory
region
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12. GPU driver
Numerous bugfixes, documentation, and
improvements in DRM drivers, like amdgpu
New DRM features (async page flip in atomic, better
GPU reset handling)
HDR, 3D LUT
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13. Error handling/crash report
Graphical kernel panic ("Windows blue screen")
Pstore and kdump on SteamDeck
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14. Hardware enablement
Support for Steam Deck drivers
Joysticks, controllers
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15. Many bug fixes and
improvements
Split lock detector handling
HID bottleneck for VR use case
Unix sockets, TSC, PTE, timestamps
Panic refactor
Lots of documentation
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16. Out of tree
Task schedulers (PDS, MuQSS)
A lot of work-in-progress patches
https://xanmod.org
https://liquorix.net
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17. What's Next?
Power management
Layers and layers of GPU abstraction
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18. Patches
Case-insensitive
futex2
Syscall user dispatch
https://lore.kernel.org/all/20181206230903.30011
-1-krisman@collabora.com/
https://lore.kernel.org/all/20210915140710.596174
479@infradead.org/
https://lore.kernel.org/all/20201127193238.821364
-1-krisman@collabora.com/
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19. Patches
Split lock
GPU reset:
and
https://git.kernel.org/pub/scm/linux/kernel/git/tor
valds/linux.git/commit/?id=727209376f49
https://lore.kernel.org/amd-gfx/20221125175203.5
2481-1-andrealmeid@igalia.com/
https://lore.kernel.org/dri-devel/20230123202646.
356592-1-andrealmeid@igalia.com/
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20. Patches
HID mutex bottleneck:
More precise info on PTE:
Panic notifier:
https://lore.kernel.org/all/20211130132957.8480-1
-andrealmeid@collabora.com/
https://lore.kernel.org/all/20230202112915.86740
9-1-usama.anjum@collabora.com/
https://lore.kernel.org/all/20220819221731.48079
5-1-gpiccoli@igalia.com/
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