Qemu's performance is beyond unusable.

[ACoolUsername]

After fooling around a bit, I got Jaguar (10.2) installed. However I noticed it's very slow. I used a stopwatch and found it takes 24 minutes from lanching QEMU to getting to the desktop. Also the disk performance leaves a lot to be desired. I only get about 1 megabyte/second max out of the thing. I changed the CPU emulation to G3, all it did was make the animations smoother. Is there any way to make qemu any faster or do i just have to wait it out? (pun intended)

[adespoton]

What system are you running it on? Which build are you running?

I haven't had those problems since the 2016 builds; the ones done over the past year have added a number of Disk I/O improvements.

Also, which Disk write method are you using? Some are faster than others (there's a thread [or possibly in the mega thread] on here where a bunch of us compare benchmark tests of various write methods, but things have improved significantly since then).

[ACoolUsername]

1: An acer laptop with a 1.8GHz celeron: not exactly fast but it should be enough to do the job.

2: 15 December 2017

3: I honestly don't know, is there any way to check?

[adespoton]

1: That's going to be a tad slow, that extra cache really helps in emulation. Shouldn't make it unusably slow though.

2: That's one of the newer builds with improved Disk I/O.

3: If you don't know, you'll be using the default. Here's some more info:

https://www.qemu.org/2018/02/09/underst ... u-devices/

Here's a discussion of disk performance:

https://wiki.qemu.org/index.php/ToDo/Bl ... nceRoadmap
https://wiki.qemu.org/Features/Qcow3

Instead of using -hda "<drive image>" I tend to use -drive file="<drive image>",format=raw,media=disk -- I think it does essentially the same thing, but with the second method, you can *know* that it's treating it as a raw disk image without any extra steps, because you're explicitly telling qemu what to expect instead of letting it guess. You can also change the media type and add a cache= option for various caching methods. The default is fastest however.

Also, I've heard that the Windows compile of the Dec 2017 QEMU may not be as fast as the Linux and OS X builds.

You could try http://www.open.ou.nl/hsp/downloads3/wi ... 122017.zip and see if it makes a difference.

[edit] also: viewtopic.php?f=34&t=9094

[ACoolUsername]

I tried screamer.exe, and it's still slow as a dog. What's your "secret"?

[adespoton]

My main secret is not using the Windows build, as discussed in the thread I linked, and using a 3GHz processor with plenty of L2 cache and multiple cores :\ Other than that, I mount my drives as block devices instead of as actual files; this allows me to let my host OS manage mounting and unmounting the disk image itself, which lets me use partitioned shadow volumes instead of a flat file. The images are all stored on an SSD, which also helps with disk I/O.

Using QCOW format images will be slower than raw format, so changing the image type won't help you at all on Windows. What some people have done is installed Linux in a VM on Windows and installed Linux QEMU-PPC inside that. They've seen a significant performance boost in doing so.

Something I've been wondering about is now that Windows 10 has a fully functional Linux mode, it should be possible to compile QEMU to run in Linux kernel space with a Windows executable on the front -- I'm not sure if anyone's attempted this yet. It should also theoretically provide speed improvements.

Other than that, one of the things that came up in the other discussion thread is that if you've got Antivirus software on your computer, exclude your image file from scanning. That should cut your reads and writes in half, speeding things up noticeably.

[Cat_7]

Something I've been wondering about is now that Windows 10 has a fully functional Linux mode, it should be possible to compile QEMU to run in Linux kernel space with a Windows executable on the front -- I'm not sure if anyone's attempted this yet. It should also theoretically provide speed improvements.

Qemu can run in W10 Linux. Just compile, and use a VNC viewer

Best,
Cat_7