Booting Windows 7 from a RAMdisk

[Willowwizard]

Had some free time and was bored today.

Admittedly the title is a bit misleading, I had to install Tiny7 because I didn't have the space to install full Windows 7, let alone Windows 10!

It finishes booting in about 10.5 seconds, and is overall incredibly snappy

Strangely, the disk benchmark results are not that impressive

Anyone have any idea why this may be the case? I'm using some bog-standard DDR3 RAM modules at 1067 MT/s, using VirtIO disk bus in the VM.

Could that be the bottleneck? AFAIK it emulates a standard SCSI controller

[Madgemade]

From what I read here this isn't the best way to do what you want. From what I know QEMU is a Emulator first and a VM second. The easiest way to find out the bottleneck would be to use a different VM and see if the disk driver for that works differently. My feeling is that the Emulation aspects of QEMU may be slowing things down IO wise.

 

Something more fun to do would be to install a linux OS itself into a ram disk. I imagine you can set up the initrd to mount a ramdisk, transfer the root filesystem and then mount the disk as root. Then you would be natively running on a ram disk. I imagine it would be pretty quick and totally practical with 32GB+ of RAM. Might be possible to make it persistent by saving changes on shutdown too.

[BeefyMeats]

I just tried win10 in virtualbox with ddr3, and its way worse. I think Im gonna ditch virtualbox now

It was way faster directly on the host.

 

[Willowwizard]

16 hours ago, Madgemade said:

From what I read here this isn't the best way to do what you want. From what I know QEMU is a Emulator first and a VM second. The easiest way to find out the bottleneck would be to use a different VM and see if the disk driver for that works differently. My feeling is that the Emulation aspects of QEMU may be slowing things down IO wise.

 

Something more fun to do would be to install a linux OS itself into a ram disk. I imagine you can set up the initrd to mount a ramdisk, transfer the root filesystem and then mount the disk as root. Then you would be natively running on a ram disk. I imagine it would be pretty quick and totally practical with 32GB+ of RAM. Might be possible to make it persistent by saving changes on shutdown too.

Not sure what you mean by 'an emulator first and a VM second', do you mean software emulation vs hardware emulation? I do have it set up as a KVM (i.e. using VT-x) if that's what you're referring to.

I could probably legitimately do what you're suggesting since, although I only have 12 GB of RAM, a minimal base install of Arch or Gentoo can be pretty tiny
 

2 hours ago, BeefyMeats said:

I just tried win10 in virtualbox with ddr3, and its way worse. I think Im gonna ditch virtualbox now

It was way faster directly on the host.

 

Hmm, I guess VirtualBox has some kind of bottleneck I'm using RAW disk format instead of QCOW2 and such, not sure if that would help though