[Spice-devel] Questions regarding Bug 62033 - Means to detect local-only

[Fedor Lyakhov]

Hi David,

Thanks for your answer. Please see my comments below.


On Mon, Jun 24, 2013 at 3:47 PM, David Jaša <djasa at redhat.com> wrote:

> Hi Fedor,
>
> I'd personally prefer to:
> 1) monitor bandwidth and latency continuously - there's a long-standing
> RFE for it and IIRC Yonit has posted some proof-of-concept patches in
> recent months (as a part of her streamlining of video streams)
> 2) set the options on-the fly as the conditions allow to get at the right
> position in b/w-saving <---> cpu saving scale
>
> The reason for this preference of mine is two-fold:
> * idle gigabit or 100Mbps LAN may be closer to localhost behaviour than
> WAN behaviour, especially with decreasing stream resolution
> * such behaviour would be consistent with the rest of the spice protocol
>

[FL] I agree with your points. So implementation will be based on
continuous bandwidth and latency monitoring and reporting. This means we'd
need a heuristic algorithm to detect a threshold for 'bad' and 'good'
connection (and reporting the threshold has been crossed in one or another
direction).



>
> I'm also not sure if I follow what you want to do with an agent:
> 1) the agent runs in the guest OS and communicates already with the client
> through using spice means - i.e. agent - virtio-serial/qemu - spice-server
> - spice client. You shouldn't need to invent any other client <--> agent
> connection, and I can't get how such thing should help you...
> 2) agent has no connection of what happens with display, and it has a
> limited knowledge of network conditions as it handles just a subset of all
> the traffic. spice-server and spice client actually do have complete
> picture of what happens on the wire
>
>
[FL] I do understand all this. Sorry for my previous bloated e-mail giving
you wrong picture of what I'm suggesting.
New functionality for vdagent is required: an interface for applications
running at guest OS. In particular, gnome-settings-daemon needs to know
whether the connection is good or bad, and toggle animations accordingly. I
see following options for interface vdagent<->guest-apps:
1. D-Bus (low-level API, or GLib bindings)
2. Raw socket with custom protocol (similar to vdagent <-> vdagentd)

Personally I'd prefer D-Bus, since looks like this is the best interface
for freedesktop-based environments.

This is interface facing users (apps at guest); for internals I'm going to
reuse current vdagent<->vdagentd communication mechanism, and vdagentd
-virtio-serial/qemu - spice-server (which will provide the actual state,
'good' or 'bad', and report the metrics probably).

If D-Bus is approved, I can think of enhancing vdagent<->vdagentd
communication from socket to D-Bus as well.


-Fedor
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