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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Optimising Ubuntu performance on amd64 architecture (ubuntu.com)

submitted 10 months ago by [email protected] to c/[email protected]

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[–] [email protected] 1 points 10 months ago* (last edited 10 months ago) (1 children)

What do you mean with real-time mode?

I only know of real-time kernels, which allow to measure/calculate the maximum response time of an application. This is important for critical processes, like braking in your car, but decreases performance slightly rather than increase responsiveness.

[–] [email protected] 2 points 10 months ago* (last edited 10 months ago) (1 children)

I mean real-time scheduler, not real-time kernel. Found an article that says kwin_wayland uses SCHED_FIFO.

man 7 sched says:

SCHED_FIFO can be used only with static priorities higher than 0, which means that when a SCHED_FIFO thread becomes runnable, it will always immediately preempt any currently running SCHED_OTHER, SCHED_BATCH, or SCHED_IDLE thread.

but decreases performance slightly rather than increase responsiveness.

Responsiveness is not performance. There are 3 main performance metrics: throughput, latency and jitter. Responsiveness is mostly latency, but sometimes jitter. You can for example run game in 30fps with 0.01s lag or in 60 fps with 1s lag. In second case FPS is higher, but, player will feel game unresponsive because of time it takes between pressing button and game showing the result.

[–] [email protected] 2 points 10 months ago* (last edited 10 months ago)

Thanks for the link, real-time mode definitely makes sense and should be implemented for all compositors imo.

Responsiveness is not performance.

True, I miswrote. What I wanted to write was

but decreases performance slightly ~~rather than~~ in return for an increase in responsiveness.