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Background:

In the past when my guest VM froze, I looked at windows task manager and saw very little ram. This led me to conclude "the host put the VM out of physical memory and into virtual memory (i.e. paging) --> therefore the VM froze because it was now running out of paging instead of physical memory".

Current:

Most recently my guest VM froze and looking at task manager revealed that there was plenty of "available memory" 1.2 GB. I have attached the screenshot of my host windows machine and the guest Fedora 14 VM.

Host task manager and Guest task manager

My observations:

  • the host has plenty of available memory (1.2 GB)
  • the guest has plenty of available memory
  • the screenshot of the guest... is only available because it was by complete chance on the top and visible
  • the host CPU is pegged for 2/4 cores
  • guest CPU is not pegged at all

I closed the VM and my host's task manager showed:

  • physical memory available went up by exactly the same amount of memory allocated to the guest VM
  • paging went went down by exactly the same amount of memory allocated to the guest VM
  • CPU usage went from super high to almost nothing

Given the description, why do you think the guest VM froze? I just can not figure this out and I don't have any debugging tools to see what the problem is!

  • Is there someway to show that the "virtualbox" process is heavily using the hardisk (i.e. the process is in paging now instead of physical memory?
  • How would I show virtual-box is "stuck in paging"?
    • (I have heard of perfmon... but could not figure it out. so please elaborate more than "use perfmon" and say what kind of counters to look at)
share|improve this question
    
@CarlF, I am using VirtualBox version 4.0.8. –  Trevor Boyd Smith Jun 1 '11 at 12:30
    
I would really like to understand how I can use perfmon to investigate the hypothesis of "my vm is having excessive page faults". –  Trevor Boyd Smith Jun 1 '11 at 12:31

2 Answers 2

  1. Check the logs in the Fedora VM to see if anything explains the freeze.

  2. Paging should not be a problem--there's no reason a guest can't page, and paging on the host simply would not freeze the guest.

  3. Please post the version number of VirtualBox you're using. What you are writing about sounds like a VB bug to me rather than any OS problem.

share|improve this answer
up vote 0 down vote accepted

I am now able to do everything I need to do without any freezing in the guest OS.

Here is the configuration that does not freeze:

  • HOST OS: Windows 7 64 bit (Previously: Windows XP 32 bit)
  • HOST OS: 8 GB of available memory (Previously: 3GB in Windows XP 32 bit)
  • GUEST OS: 1 CPUS/core (Previously: 2 CPUSs/cores)
  • HOST OS: VirtualBox version 4.0.8
  • HOST MACHINE: Turned off hyper threading

My gut reaction for "what caused the freezing?". Here are the two credible causes:

  1. I think the lack of memory caused the freezing.
    • The host OS put the guest OS into paging... and then the guest OS didn't technically freeze... it just got really slow.
  2. OR Using 2 cores in the guest OS caused weird freezing in the VM.
    • I think this is much less likely. Because I was using 2 cores (less than the total number of the host machine)... which is well supported feature in VirtualBox.

Unfortunately I did not learn enough about debugging techniques to SHOW which was the TRUE cause... these are just my best guesses.

share|improve this answer
    
I think virtualbox has some weird bug where using multi-core sometimes fails. Pinning all vbox executables to say cpu 0 may help forums.virtualbox.org/viewtopic.php?f=6&t=42721 –  rogerdpack Sep 13 '11 at 18:29
    
thanks for the link to the forums... it always helps to provide a reference =). –  Trevor Boyd Smith Sep 13 '11 at 20:16

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