Benchmarking The Ubuntu "Low-Jitter" Linux Kernel

[Paradox Ethereal]

You get 60fps on a standard ubuntu kernel? Without jitter? No small jitter on startup of doom3 even? Then there are definately differences somewhere I am not aware of. Do note that I want it to run completely perfectly. Not even small jitter on startup. No lost frames at all. No "jerking" AT ALL.

I think I wrote most of the changes I did here: http://paradoxuncreated.com/Blog/wordpress/?p=2268

Quake live is a less complex engine, and seems to have little problem with jitter. It is probably the less rare jitter you want out of that.

Anyway I am thinking about jitter and latency.

Do you think Rob Hubbard did much buffering here? http://www.youtube.com/watch?v=XetgpWY7WOg

Some games who used digitized audio though, seems to play it with low latency. Imagine win95 later, some cards have 150ms latency, and here a 1mhz c64 plays it without latency. There has to be some wrong programming paradigm somewhere.

Peace Be With You.

[WorBlux]

But the benchmark does include a standard error. And, looking at the full results, it does show that the low jitter kernel usually reduces it, but the difference is very slight. On Prey it seems to make the largest difference of 0.06 FPS smoothing while eating 0.36 FPS. On the other hand, with Ultra quality Xonotic, it makes everything worse, both the framerate and smooth framerate.

We want deviation measured from one frame to the next within a single benchmark, not one benchmark run to the next.

[Kano]

@Paradox Uncreated

I don't fully get what you mean by jitter. When you think of loading assets for the first time you certainly get a delay - that has got nothing to do with the kernel. Even on my ssd i get slighly different benchmarks when using timedemo for the first time. How on earth do you get your values?!

[NomadDemon]

please... make theese tests again.. with point.. not with just fps in games

same stuff was with first SLI stuff. micro-stutering

fps was higher, but there was lags ever frame

[devius]

No small jitter on startup of doom3 even? Then there are definately differences somewhere I am not aware of. Do note that I want it to run completely perfectly. Not even small jitter on startup. No lost frames at all. No "jerking" AT ALL.

I think that on startup it's actually the disk I/O operations taking precedence over the graphical operations (please feel free to replace non-tech words with the correct terms) so of course there will be some slowdowns on screen updates. It's a matter of priority. You'll be amazed how much of what you call jitter will go away with a SSD. You should also be looking at ways of increasing the priority of graphical and user input operations vs disk I/O operations. That's what Google is trying to do with the newer versions of Android (4.1+).

[GreatEmerald]

We want deviation measured from one frame to the next within a single benchmark, not one benchmark run to the next.

Oh, yes, you're right. Making that information available shouldn't be difficult to implement...

[Paradox Ethereal]

I think that on startup it's actually the disk I/O operations taking precedence over the graphical operations (please feel free to replace non-tech words with the correct terms) so of course there will be some slowdowns on screen updates. It's a matter of priority. You'll be amazed how much of what you call jitter will go away with a SSD. You should also be looking at ways of increasing the priority of graphical and user input operations vs disk I/O operations. That's what Google is trying to do with the newer versions of Android (4.1+).

Well a lot of people believe that and maybe even an SSD helps. But what would you say if I am running completely without those lost frames?

Peace Be With You.

[Paradox Ethereal]

Btw x-servier is also a performance bottleneck, and introduces jitter.

sudo schedtool -p 98 -n -20 -F `pgrep X`

Also updated my page with that.

Peace Be With You.

[ArchLinux]

Peace Be With You.

Why? Why? Why?

[Kano]

@Paradox Uncreated

You completely disable composite in your instructions on your page. I don't think that will help any u unity user. KDE would still work that way but basically it is enough when you run off the effects when you play games or videos. Basically your nick is somehow "right", what you do is really "paradox". Your tuning efforts are completely out of control. It is impossible that you can get rid of disk io related issues with just increasing the priority for X. Where should the new data magically appear? If you play games that buffers everything at level start then you don't see that effect of course. When you look at rage - which can be run with wine as well (use: winetricks xact_jun2010 directx9) you will see an example that loads all the time textures from hd. Best get yourself a ssd and try it without your hacks. Next time you say when you run a copy process in the background that you can not play correctly. I personally think that your hacks for doom3/prey are overkill for most gfx cards - until you get really fast ones and should be never used.