[winswitch] xpra session to other account on localhost

Antoine Martin antoine at nagafix.co.uk
Sun Dec 16 05:26:40 GMT 2018

>> The defaults should include /run/xpra which should be writable by
>> members of the xpra group.
>>> --speaker=off --encoding=png/P
>> Don't change the encoding unless you really know what you are doing.
>> Especially not for png/P which is very rarely a good option.
> Removed. 
If making mmap work is not an option, you can try:
--encodings=rgb --speed=100

> That made things a bit better, but still miles apart from
> native X, especially when scrolling. Is Firefox an especially badly
> behaving application?
Browsers in general are difficult to handle.
Scrolling is also more challenging than most people imagine.

>>> 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.
>> I think you need to make the 'xpra' group the primary group of the user.
> I am tempted to say that this is an unreasonable suggestion.
> Traditionally, the primary groups of users have always been the local
> admin's domain; they're frequently used to control access of other users
> to one user's home directory. Having arbitrary software demand that the
> user's primary group is set to a software-specific group is not only an
> intrusion into that domain it also doesn't scale beyond one single piece
> of software making that demand.
> Do you need a bug report for this?
If you feel strongly about this, you can:
* subscribe to that ticket and help in testing the changes
* submit patches or add to the ticket
>>> I'd rather refrain from having to patch my xorg,
>> You're not patching xorg, just the dummy driver.
> If you mean /usr/lib/xorg/modules/drivers/dummy_drv.so, that one is, on
> Debian, from the package xserver-xorg-video-dummy. I could patch that,
> but I'd prefer to look for a cleaner solution first.
Using Xvfb instead of Xdummy may work for you, it just doesn't support
runtime DPI adjustements.

>>> 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).
>> OK.
>> Note that there is at least one more non-DPI bug you may encounter with
>> the unpatched driver.
> For example? Will the patch be part of a future xorg release?
But even if I worked on merging this upstream, distributions very rarely
apply those patches to their current branch.
So the fix would take years to land on user's systems.


>>>> (..)> 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?
>> That's a good start, more guidelines can be found here:
>> https://xpra.org/trac/wiki/ReportingBugs
>> Based on recent similar reports, you may want to attach the server's
>> debug log with "-d bandwidth,stats" added to the command line.
> Will do in due time.
> Greetings
> Marc

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