<div dir="ltr"><div><div><div><div><div><div><div><div><div><div>Robert <br><br></div>Thanks for all of your information on the low latency kernel. I've used x2go for several years and one use-case I've had was to install the x2go server onto either Amazon's AWS EC2 or on Digital Ocean to support remote desktops for K-12 schools that I do volunteer work for.<br><br></div>Clients have always been a mix of Win7, Mac or Ubuntu linux.<br><br></div>Really the only issue has been video streaming which for K-12 is important because alot of learning content online consists of video.<br><br></div>In the past I've tried using larger "compute" instances (8-16 core) in those clouds thinking perhaps the video encoding/transmission load was the cause but that only improved things marginally. <br><br></div>I tried higher bandwidth links... same marginal improvement.<br><br></div><div>It didn't matter what client they used (mac, win7 or linux) the video content viewing results was more or less the same for each. <br>That's why I am thinking maybe only the server-side "may" be required to have the low latency kernel?? <br></div><div><br></div><div>I got them all so the streaming video (say youtube) wasn't awful but it wasn't the same as watching the video on a dedicated PC instead of thru the x2go virtual desktop.<br></div><div><br></div>But i guess I never suspected the linux kernel introducing delay/jitter to the point of being the cause.<br><br></div>It may take a while until I can get to it but I'll try and set up a test with one of those clouds and have the x2go server-side ubuntu utilize the low latency kernel you described and see what happens with each client.<br><br></div>This would be great if that turns out to be the source of streaming video jerkiness for cloud based remote desktops. I'll post something to the x2go alias when I find out what happens.<br><br></div>thanks again.<br><br></div>Brian<br><div><div><div><div><br></div></div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Apr 1, 2015 at 5:55 PM, Robert Dinse <span dir="ltr"><<a href="mailto:nanook@eskimo.com" target="_blank">nanook@eskimo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
In Ubuntu, they build low latency kernels and make them available as<br>
part of the distribution but not installed by default.<br>
<br>
On my workstation, which is an old Mac-Pro 1,1 with quad Xeon CPU's and<br>
4 GB of RAM, I had Ubunto 14.04 installed then upgraded to 14.10. I had<br>
Wine installed and under Wine I ran WinAmp to play music. WinAmp sometimes<br>
skipped, and also when I upgraded to 14.10 which came with a 3.16.x kernel,<br>
I had issues with the Nvidia drivers for my old 7300 GT card.<br>
<br>
To solve those issues I ended up building a 3.18.9 kernel and built it<br>
with kernel preemption enabled, which is how Ubuntu builds their low latency<br>
kernels. That solved both my issues with Nvidia drivers and with WinAmp<br>
stuttering but it did not fix the issues of video being jerky over X2Go, and<br>
I had pretty much written that off to my Comcast connection anyway.<br>
<br>
But given how much smoother things went on my workstation, I decided to<br>
try installing the low latency kernel on the server and then tried watching<br>
some Youtube videos that had previously been jerky (audio okay but video<br>
jerky) and found that it made the video smooth.<br>
<br>
So my guess is you probably need it on both, but since I haven't tried<br>
it on the server only I can't say for sure.<br>
<br>
The kernel on the server isn't custom built, it's one of the low latency<br>
kernels provided by Ubuntu (I used synaptic package manager to select and<br>
install, rebooted, then removed the old).<br>
<br>
On the Mac I don't know. I had so much problems with X2Go on my Mac, even after installing the XQuartz server, that is one of the reasons I installed Ubuntu on it and stopped using MacOS. Got tired of the spinning beach ball, got tired of having zero games available. I liked the Dock but that's about it. Mac's approach of just throw enough hardware at it and it will be acceptable works if you have infinite money, I don't.<br>
<br>
With respect to Windows, I only have an old antique XP machine that I use<br>
for some games, don't really know how it would work with video over X2Go so<br>
can't answer that one.<span class=""><br>
<br>
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On Wed, 1 Apr 2015, brian mullan wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Date: Wed, 1 Apr 2015 17:36:06 -0400<br>
From: brian mullan <<a href="mailto:bmullan.mail@gmail.com" target="_blank">bmullan.mail@gmail.com</a>><br>
To: Robert Dinse <<a href="mailto:nanook@eskimo.com" target="_blank">nanook@eskimo.com</a>><br>
Cc: <a href="mailto:x2go-user@lists.x2go.org" target="_blank">x2go-user@lists.x2go.org</a><br>
Subject: Re: [X2Go-User] Jerky Video Fixed<div><div class="h5"><br>
<br>
Robert this is very interesting.. mainly because I wasn't aware there was<br>
such a thing as a low latency kernel. Guess with linux you are always<br>
learning. However, I have an experimental question. Is it just the kernel<br>
on the video transmitting side, the client/receiver side or both that the<br>
low latency kernel has this impact? Also, if the video server side is<br>
linux with a low latency kernel then what would a client running x2go on a<br>
mac or a windows 7 machine experience since neither utilize a linux kernel<br>
?<br>
Thanks for sharing as I had always figured it was a latency problem but<br>
I assumed it was 100% due to the network itself.<br>
Bria<br>
On Apr 1, 2015 5:23 PM, "Robert Dinse" <<a href="mailto:nanook@eskimo.com" target="_blank">nanook@eskimo.com</a>> wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
I hope I've done this in a way that doesn't steal anyone else's<br>
thread.<br>
<br>
A while back someone posted that they had somewhat jerky video through<br>
x2go, and I posted that if I watched someone on youtube over an x2go<br>
connection, with a 20 mbit/s cable connection, on a Ubuntu 14.10 client<br>
accessing a Ubuntu 14.04.2 LTS server, I also had some jerkiness to the<br>
video.<br>
<br>
I have installed low latency kernels on both machines now and that<br>
eliminated the jerkiness. I can now watch a youtube video on a remote<br>
machine<br>
and have it display smoothly even with the highest quality setting set.<br>
<br>
Just posting this so if others are experiencing this problem this may<br>
be<br>
a viable fix for them.<br>
<br>
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</blockquote>
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</blockquote></div><br></div>