[winswitch] xpra session to other account on localhost

[Marc Haber]

Hi Antoine,

On Mon, Dec 10, 2018 at 08:25:55PM -0800, Antoine Martin via shifter-users wrote:
> On 08/12/2018 11:39, Marc Haber via shifter-users wrote:
> > I would like to do an xpra connection to an xpra server running under a
> > different account on the same host. I am running Debian unstable and
> > have xpra 2.4.2. The box is a strong Six-Core machine with plenty of
> > free RAM and a fast SSD.
> > 
> > Running a Firefox browser over this connection is quite slow. I have to
> > wait multiple hundreds of milliseconds before the reaction to a click
> > can be seen. Scrolling a window takes like ten seconds until the picture
> > is completely re-drawn at full resolution. Is that the expected behavior
> > on a local host with no network involved, plenty of CPU and plenty of
> > RAM?
> No. It should be almost indistinguishable from native for all but the
> most extreme use cases.

My installation is wide apart from that.

> The most important thing for local connections is to enable mmap. (see
> mmap command line options and use "-d mmap" to enable debug logging)

My system explicitly says mmap disabled, shouldn't that be detected
automatically?

Both accounts are member of the xpra group. I start the server with
ssh marc at localhost xpra start --mmap=/var/tmp/mh-mmap -d mmap
--mmap-group --socket-dir=/var/tmp --speaker=off --encoding=png/P
--daemon=no --dpi=96 --webcam=no --mdns=no --pulseaudio=no
--start=konsole :100
which makes the socket show up in /var/tmp with marc:xpra 660. When I
then start the client as
xpra attach ssh:marc at localhost:100 --mmap=/var/tmp/mh-mmap
--socket-dir=/var/tmp --mmap-group --dpi=96 --desktop-scaling=off -d
mmap
I see /var/tmp/mh-mmap appear for a short time as mh:mh 775, then I see
the server complaining:
2018-12-11 18:36:48,410 client supplied mmap_file=/var/tmp/mh-mmap
2018-12-11 18:36:48,410 mmap supported=True, token=242228041280381797676313904508936308232
2018-12-11 18:36:48,410 using global server specified mmap file path: '/var/tmp/mh-mmap'
2018-12-11 18:36:48,411 Error: cannot access mmap file '/var/tmp/mh-mmap':
2018-12-11 18:36:48,411   [Errno 13] Permission denied: '/var/tmp/mh-mmap'
2018-12-11 18:36:48,411  see mmap-group option?
2018-12-11 18:36:48,411 found client mmap area: None, 0 bytes - min mmap size=67108864
and then the mmap file disappears again.

What am I doing wrong?

> > I notice that the server complains twice on startup:
> > 2018-12-08 20:19:08,741 cannot use uinput for virtual devices:
> > 2018-12-08 20:19:08,741  [Errno 13] Failed to open the uinput device: Permission denied
> Harmless and completely safe to ignore.
> > WARNING: no 'numpy' module, HyBi protocol will be slower
> This one is bogus.
> 
> Both have been added to the FAQ:
> https://xpra.org/trac/wiki/FAQ

Did I miss that or was it added just recently?

> > Here is what the server logs:
> > marc at fan:~$ xpra start --daemon=no --speaker=off --webcam=no --mdns=no --pulseaudio=no --start=konsole :100
> > 2018-12-08 20:20:27,121 cannot use uinput for virtual devices:
> > 2018-12-08 20:20:27,121  [Errno 13] Failed to open the uinput device: Permission denied
> (..)> 2018-12-08 20:23:57,360 DPI set to 51 x 48 (wanted 54 x 77)
> > 2018-12-08 20:23:57,361  you may experience scaling problems, such as huge or small fonts, etc
> > 2018-12-08 20:23:57,361  to fix this issue, try the dpi switch, or use a patched Xorg dummy driver
> That's odd. Make sure to use the patched dummy driver from the repository.

I'd rather refrain from having to patch my xorg, I can live with giving
hard-coded dpi values (which I usually do, but didn't do when creating
these mails to make things simpler).

> (..)> In the panel applet, I have set Picture => Fixed speed to "Lowest
> > latency". The session information claims that I have 60 ms frame total
> > latency, but it feels like a multiple of that. Any networked RDP session
> > to a Windows machine feels much faster.
> Even remote connections should be as fast as RDP, let alone local ones.

They're not.

> Feel free to create a ticket to fix the non-mmap case.

Like "xrdp very slow" and giving the same information like in the thread
starting message?

Greetings
Marc

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