Re: [Qemu-devel] Monitoring Screen Activity in QEMU/KVM

Re: [Qemu-devel] Monitoring Screen Activity in QEMU/KVM

[Claudio Fontana]

Shehbaz Jaffer wrote:

> I want to determine the amount of screen activity taking place on VGA monitor/ Screen for different applications (eg. playing vlc video, normal typing.)
> 
> When I do not start the X server, I can easily determine the screen activity by counting the number of pages accessed in the region 0xA0000 - 0xBffff (This is the VGA Monitor region in boot screen).
> 
> However when I start the X Server, A diffrent set of pages are hit. Could anyone please explain how the VGA Monitor works in QEMU? Or if someone could suggest an alternate solution to determine amount of screen activity while playing diffrent applications?
> 
> [NOTE : I have already checked for the region where X server pages are mapped using cat /proc/iomem. But pages are not getting written to the "possible" X server mmapped region.]
> 
> Regards,

If you define "screen activity" = "number of pages accessed in the range 0xa0000-0xbffff per unit of time", you could keep your thing going by just using the generic "vga" driver in your Xorg configuration, and that would keep your model valid I think.

Claudio

Re: [Qemu-devel] Monitoring Screen Activity in QEMU/KVM

[Anthony Liguori]

Claudio Fontana <claudio.fontana@huawei.com> writes:

> Shehbaz Jaffer wrote:
>
>> I want to determine the amount of screen activity taking place on VGA monitor/ Screen for different applications (eg. playing vlc video, normal typing.)
>> 
>> When I do not start the X server, I can easily determine the screen activity by counting the number of pages accessed in the region 0xA0000 - 0xBffff (This is the VGA Monitor region in boot screen).
>> 
>> However when I start the X Server, A diffrent set of pages are hit. Could anyone please explain how the VGA Monitor works in QEMU? Or if someone could suggest an alternate solution to determine amount of screen activity while playing diffrent applications?
>> 
>> [NOTE : I have already checked for the region where X server pages are mapped using cat /proc/iomem. But pages are not getting written to the "possible" X server mmapped region.]
>> 
>> Regards,
>
> If you define "screen activity" = "number of pages accessed in the
> range 0xa0000-0xbffff per unit of time", you could keep your thing
> going by just using the generic "vga" driver in your Xorg
> configuration, and that would keep your model valid I think.

Pretty sure the vga driver will use VESA interfaces and the VESA BIOS
will use PCI bar mapping.

You could also trap accesses to where the BAR gets mapped on the PCI
device.  Far better to just register a DisplayChangeListener though and
let QEMU do the heavy lifting.

Or use VNC as Richard mentioned elsewhere.

Regards,

Anthony Liguori

>
> Claudio

Re: [Qemu-devel] Monitoring Screen Activity in QEMU/KVM

[Claudio Fontana]

> Claudio Fontana <address@hidden> writes:
> > Shehbaz Jaffer wrote:
> >
> >> I want to determine the amount of screen activity taking place on VGA
> >> monitor/ Screen for different applications (eg. playing vlc video, normal
> >> typing.)
> >>
> >> When I do not start the X server, I can easily determine the screen activity
> >> by counting the number of pages accessed in the region 0xA0000 - 0xBffff
> >> (This is the VGA Monitor region in boot screen).
> >>
> >> However when I start the X Server, A diffrent set of pages are hit. Could
> >> anyone please explain how the VGA Monitor works in QEMU? Or if someone could
> >> suggest an alternate solution to determine amount of screen activity while
> >> playing diffrent applications?
> >>
> >> [NOTE : I have already checked for the region where X server pages are
> >> mapped using cat /proc/iomem. But pages are not getting written to the
> >> "possible" X server mmapped region.]
> >>
> >> Regards,
> >
> > If you define "screen activity" = "number of pages accessed in the
> > range 0xa0000-0xbffff per unit of time", you could keep your thing
> > going by just using the generic "vga" driver in your Xorg
> > configuration, and that would keep your model valid I think.
>
> Pretty sure the vga driver will use VESA interfaces and the VESA BIOS
> will use PCI bar mapping.

you are thinking of the generic 'vesa' driver:
http://cgit.freedesktop.org/xorg/driver/xf86-video-vesa/

There is also a generic 'vga' driver:
http://cgit.freedesktop.org/xorg/driver/xf86-video-vga/

That said, I was being semi-serious: an Xorg running on plain vga
driver is hardly a realistic use-case.

> You could also trap accesses to where the BAR gets mapped on the PCI
> device.  Far better to just register a DisplayChangeListener though and
> let QEMU do the heavy lifting.
>
> Or use VNC as Richard mentioned elsewhere.
>
> Regards,
>
> Anthony Liguori
>
> >
> > Claudio

[Qemu-devel] Monitoring Screen Activity in QEMU/KVM

[Shehbaz Jaffer]

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I want to determine the amount of screen activity taking place on VGA
monitor/ Screen for different applications (eg. playing vlc video, normal
typing.)

When I do not start the X server, I can easily determine the screen
activity by counting the number of pages accessed in the region 0xA0000 -
0xBffff (This is the VGA Monitor region in boot screen).

However when I start the X Server, A diffrent set of pages are hit. Could
anyone please explain how the VGA Monitor works in QEMU? Or if someone
could suggest an alternate solution to determine amount of screen activity
while playing diffrent applications?

[NOTE : I have already checked for the region where X server pages are
mapped using cat /proc/iomem. But pages are not getting written to the
"possible" X server mmapped region.]

Regards,
-- 
Shehbaz Jaffer
Graduate Student
Department of Computer Engineering
Indian Institute of Technology, Delhi

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Re: [Qemu-devel] Monitoring Screen Activity in QEMU/KVM

[Richard W.M. Jones]

On Wed, Jun 26, 2013 at 07:47:47AM +0530, Shehbaz Jaffer wrote:
> I want to determine the amount of screen activity taking place on VGA
> monitor/ Screen for different applications (eg. playing vlc video, normal
> typing.)
> 
> When I do not start the X server, I can easily determine the screen
> activity by counting the number of pages accessed in the region 0xA0000 -
> 0xBffff (This is the VGA Monitor region in boot screen).
> 
> However when I start the X Server, A diffrent set of pages are hit. Could
> anyone please explain how the VGA Monitor works in QEMU?

qemu emulates a PCI device.  Probably an ancient Cirrus Logic CL 5446,
but other devices are possible.

> Or if someone
> could suggest an alternate solution to determine amount of screen activity
> while playing diffrent applications?

I would take an existing VNC client and modify it to log the "screeen
activity" you want to log.  VNC is a well-documented protocol, there
are several high quality open source clients [gtk-vnc is the one I'd
pick], and doing this means the guest can run at full speed.

It depends a lot on how you define "screen activity".

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://people.redhat.com/~rjones/virt-top