[Qemu-devel] virtual machine halting and loosing connections

[Qemu-devel] virtual machine halting and loosing connections

[Kyle Hubert]

I've been looking online, but I can't say that I have found the answer
to this yet.

When using QEMU, I've noticed that if I switch away to a different
virtual desktop on the host OS's WM, then QEMU stops what it is doing.
It's really clear when it's in the middle of a boot, but it always
occurs. This causes havoc since I'm using qemu as an ssh client and
the server I'm connecting to drops me for inactivity. This doesn't
matter if I use keepalive or not.

Also, I have noticed that when using the ondemand governor for the
host OS (AMD PowerNow) that QEMU doesn't register for some reason. My
host CPU stays running at 1GHz, when it is capable of 2.6GHz. I can
run anything on the host OS, and I see the cpu freq jump up, so it
works on the host OS. I believe this may have something to do with
kqemu's acceleration.

Thanks for your time.

-Kyle

Re: [Qemu-devel] virtual machine halting and loosing connections

[andrzej zaborowski]

On 28/03/07, Kyle Hubert <khubert@gmail.com> wrote:
> I've been looking online, but I can't say that I have found the answer
> to this yet.
>
> When using QEMU, I've noticed that if I switch away to a different
> virtual desktop on the host OS's WM, then QEMU stops what it is doing.
> It's really clear when it's in the middle of a boot, but it always
> occurs. This causes havoc since I'm using qemu as an ssh client and
> the server I'm connecting to drops me for inactivity. This doesn't
> matter if I use keepalive or not.

Just confirming that I'm seeing the same thing, and it's not a recent
problem because I remember it happening in 0.7.2 and earlier.

Re: [Qemu-devel] virtual machine halting and loosing connections

[Paul Brook]

On Wednesday 28 March 2007 01:22, andrzej zaborowski wrote:
> On 28/03/07, Kyle Hubert <khubert@gmail.com> wrote:
> > I've been looking online, but I can't say that I have found the answer
> > to this yet.
> >
> > When using QEMU, I've noticed that if I switch away to a different
> > virtual desktop on the host OS's WM, then QEMU stops what it is doing.
> > It's really clear when it's in the middle of a boot, but it always
> > occurs. This causes havoc since I'm using qemu as an ssh client and
> > the server I'm connecting to drops me for inactivity. This doesn't
> > matter if I use keepalive or not.
>
> Just confirming that I'm seeing the same thing, and it's not a recent
> problem because I remember it happening in 0.7.2 and earlier.

My guess is it's a bug in your X server, window manager or SDL. If the X 
server stops responding then qemu will stall.

Paul

Re: [Qemu-devel] virtual machine halting and loosing connections

[Kyle Hubert]

On 3/27/07, andrzej zaborowski <balrog@zabor.org> wrote:
> On 28/03/07, Kyle Hubert <khubert@gmail.com> wrote:
> > I've been looking online, but I can't say that I have found the answer
> > to this yet.
> >
> > When using QEMU, I've noticed that if I switch away to a different
> > virtual desktop on the host OS's WM, then QEMU stops what it is doing.
> > It's really clear when it's in the middle of a boot, but it always
> > occurs. This causes havoc since I'm using qemu as an ssh client and
> > the server I'm connecting to drops me for inactivity. This doesn't
> > matter if I use keepalive or not.
>
> Just confirming that I'm seeing the same thing, and it's not a recent
> problem because I remember it happening in 0.7.2 and earlier.

Just to let you and the list know, I downgraded to a 32bit kernel and
it seems to have sorted itself out. Are you running on x86_64?

-Kyle

Re: [Qemu-devel] virtual machine halting and loosing connections

[Rick Vernam]

On Tuesday 27 March 2007 06:34:04 pm Kyle Hubert wrote:
> I've been looking online, but I can't say that I have found the answer
> to this yet.
>
> When using QEMU, I've noticed that if I switch away to a different
> virtual desktop on the host OS's WM, then QEMU stops what it is doing.
> It's really clear when it's in the middle of a boot, but it always
> occurs. This causes havoc since I'm using qemu as an ssh client and
> the server I'm connecting to drops me for inactivity. This doesn't
> matter if I use keepalive or not.

I can say that I do not get this behavior.
Host OS is linux, no-frills Xorg, KDE.
I start up one of my VMs and switch to different desktop...a minute or so 
later I'm able to ssh to that VM - after starting it, I never even visited 
the desktop it's on.

Re: [Qemu-devel] virtual machine halting and loosing connections

[Rick Vernam]

On Tuesday 27 March 2007 08:53:42 pm Rick Vernam wrote:
> On Tuesday 27 March 2007 06:34:04 pm Kyle Hubert wrote:
> > I've been looking online, but I can't say that I have found the answer
> > to this yet.
> >
> > When using QEMU, I've noticed that if I switch away to a different
> > virtual desktop on the host OS's WM, then QEMU stops what it is doing.
> > It's really clear when it's in the middle of a boot, but it always
> > occurs. This causes havoc since I'm using qemu as an ssh client and
> > the server I'm connecting to drops me for inactivity. This doesn't
> > matter if I use keepalive or not.
>
> I can say that I do not get this behavior.
> Host OS is linux, no-frills Xorg, KDE.
> I start up one of my VMs and switch to different desktop...a minute or so
> later I'm able to ssh to that VM - after starting it, I never even visited
> the desktop it's on.

fwiw, I run 64-bit (host) kernel.  all guest stuff is 32 bit.

Re: [Qemu-devel] virtual machine halting and loosing connections

[Kyle Hubert]

On 3/28/07, Rick Vernam <rickv@hobi.com> wrote:
> On Tuesday 27 March 2007 08:53:42 pm Rick Vernam wrote:
> > On Tuesday 27 March 2007 06:34:04 pm Kyle Hubert wrote:
> > > I've been looking online, but I can't say that I have found the answer
> > > to this yet.
> > >
> > > When using QEMU, I've noticed that if I switch away to a different
> > > virtual desktop on the host OS's WM, then QEMU stops what it is doing.
> > > It's really clear when it's in the middle of a boot, but it always
> > > occurs. This causes havoc since I'm using qemu as an ssh client and
> > > the server I'm connecting to drops me for inactivity. This doesn't
> > > matter if I use keepalive or not.
> >
> > I can say that I do not get this behavior.
> > Host OS is linux, no-frills Xorg, KDE.
> > I start up one of my VMs and switch to different desktop...a minute or so
> > later I'm able to ssh to that VM - after starting it, I never even visited
> > the desktop it's on.
>
> fwiw, I run 64-bit (host) kernel.  all guest stuff is 32 bit.

Thanks, I should specify that I am now running the same configuration,
and I no longer have dropouts. Under 64bit(host) and 64bit(guest), I
had the hanging. I don't understand why, since it had happened during
boot, runtime, or shutdown.

-Kyle

Re: [Qemu-devel] virtual machine halting and loosing connections

[WaxDragon]

On 3/27/07, Kyle Hubert <khubert@gmail.com> wrote:

> Also, I have noticed that when using the ondemand governor for the
> host OS (AMD PowerNow) that QEMU doesn't register for some reason. My
> host CPU stays running at 1GHz, when it is capable of 2.6GHz. I can
> run anything on the host OS, and I see the cpu freq jump up, so it
> works on the host OS. I believe this may have something to do with
> kqemu's acceleration.

I have seen the same behavior with cpufreq, but I run the
'conservative' governor on my AMD.  Haven't decided if it's a bug or a
feature yet. ;0)

-- 
22:38 <@WaxDragon> false ^ true
22:39 < false> :(
22:39 < false> dont you think you can XOR me and get away with it! I
always return!

Re: [Qemu-devel] virtual machine halting and loosing connections

[Kyle Hubert]

On 3/28/07, WaxDragon <waxdragon@gmail.com> wrote:
> On 3/27/07, Kyle Hubert <khubert@gmail.com> wrote:
>
> > Also, I have noticed that when using the ondemand governor for the
> > host OS (AMD PowerNow) that QEMU doesn't register for some reason. My
> > host CPU stays running at 1GHz, when it is capable of 2.6GHz. I can
> > run anything on the host OS, and I see the cpu freq jump up, so it
> > works on the host OS. I believe this may have something to do with
> > kqemu's acceleration.
>
> I have seen the same behavior with cpufreq, but I run the
> 'conservative' governor on my AMD.  Haven't decided if it's a bug or a
> feature yet. ;0)

I was running ondemand, and I came to the conclusion it's a bug. If
you see this paper:

http://linux.inet.hr/ols2006_the_ondemand_governor.html

You'll see that the ondemand governor policy is based on the idle/busy
statistics from scheduler ticks. I believe that kqemu runs off of
ioctl's from /dev/kqemu, and perhaps the system call doesn't
accurately change this?

How do the processes run in kqemu? Is it a kernel thread? Section 7.3
in that PDF talks of real time threads affecting the ondemand
scheduler.

NOTE: conservative is a fork of ondemand, so it applies here.

I'll try running without kqemu, and see if I still have the problem.

-Kyle