USB2 is five times slower than native on qemu-kvm

[Toddandmargo-n]

Dear Qemu,

Spice told me to report this over here.

Scientific Linux 6.6

$ uname -r
2.6.32-504.16.2.el6.x86_64

$ cat /etc/redhat-release
Scientific Linux release 6.6 (Carbon)

$ rpm -qa qemu\*
qemu-img-0.12.1.2-2.448.el6_6.3.x86_64
qemu-kvm-0.12.1.2-2.448.el6_6.3.x86_64

I have a bootable USB2 FC21 flash drive. I can boot my machine directly from it or run it as a virtual machine through KVM.

Problem: it is about 5 times slower through KVM. (Really, I am not exaggerating)

Many thanks,
-T

[Michael Tokarev (mjt+launchpad-tls)]

That version was a pre-alfa version of kvm support in qemu, is insanely outdated, is heavily patched by redhat. I don't even think USB2 was supported by that version. Please try on a current version of qemu and kernel and reopen if the problem persist there.

[Toddandmargo-n (toddandmargo-n)]

On 05/23/2015 01:08 AM, Michael Tokarev wrote:
> That version was a pre-alfa version of kvm support in qemu, is insanely
> outdated, is heavily patched by redhat. I don't even think USB2 was
> supported by that version. Please try on a current version of qemu and
> kernel and reopen if the problem persist there.
>
> ** Changed in: qemu
> Status: New => Invalid
>

Hi Michael,

Thank you for your consideration. I had a feeling.

I asked Red Hat if they would have a whack at it.
They are suppose to support EL6 till 2020, but they
really don't. So maybe.

I am trying to upgrade to EL7, but the lack of Wine32
support is a deal killer.

Just out of curiosity, does the USB support work any better
in the new version of qemu? Is it "on the fly" or do you
still have to map each drive in?

Many thanks,
-T

--
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Computers are like air conditioners.
They malfunction when you open windows
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