Frame skip

[JMC47]

I use a branch for netplay that allows us to use Dualcore. While Frameskip doesn't have as large of an effect, it's still a tangible 15 - 25% on computers when it's having trouble maintaining full speed.

The GPU thread is the main bottleneck in most games from what I've seen on IRC. By using Frameskip, you can lessen that bottleneck a bit. Does it mean it won't be the bottleneck? No. Does it mean that the CPU thread won't become the bottleneck very quickly? No. But in a lot of games turning on frameskip is a legitimate way to boost speed even on computers with really good graphics cards.

[Shonumi]

I still have a hard time believing that the GPU thread is frequently the bottleneck in many games, based on personal experience. Out of curiosity, I tried using Frameskipping (in Dual Core mode) on 4.0 in a variety of games. The consistent behavior was that Frameskipping only resulted in a speedup when the GPU thread was bottlenecked. The only instances I could get this to happen where when I forced high IR and AA (4x IR and 4xSSAA for example). In every other instance when I used "normal" graphical enhancements (3x IR and No AA), I didn't see a change in VPS or emulated CPU speed (I ran without framelimits to observe any and all changes in Dolphin's speed). However, in a game like XBC with 4x IR and 4xSSAA, frameskipping yielded a very high VPS and an emulated CPU speed of ~200% (although low FPS due to the skipping).

One thing you might want to look into is if Netplay somehow does something to make the GPU thread a bottleneck. My tests show me that under my "normal" settings for a number of games (non-Netplay btw), it doesn't change anything speedwise when the Framelimit is Off, even when set all the way to 9, so that eliminates the possibility that I'm GPU-bound.

[JMC47]

May just be the games I tend to play. Smash Bros. Melee, Brawl, Fortune Street, NSMBWii, Metroid Prime (ESPECIALLY) as well as others all get significantly sped up for me even at 1x IR!

I don't know what else to say really; I've had good luck with getting speedups via Frameskip being set to 1 or 2.

[Shonumi]

Yeah, at 1x IR, there are definitely no changes for me in VPS in any games that I've tried. The FPS obviously drops, but between a frameskip of 0 and 9, VPS and emulated game speed stay pretty much in the same range. It could be a GPU/driver specific issue, but idk what else to say either :p

[JMC47]

Maybe it's a difference between Windows and Linux? I went through and tested all of my games, and turning on frameskip helped on pretty much every single one.

[Shonumi]

(10-15-2013, 10:04 AM)JMC47 Wrote: Maybe it's a difference between Windows and Linux? I went through and tested all of my games, and turning on frameskip helped on pretty much every single one.

It could be. The OS and the drivers are different. OGL in Linux has usually been faster than on Windows (at least on Nvidia hardware, I think). Nvidia's drivers might be doing something where the GPU thread is processed more quickly on my machine. If I get the time this weekend, I'll try and capture some results.

[MayImilae]

I've done the same testing Shonumi has done, and got the same result on windows. Frameskipping doesn't help unless you crank up the AA and stuff to insane levels.

[JMC47]

MaJoR: Our computers are identical, I find it highly improbable that you get different results than me. I don't know exactly what I could be doing wrong.

I went into Plant Levels of F-Zero GX at stock clock, where there is a slight bit of slowdown on my computer. I drops to 52 fps through some of the turns with frameskip at 0. If I put Frameskip to 1; the VPS remains a solid 60 no matter what, the game only getting choppy when the GPU thread maxes out.

I don't run AA or AF, and only was using 1x IR because my dolphin was setup on Tourney Settings for when I streamed. I really believe no one else has given the option a fair shake.

Edit: Degasus confirmed that I'm not crazy; some stuff in video-common is skipped during frameskip, and said there should be big boosts in games like Super Mario Galaxy.

[anonyme-x22]

Hi,

The game i play use 25 FPS. When i set frame skip to 1, i got 13FPS.
It is possible to have 20FPS (0.5 frame skip) ?
Why the frame skip is slowing down a lot with small value ?

Rgds,

[DJBarry004]

1- Either your CPU or GPU are bad.

2- Afaik, half FPS skip is not implemented yet.

But, I´ve read somewere in the forums that half frame-skip can be controlled (set up) in the configs (not the emulator´s normal menus, the INI files!).