[X2Go-Dev] libjpeg-turbo and NX/X2Go

[Mike Gabriel]

Hi Stefan,

On Mo 30 Jan 2012 18:37:40 CET "newsgroups.mail2 at stefanbaur.de" wrote:

> Am 29.01.2012 00:46, schrieb Mike Gabriel:
>> From my point of view it is indeed not necessary to recompile NX to  
>> be used with libjpeg-turbo. People may correct me if that is not  
>> true.
>>
>> So for a running X2Go server and client you can drop in
>>
>>   on squeeze: apt-get install libjpeg-turbo62
>>   on wheezy, sid: apt-get install libjpeg-turbo8
>>
>> And your host should then run with libjpeg-turbo instead of  
>> libjpeg. Please note, that this change affects every application on  
>> that system. So... no warranty given from our side. Also, if  
>> testing libjpeg-turbo, please read the documentation of  
>> libjpeg-turbo:
>
> Guys,
>
> it would be really helpful if someone could type up a step-by-step  
> guide for testing.

1. Install X2Go Server and Client
2. install libjpeg-turbo62 (squeeze) or libjpeg-turbo8 (wheezy + sid)  
from the heuler repos on packages.x2go.org on server and/or client
3. test the experience...

> I'd love to try this out, but either I *did* something wrong or  
> something *goes* wrong, as the following had no positive effect  
> whatsoever:
> * add heuler repository, apt-get update
> * apt-get install libjpeg-turbo62 on my squeeze-based server
> * connect from latest Microsoft Windows client to said server
> * use Iceweasel in rootless mode, access YouTube and watch a movie

What compression do you use? 16m-jpeg-9?

> The only effect I saw was a "screen hang" when leaving YouTube for  
> another web site, and no speed increase whatsoever. :-(

hmmm...

> 1) Will this currently only work between Linux Clients and Linux Servers?

jpeg compression is performed on both sides: client _and_ server, I  
guess. It can have an effect on both sides (I guess).

> 2) Will it work with rootless sessions? (I remember NoMachine/FreeNX  
> once stated that rootless sessions in general - i.e. not related to  
> libjpeg-turbo - gain less speed than a fullscreen session - but that  
> was years ago and may have changed and may not apply to X2Go at all,  
> I don't know.)

It should...

> 3) Is the library required on both the server *and* on the client?

Best performance is achieved if it is installed on both: server and  
client. But it can be installed on either, only.

> 4) Should it work "out of the box" after installing the package, or  
> do I have to change some file somewhere to add the library path?

out-of-the-box, by theory... However, we should compare a drop-in of  
the package into an already running server with an NX (redistributed)  
compiled on a system where libjpeg-turbo is installed during package  
build. Not sure if that changes performance gain...

> 5) Do I have to restart a daemon after changing this file?

No daemons involved here, at all.

> 6) Why was I able to install the package without apt-get telling me  
> it would remove the "non-turbo" library package? To make this clear,  
> I don't complain about a lack of a warning (Mike did provide such a  
> warning in his posting), but I'm surprised about the lack of  
> *action* i.e. no library package has been removed when I installed  
> the libjpeg-turbo62 package.

Please read more about dpkg-divert:
http://www.debian-administration.org/articles/118

And refer to the postrm and preinst scripts of libjpeg-turbo:
http://code.x2go.org/gitweb?p=libjpeg-turbo.git;a=tree;f=debian

> Kind Regards,
> Stefan

Greets,
Mike

-- 

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