virtualbox.org

Interesting observation and good detective work!
Do you have a log from when you have the ext. display connected so that I can compare them?

Sorry, I didn't get a notification mail for this message = another support case ?
I would create the log file like this: Start the machine in 2560x1440 mode (external monitor), switch to 5K (internal monitor), shut down the machine. Is that enough?

macjacke wrote:I didn't get a notification mail for this message = another support case ?

Are you kidding me? Just because you can't set your preferences right, you're going to raise a ticket!?! Of course not, you're going to end up like the boy who cried wolf if you do that...

You need to go to the User Control Panel » Overview » Board preferences » Edit posting options » Notify me upon replies by default: set that to Yes.

macjacke wrote:I would create the log file like this: Start the machine in 2560x1440 mode (external monitor), switch to 5K (internal monitor), shut down the machine. Is that enough?

No, I don't want to create the log like this. I don't want one log, I want two logs.

One log is where you're running just with the iMac alone. As I said, not full screen, but windowed mode. And not 2560x1440, because that's your HiDPI one: (2560x1440) x2 = 5120x2880.

Then one log where you're running the VM if the external monitor is plugged in.

In both cases, launch the VM, login, shutdown the VM, ZIP and attach the log.

socratis wrote:{...}

macjacke wrote:I would create the log file like this: Start the machine in 2560x1440 mode (external monitor), switch to 5K (internal monitor), shut down the machine. Is that enough?

No, I don't want to create the log like this. I don't want one log, I want two logs.

One log is where you're running just with the iMac alone. As I said, not full screen, but windowed mode. And not 2560x1440, because that's your HiDPI one: (2560x1440) x2 = 5120x2880.

{...}

I generally work in full screen mode.

For the test I like to switch in the window mode. Which window size do you recommend for working with Virtualbox with a 27 inch monitor? Please tell me your recommended window size, e.g. 1/2 width and 1/2 height (notebook size).

I have most (except DOS-based VMs) at 1280x1024. It's like having a document open. When I really need the attention, I go full-screen on one of my two external monitors, which happen to be... 1280x1024

I will use a notebook resolution for the test, so about 1/4 of screen.

Please note that this is not a typical resolution for an iMac. My iMac 2011 already has a resolution of 2560x1440 (2.5K). You can't really work with a notebook window. Have you ever run KDevelop or Visual Studio in such a small window? I occasionally do this with a MacBook Pro 13", which is only possible in an emergency.

Do you understand the difference of moving too many pixels? I don't care particularly about the screen size, I care about the performance issue. So, start small and if you get to full blown full-screen you observe the issue, then we'll know where the problem is.

You don't test drive a car at 20,000 rpm...

socratis wrote:Do you understand the difference of moving too many pixels? I don't care particularly about the screen size, I care about the performance issue. So, start small and if you get to full blown full-screen you observe the issue, then we'll know where the problem is. {...}

To the facts: It's almost impossible to run an iMac 2017 5K with Virtualbox. However, VirtualBox and the iMac 5K can work together with heigh performance. See my test with the 2.5 K iMac monitor.

As a workaround, I wrote a program that allows you to set the 2.5 K resolution on the iMac 5K. Actually two programs, one to switch on the 2.5 K mode and one to switch back to the 5 K mode.

In mode 2.5 K VirtualBox works fast with all systems. Since VirtualBox normally only uses 2.5 K, no optical difference is visible in VirtualBox. On other macOS applications the difference in quality is hardly noticeable. But for the use of Virtualbox I can reduce the resolution and otherwise use the 5 K resolution.

I will use this procedure until a clever programmer has solved the problem inside Virtualbox.

Of course, iMac always displays a full screen with all 5K, 5120 x 2880 (14.745.600 pixels), so it always moves all pixels. But now turbo fast:-).

Have you tried disabling the audio (or using the Null Driver) in VM settings? That greatly improved the performance on my linux guest on macos host.

I had to change my iMac, and ever since I did that my Windows 10 client runs very slowly. It is assigned with 1 out of the 4 core's, and it has 4 GB Ram which should be plenty for Win 10, still it runs very slowly. I have the same configuration on my MacBook with the same settings and there everything is just fine.

Here is the log file of a simple Boot up / Turn off procedure of my Win 10 client, I usually have no problems to set things like that up but in this case I'm helpless. Is there anyone out there who can see a possible reason for this? Thanks a lot in advance

@ cc@gauge...,
I merged your post with an existing of soooooo many topics (and tickets) that talk about that. I picked the most recent one. Please search about the subject before opening a new thread...

00:00:02.109737 GUI: 2D video acceleration is disabled

And so is the 3D acceleration. Shutdown the VM and enable them in the VM settings » Display. You'll also notice that the max VRAM will jump from a max value of 128 to 256 MB after that; max the VRAM as well. Then re-install the Guest Additions (GAs) in the guest.

00:00:01.539126 GUI: UIMachineLogicFullscreen::sltHandleNativeFullscreenWillEnter: Machine-window #0 will enter native fullscreen

And don't use it full screen, use it in a windowed-mode. 5K is a *lot* of pixels to move around on a fake GPU. Especially if 2D/3D acceleration is disabled.

Go give yourself a 2nd CPU, get into windowed mode and go in the VirtualBox Preferences (not the VM Settings) » Display » Scale Factor, set that to 200%. Pick yourself a sensible resolution, something like 1280x1024 and you're going to be fine.

PS. For future reference you should ZIP your logs. It helps you, it helps us, it helps the server, it helps save a (virtual) tree or two...

please excuse this post if your problem is resolved, I had a similar experience and wanted to share the solution that I found (very poor performance on an iMac 2019 i9/Host running a Windows 10 Virtual Machine). After searching the forums I was able to resolve the issue by doing the following :

1. I Installed the VBoxGuestAddions in the Windows 10 VM Client. This massively improved the performance of the graphics and filled to screen when in full-screen mode (rather than displaying a tiny window in the middle of the display). I then had the problem that some of the fonts were corrupt when displaying text. This was solved by the next step (2).
2. Set the Graphics Controller to "VBoxVGA" in the Screen Settings for the Windows 10 Virtual Machine.

Once I had done this, the virtual machine runs fine also in Full-Screen mode with more than acceptable performance (I have allocated 4GB and 4Cores to the VM).

@duesseltal, thanks for the info, but...

duesseltal wrote:on an iMac 2019

My notes (actually Mactracker's notes) indicate that the latest iMac is from 2017, can you please explain that? Go to the Apple icon (top left), click "About this Mac" » "System Report..." » "Model Identifier".