[X2Go-User] Latency Issues

[Nirav Shah]

Thanks Steve and Mike for the guidance you have provided. I really
appreciate your help.

My servers are available in California and the developers are working in
Europe and in India. So the ping time varies from 150 ms to 400 ms. I have
selected ADSL with 16m-jpeg connection. The developers are accessing Linux
environment with GNome. They use some Java 2D graphics for the development.
Their normal bandwidth (tested using Speedtest.net) is around 3-5 MBPS.

The replies from Mike and Steve, I understood that  for this kind of high
latency I should use "WAN" connection speed with compression method - "No
Pack". Is this my understanding correct?

 I have already set Image quality to 1 and disabled audio/print/shared
folder support.

I have also used libjpeg-turbo library on the server side (Linux OS).


Will this kind of setup work? If I upgrade hardware on my server/client,
will it make any difference? Can X2go handle this kind of latency issues
with some settings? Is there any minimum bandwidth required with this
latency?


Thanks,
Nirav


On Sat, Nov 23, 2013 at 4:24 PM, Mike Gabriel <
mike.gabriel at das-netzwerkteam.de> wrote:

> Hi all,
>
> thanks Steve for your contribution. Very good.
>
>
> On  Sa 23 Nov 2013 20:11:25 CET, Steve Bergman wrote:
>
>  I am using X2Go Client and we are facing Latency issues when
>>>
>> developers use it from different country and they use graphics
>> functionalities.
>> ---
>>
>> I'm new to x2go, but have a good bit of experience administering FreeNX
>> for business desktops served over WANs. In Session Preferences ->
>> Connection, experiment with the slider settings. In particular, MODEM,
>> ISDN, and ADSL. I find that ADSL works best over my 3 - 10 mbit/s WANs. But
>> if yours are slower, MODEM or ISDN might work better. On a fast WAN, MODEM
>> and ISDN make the updates clunkier by limiting the update rate, and
>> possibly other things. It's hard to predict all interactions. But you might
>> even try 'WAN' for a relatively high bandwidth, high latency connection.
>> The higher slider levels are good for latency. But note that 'LAN' provides
>> no compression at all. It's likely to perform quite badly.
>>
>> Also, on that same page, you can reduce the image quality, which defaults
>> to 9 (highest quality) but supports a range from 0 to 9. I'm not familiar
>> enough with the "Method" options to make a recommendation. I suspect the
>> default is probably pretty good.
>>
>> To give you an idea what you should be able to expect, NX technology over
>> a 3mbit full duplex link with a ~150 - 200ms latency between sites provides
>> very usable business desktops (Mail, browsing, Libreoffice) for my ~100
>> desktop users. About 50 of those are over the WAN, and the rest are on the
>> local LAN. I know of nothing that even remotely compares to FreeNX/x2go for
>> performance over a WAN.
>>
>> Please experiment and report back. I'm interested in your results. And
>> please tell us more about your problematic workload. The ping times to the
>> clients, the nominal bandwidth, etc.
>>
>
> With connection speed X2Go (i.e. NX) is very good, even on very low speed
> lines.
>
> However, with latency issues things become different. As latency is
> defined as the amount of time the data needs to traverse from client to
> server / server to client, we should make sure that on high latency
> connections, data is as processed as fast as possible.
>
> So my basic idea about this is, that what you actually need to reduce is
> the time that is required for processing/caching/compressing images etc. On
> high latency lines it helps to have good bandwidth available, because you
> (in theory) can use the high bandwidth to compensate for high latency. E.g.
> by choosing a faster but less effective algorithm for compression (or not
> compressing images at all).
>
> My personal problem here: I cannot test this theory, because I do not have
> high latency connections here to test this with. I know that you can
> simulate high latency / low bandwidth in a lab setup, but I neither have
> time nor resources for doing that.
>
> Greets,
> Mike
>
>
>
> --
>
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>
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-- 
Thanks,

Nirav Shah
(C) (412) 296-9491
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