CPU usage remains higher when you return to normal speed from unthrottle

[tywald]

What happens?

I didn't pay attention to this issue before(if there was) but seems to happen on all PPSSPP versions I tried(1.3-1.6.3).

When you unthrottle/toggle alternative speed(unlimited) for about 5 seconds then return to normal speed the CPU usage remains higher than before you sped up. It will go back down if you pause emulation then resume.
I've activated Intel SpeedStep so the CPU won't run at max frequency all the time unless there is enough load but with this issue it seems to stay at max until you pause then resume.

It's caused by enabling "Force real clock sync (slower, less lag)".

What should happen?

The CPU usage should return to the same level prior to speeding up.

What hardware, operating system, and PPSSPP version? On desktop, GPU matters for graphical issues.

CPU: i7-3770K.
GPU: GTX 680.
OS: Windows 10 Home 64-bit.
Seems to happen on all PPSSPP versions I tried(1.3-1.6.3).

[unknownbrackets]

This could easily be driver heuristics and might also depend on settings. On Windows 7 / i7-3770, my CPU has definitely spun down after releasing unthrottle (not immediately, the driver waits a bit) for a very long time.

I'm not sure there's any way for PPSSPP to control this behavior. If it's related to your GPU or GPU driver, you could try enabling FrameskipUnthrottle in ppsspp.ini. I have a 950.

-[Unknown]

[tywald]

Ah I should have tested with a fresh config, it doesn't happen anymore with one. Let me go through and find what setting caused it.

Looks like it's caused by enabling "Force real clock sync (slower, less lag)".
Yeah I can consistently reproduce it with it enabled, turning it off fixes it.

[hrydgard]

Ah, that one makes some sense that it could cause something like this.

[unknownbrackets]

That uses spin locks on Windows (since Windows is embarrassingly incapable of sleeping for < 1ms, unlike Linux, Macs, and dinky little PSPs) - I would expect it to use higher CPU usage always, not just after unthrottling.

-[Unknown]

[unknownbrackets]

#11813 fixes this, but possibly not in the way expected. The setting was not working all the time.

After the fix, the setting will cause consistently high CPU usage but also hopefully correctly synchronize for networking (if you have a sufficiently low latency connection) and input lag reasons.

-[Unknown]