Beam synchronization issue report (Yosemite VM)

Discussion in 'macOS Guest OS Discussion' started by fredrik, Nov 21, 2015.

  1. fredrik

    fredrik Bit Poster

    To the developers of Parallels Desktop 11:

    I installed a Yosemite VM in Parallels Desktop 11 (running in El Capitan) just recently with the following hardware config:
    Faster Virtual Machine, Enable Adaptive Hypervisor checked, Better performance, Real-time virtual disk optimisation unchecked.
    Processors: 2
    RAM: 2048 MB
    Graphics: 128 MB
    Hard disk size: 30 GB

    Installed OS X Yosemite, installed the Parallels Tools, rebooted. The VM was incredibly sluggish and had input lag when typing and felt very slow. Scrolling a website in Safari was stuttering a lot. I assumed something was up with the graphics bit of things, primarily.

    So, I started googling, and it turns out that VMWare Fusion users are also experiencing stuttering and sluggishness in their Yosemite VMs. And one user had posted in their forum about this suspicious application called "Beamoff". Since it's a VM, I figured I could give it a shot although the risk of downloading a virus or whatever. I downloaded it from this somewhat suspicious file sharing website.

    After having downloaded it, I executed it like this:
    sudo <path-to>/

    ...and voila!
    My Yosemite is now running perfectly fine. There's still stuttering when scrolling a website in Safari, but it's at least much more acceptable now. Typing text and most programmer-related activities now feel acceptable to me (it's a VM after all).

    However... what the heck is this application doing?
    I don't feel comfortable downloading some anonymous application from a file sharing website and running this each time I boot up my VM. So it seems this is in fact doing something you can achieve using the Quartz Debug Developer Tool, outlined here, and which feels much more reliable than using a somewhat suspicious application download from a file sharing website. Also, turns out, the code for the application is indeed open source.

    But so, the root cause of the issue was beam synchronization, which is a technique first introduced in 10.4.x to better handle screen redraw and allow OS X's window management process to be more efficient. Beam synchronization works fine on Yosemite when running on actual machines, but it is apparently a significant issue when running in a VMware VM.

    Could you please look into this issue and perhaps make the Parallels Tools automatically fix this issue, rather than relying on customers figuring this out themselves and going through the trouble of disabling Beam Sync automatically upon boot?

    Some more links:

    I'm awaiting your response.

    Best Regards,
    Last edited: Nov 21, 2015

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