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Cache Full ISO in RAM Question - Printable Version

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Cache Full ISO in RAM Question - nomorevideos - 06-04-2016 04:16 PM

I've tested the "cache ISO in RAM" option with several games (MHFU, MGSPW, 3rd Birthday) and there is no difference between having the option on or off.
I'm using an HDD, so having the full ISO stored in my RAM I should see at least quite a bit of difference, right?

I'm using PPSSPP 1.2.2 for Windows 8.1.


RE: Cache Full ISO in RAM Question - [Unknown] - 06-04-2016 06:07 PM

It's a subtle difference, really.

First off, your operating system will cache the parts of the ISO you access. So if you load the game once, and then try loading with it off and on, it'll be basically the same. After loading it the first time, it'll be coming from RAM, and fast. Your OS says, "you're welcome."

Secondly, if you were playing on a PSP with a UMD, any time it accessed the ISO, you would hear it spin up. And it would be slow. Sometimes special effects do this, but generally games load everything they need for a scene beforehand. So this usually has no impact on in-game performance - just on loading time.

So, then why does the option exist?

Simple. Sometimes people will play a game, fighting enemies or whatever, for long enough that their disk goes to sleep. Then, when they go to a new area, the game has to load new data.... and that is slow, because the disk has to wake up first.

It can also speed up loading a little when the disk isn't asleep yet, but on desktops disks are usually fast enough that this isn't a noticeable difference.

-[Unknown]


RE: Cache Full ISO in RAM Question - nomorevideos - 06-04-2016 08:45 PM

(06-04-2016 06:07 PM)[Unknown] Wrote:  It's a subtle difference, really.

First off, your operating system will cache the parts of the ISO you access. So if you load the game once, and then try loading with it off and on, it'll be basically the same. After loading it the first time, it'll be coming from RAM, and fast. Your OS says, "you're welcome."

Secondly, if you were playing on a PSP with a UMD, any time it accessed the ISO, you would hear it spin up. And it would be slow. Sometimes special effects do this, but generally games load everything they need for a scene beforehand. So this usually has no impact on in-game performance - just on loading time.

So, then why does the option exist?

Simple. Sometimes people will play a game, fighting enemies or whatever, for long enough that their disk goes to sleep. Then, when they go to a new area, the game has to load new data.... and that is slow, because the disk has to wake up first.

It can also speed up loading a little when the disk isn't asleep yet, but on desktops disks are usually fast enough that this isn't a noticeable difference.

-[Unknown]

Oh, ok. Thanks for clearing that up for me.


RE: Cache Full ISO in RAM Question - Avatarass - 06-13-2016 04:20 AM

Wouldn't this feature solve the load lag in GTA games?

Also is there a way to enable this feature in Android?


RE: Cache Full ISO in RAM Question - LunaMoo - 06-13-2016 09:59 AM

@Avatarass any flash memory is already much faster than UMD and also cannot suffer from very specific problems this feature works around when using hdd's, so no it won't be enabled on android, it's pointless and wouldn't help any issue you might have.

I know Rockstar games in general suffer a lot of slowdowns from vertex cache which is enabled by default, so you might try disabling it if you didn't yet, but don't have the game and don't know any "loading lags" it might have. Might just be too heavy for your device or if you can run it at full speed simply load some things slow by design.


RE: Cache Full ISO in RAM Question - [Unknown] - 06-13-2016 12:23 PM

There was a known issue with GTA games on PSP CFW - using a CSO, even on the memorystick duo, caused pretty bad slowdowns. In case you're referring to this, that particular issue is simply due to a bug in CFW, and has never been a bug in PPSSPP at all. I believe it's even fixed in recent CFW versions.

Many people mistakenly think that CSOs are just generally bad for performance due to this CFW bug.

-[Unknown]


RE: Cache Full ISO in RAM Question - Avatarass - 06-14-2016 01:21 PM

(06-13-2016 09:59 AM)LunaMoo Wrote:  @Avatarass any flash memory is already much faster than UMD and also cannot suffer from very specific problems this feature works around when using hdd's, so no it won't be enabled on android, it's pointless and wouldn't help any issue you might have.

I know Rockstar games in general suffer a lot of slowdowns from vertex cache which is enabled by default, so you might try disabling it if you didn't yet, but don't have the game and don't know any "loading lags" it might have. Might just be too heavy for your device or if you can run it at full speed simply load some things slow by design.

Well, I tried disabling vertex cashing, and also loaded the ROM onto internal memory from my USB 3.0 hard drive. It didn't fix the issue. Also I enabled all the speedup hacks, but unsuccessful.

By loading lags I mean the micro freezes that you get when you travel through the city at fast speed, and the game tries to load new assets. It's pretty noticeable, for example, in the second the game loads something the average frame rate will drop go as down as 25, with single large delay between frames somewhere in the middle. I doubt the issue is in the memory, or my device (nvidia shield tv, as fast as it gets).


RE: Cache Full ISO in RAM Question - LunaMoo - 06-14-2016 02:42 PM

Hmm do you have "texture scaling" enabled? If yes, disable it or at least drop it down to a minimum and try xBRZ if you used any other as it's fastest algorithm. That feature only works when new texture get's loaded and so most people might think it's light, however it's actually extremely heavy and what you experience is pretty standard result for people abusing it beyond their hardware limits.


RE: Cache Full ISO in RAM Question - Avatarass - 06-16-2016 03:22 AM

(06-14-2016 02:42 PM)LunaMoo Wrote:  Hmm do you have "texture scaling" enabled? If yes, disable it or at least drop it down to a minimum and try xBRZ if you used any other as it's fastest algorithm. That feature only works when new texture get's loaded and so most people might think it's light, however it's actually extremely heavy and what you experience is pretty standard result for people abusing it beyond their hardware limits.

No, I do not. I wonder whether it's something PSP had by design, but so far I couldn't find any evidence of it, so I have to assume it's due to how the emulation is implemented. Loading the ISO is just one way of trying to fix it, again there's no proof this will help anything (plus I'm sure 90% of PPSSPP users won't be able to load a 1.6Gb image into their RAM). It's more of a debug feature I guess.


RE: Cache Full ISO in RAM Question - LunaMoo - 06-16-2016 04:36 PM

Then probably "as fast as it gets" isn't fast enough and you're just getting slowdowns whenever a lot of new things are processed not when "they are loaded". Vulkan backend will likely help in here once it's done, caching iso to RAM will not.
As a matter of fact games can be broken even by the slowest hdd's speed which is still faster than UMD they expect, hence we need option to simulate umd delays and it does NOT cause slowdowns in any game.


Caching iso is neither a debug nor a performance option, it really only helps on storage with motor that completely stops after certain time on inactivity like power saving hdds(which aren't really all that common) or pretty much every modern CD/DVD/BD drive.
Just for a complete list will also mention a bug happening on Raspberry Pi which could kill IO performance and that's another situation where this option was helping, none of that code ever affected Android nor Windows through and the problem was already fixed.


Apparently all Rockstar games are pretty good at abusing PSP power and so are at least in some places/moments much harder to emulate, you can drop graphic enhancing features down/off(like rendering res or even post processing shaders) or/and use auto frameskip to help it through those more demanding areas.