Why PearPC is SO slow?!

[dadreamer]

Hello!

I'd like to ask this simple question (maybe, it's been already asked here) - why the hell is PearPC so extremely slow on my very fast machine?! My host hardware CPU is Intel Core i7-2600 @ 3.40 GHZ (4 logical + 4 real cores). The PC has 8 Gb of memory, NVidia GeForce GTX 570 video adapter and new SSD with W10 64-bit on it. Initially I tried PearPC 0.5.0 from the distant 2011. The OS installation process was very slow even on generous settings of the emulator (G3 CPU, max amount of DRAM, 50 ms for redraw interval). Then I switched to newer 0.6pre and increased redraw interval to 100 ms. Nothing has changed practically. Well, it became slightly faster but still works 10-15 times slower than the host system.

Now some fun part - I've been installing Mac OS X Tiger 10.4.6 for ~13-14 hours! (took one night + one morning). Ok, when it got installed it's still slow: all file read/write operations are performed at 300-400 kB/sec, the internet speed is limited to this value also. Although video renders without any noticeable delays (and the mouse moves almost without delays), I have to wait for several seconds to several minutes to, say, open Finder, mount .dmg image, copy some file from one folder to another etc. In comparison to PearPC another emulators such as SheepShaver and Basilisk II work much faster - not so fast as the host but I'm almost satisfied with them.

Well, I'm gonna give it up, erase PearPC from my HDD and forget it as a bad dream. But finally I'd like to know if there's something to do with PearPC to speed it up or not.

[kikyoulinux]

Well, it works pretty fast(at least faster than Qemu). It took me one hour or so to install the same os, further more, the disk image was NTFS compressed. My laptop uses an Ivy Bridge i3 processor.

[adespoton]

I've actually found that PearPC is faster than qemu in some areas, and significantly slower in a few. Using Redscorp and/or 0.5 vs qemu 2.8pre, I found that PearPC flew through the boot process, but bogged right down on anything requiring mathematical computations (floating point, etc.) or graphics. Networking is also tricky to set up, and there's no audio; I can get both in qemu.

So PearPC seems to use better disk access routines but worse floating point. Floating point has also been found to be a bottleneck on qemu, so there's probably more going on as well, but I don't know what it is.

[dadreamer]

I hoped that it is somehow related to SSD issues but no - I have just copied all PearPC files to common SATA HDD and launched the OS there. It's still sluggish as a turtle.

To demonstrate my problem w/ PearPC, I recorded a simple video: http://www95.zippyshare.com/v/dM1oe9iD/file.html There you can see that PearPC may be very irresponsive to the user's interaction.

So PearPC seems to use better disk access routines but worse floating point.

I haven't tested floating point operations yet, but as to me the disk management in QEMU is processed faster than in PearPC. I don't know why my situation differs so much though.

[adespoton]

How much memory are you allocating to PearPC? 10.4.6 works best at 512MB IIRC.

Also, what screen resolution are you using? I found on SheepShaver and BII that non-standard resolutions brought things to a crawl -- could be that something similar is happening for you. 1024x768 should be optimal.

[dadreamer]

How much memory are you allocating to PearPC? 10.4.6 works best at 512MB IIRC.

Also, what screen resolution are you using? I found on SheepShaver and BII that non-standard resolutions brought things to a crawl -- could be that something similar is happening for you. 1024x768 should be optimal.

As you might notice on the record, I'm using 1280MB of DRAM and resolution of 1024x768x32. I'll check it with 512MB and other resolutions but I doubt it will change something.

[dadreamer]

Today I've been playing with graphical and memory settings. So, I can conclude that it's not the resolution issue but likely a memory related one. When I set the DRAM to 512 MB, the system becomes more responsive - now the opening of System Preferences takes 3-4 sec instead of 10-15. I found out empirically that 128 to 512 MB is the most comfortable range for the system.

Suddenly it turned out that I cannot increase the memory again to my older values - when I set it to 1280, I'm getting this:



Very interesting! Now I'm unable to set the memory to 512 MB and above, but it's running well on 504 MB and below.

It all doesn't make much sense to me because I switched to SheepShaver and QEMU due to the need of Classic environment. But it may be useful for someone else.

[adespoton]

Hmm... could be to do with where in memory PearPC is allocating memory for the guest OS -- I know SheepShaver has issues with this (but for other reasons than PearPC would). At this point, I'd recommend a reboot of your Windows system, and setting memory to 256MB; that should be enough for 10.4, and is less likely to run into memory addressing issues.

[airat78]

You need to install 10.4 without any updates, any Tiger updates from 10.4.1 to 10.4.11 Significantly slows down emulation. This is PearPC only issue.

[BitGid]

The emulation is quite a bit slower in Windows when compared to Linux/OSX.
Not much you can do. Perhaps try emulating a G3 cpu with -cpu G3
But PearPC is even slower
Cheers, BitGid

[adespoton]

Hmm? I used to run PearPC 0.5 for Windows in WineSkin on OS X because it was significantly faster than running it natively in OS X. This is due to the JIT emulation not working on OS X.

So maybe the issue here is that JIT is disabled?