Re: KVM usability

Dustin Kirkland
2010-03-02T03:02:59Z

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On Mon, 2010-03-01 at 15:59 -0600, Anthony Liguori wrote:
> On 03/01/2010 03:12 PM, Dustin Kirkland wrote:
> > kvm -m 512 -cdrom
> > /home/kirkland/.cache/testdrive/iso/lucid-desktop-amd64.iso -drive
> > file=/home/kirkland/.cache/testdrive/img/testdrive-disk-0086OD.img,if=virtio,index=0,boot=on
> > -usb -usbdevice tablet -net nic,model=virtio -net user -soundhw es1370
> >
> > Among these:
> > * 512MB is a nice step up from the 128MB by default (this one scales
> > based on your hosts memory)
> >
>
> I'm not opposed to bumping from 128M to something else. I'd like to see
> some indication though other than "seems reasonable" as to what the
> value should be. For instance, if a Fedora 12 install doesn't work
> without 256M, that's a solid argument to bump the allocation. Short
> term, I'd like to see this globally configurable.

That would be very nice! I think 256MB (or even 384MB) would be a
reasonable default. Modern Ubuntu LiveCD's will work well with 256MB,
but 128MB is essentially unusable. We should just make sure that the
default is intelligently chosen based on the host's available memory
resources.

The crude logic in testdrive looks like this:

if len(MEM) == 0:
total = commands.getoutput("grep ^MemTotal /proc/meminfo | awk '{print $2}'")
if total > 1000000:
MEM = 512
elif total > 750000:
MEM = 384
else:
MEM = 256

> > * virtio is used for disk and network for nice performance gains
> >
>
> The problem with virtio is that very few OSes have the drivers right
> now. For networking, we can do better, and I've just written a spec for
> a new feature to attempt to address this[1]. For disk, I think we're
> stuck with ide as the default for a long time.

That's safe, reasonable position for upstream to make. And a sane one
for distro's to tweak depending on their intended target guest OS's.

> > * usb device tablet greatly improves the mouse experience
> >
>
> Defaulting usb to on and defaulting to a usb tablet is a reasonable
> thing to do IMHO.

\o/ Definitely a better user experience.

> > * sound card added
> >
>
> This personally would annoy me but if there was wide consensus that this
> was right, I'd be okay with it.

I agree that sound-on by default might be annoying to some. Speaking
for myself, if I don't want to hear guest noises, I usually don't want
to hear host noises either. In which case I mute the sound on my host
and solve both problems. But I don't feel strongly about this one.

> > * qcow2 sparse disk image
> >
>
> This is independent of qemu.

Understood. This merely seemed like the best-practice,
most-recommended, best-performing backing disk format for unwitting kvm
users launching VMs when they don't actually care what the backing
format is.

> > * desktop is 1024 x 720
> >
>
> 1024x768 and this is what the default is today anyway.

Ack.

:-Dustin

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