Help with 'CPU Idle' slider in WinUAE

[antonvaltaz]

Can anyone give me some guidance on the 'CPU Idle' slider in WinUAE? I don't really like fiddling around with CPU settings (prefer to keep things as simple as possible), but I don't like the idea of my old laptop running at 100% CPU for extended periods of time (it gets very hot and the fan gets very loud). Is this not likely to damage my PC?

In some places I've read the target CPU % (with Workbench loaded up but not doing anything) should be at 15%, in other places 30%, in other places just keep it as far as to the left as possible. Which is best? Also, are we talking about the % near the virtual LEDs in WinUAE, or the % in Windows Task Manager? And how limited will this make my emulation experience?

My laptop is an old Dell Inspiron 1501 with a Sempron 3500+ CPU (at 1.8GHz) with 1.5 GB RAM running Windows Vista Home Basic. I am running WinUAE 1.6.1.

[TCD]

About CPU Idle : In the leftmost position you have the highest CPU usage and in the rightmost position the lowest. So you should start with the rightmost position and change it to the left until the emulation runs fast enough for you.

[Ian]

Just stick it all the way to the right.

WinUAE should sort out when it needs more power itself. You might have to change it for the odd game here and there, but I doubt it (Games always use 100% amiga side CPU time anyway so the cpu idle tends not to affect them at all)

[antonvaltaz]

Originally Posted by Ian

Just stick it all the way to the right.

WinUAE should sort out when it needs more power itself.

Sorry if I sound thick, but if that is the case... Why is the slider option there at all? What exactly does it do?

[Ian]

It's for workbench really. Don't know exactly what it does but it does a similar thing to AMD cool and quiet only within the emulation environment.

Without CPU idle WinUAE is always emulating workbench at 100% Amiga speed even if workbench is doing nothing.

[StrategyGamer]

Ian there is something wrong with your analysis because I know for a fact that the CPU Idle slider affects both workbench and games.

[Ian]

I never said it didn't.

I said it's for "workbench really"

It has limited effect during games as they don't tend to idle.

[StrategyGamer]

99% of Amiga games idle. If they didn't idle then a 7 Mhz 68000 game would play wayyyyy to fast on a 50 Mhz 68030.

100% of properly programmed games idle.

[Toni Wilen]

It is very host PC specific setting.

Standard configuration: move right until FPS counter drops then go back few steps. (usually full right results in bad side-effects if it looks ok..)

[Toni Wilen]

Originally Posted by StrategyGamer

99% of Amiga games idle. If they didn't idle then a 7 Mhz 68000 game would play wayyyyy to fast on a 50 Mhz 68030.

Totally wrong. 99% of A500 games are synced to vblank (either via polling or vblank interrupt)

EDIT: perhaps 1% of Amiga games idle

[antonvaltaz]

Originally Posted by Toni Wilen

Standard configuration: move right until FPS counter drops then go back few steps.

Another stupid question: which one is the FPS counter?

[TCD]

Originally Posted by antonvaltaz

Another stupid question: which one is the FPS counter?

When you enable 'On-screen LEDs' it's the third one from the left.

[antonvaltaz]

And it should be at 50fps, yes?

[TCD]

Depends whether it's a PAL game (50) or a NTSC one (60).

[TCD]

Originally Posted by plankton

If keeping it to the far right is the optimal way to use it then why does it stay all the way to the left by default?

'Optimal' to save CPU time, but not necessarily for the emulation itself. Like Toni said the rightmost (or even just a few steps to the right) position can cause side effects, so the most compatible setting is the leftmost.

[NewDeli]

If you want to ease up things a bit for your Sempron, at the cost of some (small) compatibility loss, you might try this :

- Untick More compatible for both CPU & FPU (doesn't apply if Cycle Exact is ticked)


I myself leave the CPU idle slider to the right. Oh, and in case you didn't notice, there is a slider in Quickstart, for setting Compatibility VS CPU that you might try ajusting.

[Toni Wilen]

CPU Idle is/was originally meant to lower CPU usage ~20-40% from 100% (which is does fairly well, 1-2 steps from left) but anything more and there can be serious issues.

[NewDeli]

Originally Posted by Toni Wilen

CPU Idle to lower CPU usage ~20-40% (which is does fairly well, 1-2 steps from left) but anything more and there can be serious issues.

I wasn't aware of that, thanx. All engines left full speed then .

Will it decrease CPU load on a fast machine too ?
(I mean, I am nowhere near 100% CPU usage, not even 50)

[Ed Cruse]

I have a 2GHz dual core AMD and find that halfway on the idle slider works just fine. The device manager shows about 18% for each core when the Amiga is doing nothing. The only real problems I've ever had with the idle being to far to the right has been the sound, it stutters. I haven't messed with the slider since Toni redid the sound part of WinUAE so that might not be an issue now. I'll have to check it out.