Re: P9, Linux and RDP like desktop virtualization

Hi Yvan,



Il giorno lun 6 apr 2020 alle ore 17:42 Yvan Janssens <friedkiwi@xxxxxxxx>
ha scritto:

I have done a lot of remote desktop-related work, and there's a few things
to know:

The Xrdp stack indeed uses VNC as a fallback, which is rather slow. This
doesn't help.

Modern browsers use GPU acceleration to render both their UIs and web
pages. When running it on on the X11->VNC->RDP combination this also incurs
the penalty of having to do software rendering of what's essentially now
OpenGL-based cruft.

Clearly this is one of the problems since as soon as we use Firefox in a
Power Linux Virtual session we receive a warning that there are no hardware
accelerators.

The way MS (and Citrix) manged to make RDP (and ICA) fast, is done using

several means:
- instead of VNC over TCP, it uses h.264 over UDP nowadays. H.264 has
hardware acceleration in pretty much anything out there, so it's often
vastly faster than encoding JPEG chunks and shoving them down a line. It
also allows graceful degradation due to it being sent over UDP and the
stream being fault-tolerant

Even with Windows RDP we don't use TCP and force all the traffic to UDP
(otherwise often lags).

- when possible, Windows uses the H.264 capabilities of your GPU, so in
effect, you're not doing software rendering anymore. We're currently at a
point where you can play last years' AAA games over RDP.
- legacy RDP also transmitted GDI calls, and these were rendered locally.
That's why FreeRDP contains quite a complete implementation of Windows' GDI
because instead of rendering it server side and passing through the image
data, the UI API calls are passed through and the image is rendered locally.

No ideas or experiences on how to replicate this in Linux?

TL;DR, Linux runs about two decades behind in innovation on remote desktop
rendering because it never had a _real_ need for it.

Why? I find the RDP idea very useful and I don't understand why Linux had
no real need for it.

/y

Thanks for your insights

-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of
Patrik Schindler
Sent: 06 April 2020 16:34
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: P9, Linux and RDP like desktop virtualization

Hello Nathan,

Am 06.04.2020 um 16:30 schrieb Nathan Andelin <nandelin@xxxxxxxxx>:

My understanding is that Windows RDP only supports a single session,

while I suspect the Linux products support multiple.

What exactly is a "session" according do your definition? When I open up a
RDP Client and connect to a Windows Terminal Server, there may be multiple
users active at once, plus mine.

Frank Soltis has remarked on numerous occasions that *nix was

fundamentally designed as a single-user operating system.

Maybe you're referring to https://en.wikipedia.org/wiki/History_of_Unix

"At this stage [around 1970], the new operating system was a singletasking
operating system, not a multitasking one such as Multics."

Apparently, it's not clear when UNIX adopted multi-tasking and multi-user
capability. But if Frank refers to this 50 year old roots, to me it's the
same when people in here rage that IBM i on POWER is not the AS/400.

Perhaps your testing confirms that.

No. His testing confirms either that the conversion of the XServer's
remote protocol abilities to Remote Desktop Protocol sucks, or that the
Browser's Code isn't really fast in PPC, as described in a former message.
If I remember right, the RDP Server components (for Xrdp) use VNC as a
translational common protocol, and VNC *is* very slow. It's good because of
platform independence and for remote service but I can't imagine to do
serious work with it as transport protocol.

Just consider the overhead of hosting multiple Linux sessions on a

single server.

It's less overhead than using multiple servers with single users. It's
mostly the same as with Windows Terminal Services. What overhead are you
referring to?

:wq! PoC

PGP-Key: DDD3 4ABF 6413 38DE - https://www.pocnet.net/poc-key.asc


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