Question about performance impact of rewind

RetroArch General
#1

I was playing with alpha PCSX2 core, and finally got it working faster than 5fps by disabling rewind (tip from a thread on reddit). That specific core aside, I feel as if I’ve run into a similar issue before somewhere a couple years back.

So my question is how much does rewind affect performance, in a general sense? I imagine results vary of course, but would turning it off on lower end machines being some speed improvement in certain types of cores?

I know there are tweaks for the rewind settings, but I don’t fully understand what those settings do/mean for practical use, or on how it impacts system resources.

Wondering if someone can fill me in a bit or point me at a resource for more information.

#2

It varies pretty wildly, but mostly according to the size of the savestate that needs to be made every frame. Bigger states means more of a hit to performance, generally speaking.

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#3

That makes a lot of sense actually, and also explains a lot about how rewind is working in the background.

As for the settings, the granularity makes sense, but what about the buffer size and size step? I get the impression buffer size is how much RAM it allocates to the process, but I’m lost on step for sure.

#4

It changes the amount that the rewind buffer option increments by. For example, at the default setting of 10, the rewind buffer goes 20, 30, 40, …, but if you change it to 11, the rewind buffer goes 20, 31, 42, 53, …

I guess so people can either go to smaller amounts than 10 (like 6MB) or to make getting to very large numbers easier. Dunno, seems kinda silly to me in either case. Just use the config :man_shrugging:

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#5

That makes sense, thank you.

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#6

Can i ask, where can i download the PCSX2 core? It was announced months ago and see others using it but i can’t find it anywhere, at least for Windows.

#7

It’s not released yet, as it’s not yet in a state that we can publicly support. With that said, some people have compiled it themselves from the repo and are passing those builds around.

#8

I got a pre-compiled link from someone on reddit. It’s very much an alpha version. My interest in playing with it early was primarily to play with the core itself, setup my BIOS folders, etc - rather than the games.

SSX Tricky is unplayable in this build, for example (can’t see the ground) Also anytime there’s vibration feedback, I have to open the RA Menu to make it stop, things like that; which are expected with such a build.

Very excited to see the core when it’s finally ready for prime-time though. <3