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sarah-walker-pcem / pcem

PCem
http://pcem-emulator.co.uk
GNU General Public License v2.0
1.55k stars 216 forks source link

PCem V17 GA-686BX slow when entering folders #215

Open Fighting975 opened 1 year ago

Fighting975 commented 1 year ago

When I selected motherboard as GA-686BX and installed OS like Windows 98 SE or Windows ME, I noticed that everytime I enter a folder from "My Computer", PCem can be slow for a short while to 50%~70% and recover to 100% soon, why is that? CPU I selected is Pentium II 450Mhz

unreal9010 commented 1 year ago

That's because you selected a (slightly) "too fast" processor to be emulated and your host CPU cannot handle it properly due not being able to deliver enough power for such emulated CPU. Try selecting a slower CPU. For example, I've got 12900KF and speed is always at 100% when opening folders or navigating through Windows Explorer as long as I don't go above Pentium II 350 Mhz. Of course, PCem also has some compiler/dynarec-related regressions, however, none of them are related to Windows Explorer.

Fighting975 commented 1 year ago

Thank you for the reply! My host CPU is i7-13700k, and I'm going to try "slow down" the selected cpu XD

unreal9010 commented 1 year ago

13700K is a very capable processor and its ST performance is about 5% faster than that of my 12900KF, meaning emulation of Pentium II 400 should be at stable 100% most of the time, although Pentium II 350 would be a much safer bet for a rock-solid 100% performance with this processor. Currently, there is no CPU available that would be able to handle Pentium II 450 emulation at 100% the whole time.

leilei- commented 1 year ago

On a real machine the shell's slow too. Microsoft aggressively pushed HTML in Explorer around this time (an IE4 cruft feature).

megadora commented 1 year ago

This does actually seem to be a PCem performance issue.

I replicated it on GA-686BX ranging from PII-233 to PII-450. My host is an i7-12700.

It only occurs if the folder view is set to web style (not classic). By default, I think "My Computer" will display web style. My Windows Explorer was not set to web style at first, so I was confused as to why it was only happening in My Computer, but when I enabled web style it happened in Windows Explorer too.

Regardless of guest CPU, when I navigate folders, there is a slight drop in emulation speed, visible in PCem's machine status window with speed history enabled. I think this is on top of the actual slow web style shell, and I suspect the emulation slowdown is so small that it isn't really perceptible, but it's there according to the emulation speed history.

OP: By the way, with a i7-13700k, you should be able to run quite a few programs on a PII-400 or PII-450. Just do a bit of experimenting and keep an eye on the emulation speed.