<div dir="ltr"><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div>Robert I thought I'd get back to you on the low latency kernel discussion.<br><br></div>Over the weekend I created 2 "cloud" servers. One on AWS EC2 and one on Digital Ocean. On both of them I install x2goserver<br></div>and the Ubuntu low-latency kernel.<br><br></div>At home I used a spare esata drive and installed the final beta of Ubuntu 15.04 onto it with the low latency kernel also.<br><br></div>My first test was with the x2go client on my normal home Ubuntu 14.04 machine.<br><br></div><div>All tests used:<br></div><div>ubuntu 15.04 final beta on server side with low latency kernel installed (uname -r showed it as the active kernel)<br></div><div>firefox v37 release<br></div>same youtube video (I used Santana's "Smooth" video)<br></div><div>x2goclient "connection" speed set to LAN (I also tried WAN with little observable difference)<br></div><div>my home desktop is 8 core, 32GB ram, 6TB sata-6 sw RAID<br></div><div>my home desktop internet connection is 20Meg <br></div><div><br>Test 1<br>use x2goclient to log into AWS EC2 "cloud" x2goserver <br></div>start firefox<br></div>goto youtube and watch a video<br></div>client side did NOT have the low latency kernel<br><br></div><div>Result of test 1<br></div>video still somewhat choppy<br><br>Test 2<br>use x2goclient to log into Digital Ocean ubuntu x2goserver <br>start firefox<br>goto youtube and watch a video<br>client side did NOT have the low latency kernel<br><br><div>Result of test 2<br></div>video still somewhat choppy<br><br>Test 3<br>use x2goclient to log into AWS EC2 "cloud" x2goserver <br>start firefox<br>goto youtube and watch a video<br>client side DID have the low latency kernel<br><br><div>Result of test 3<br></div>video still somewhat choppy<br><br>Test 4<br>use x2goclient to log into Digital Ocean ubuntu x2goserver <br>start firefox<br>goto youtube and watch a video<br>client side DID have the low latency kernel<br><br><div>Result of test 4<br></div>video still somewhat choppy<br><br>Test 5<br>Booted Windows 7 on my home machine, installed x2goclient and firefox v37<br>use x2goclient to log into AWS EC2 "cloud" x2goserver <br>start firefox<br>goto youtube and watch a video<br>client side being Windows obviously did NOT have the low latency kernel<br><br><div>Result of test 5<br></div>video still somewhat choppy<br><br></div>Test 6<br></div>Repeated Test 5 (windows 7) but used DIgital Ocean ubuntu server again w/low latency kernel installed<br><br></div>Result of test 6<br></div>video still somewhat choppy<br><br></div>Test 7<br></div>Tried all of the above but using Youtube HTML5 video instead of Flash based video<br><br></div>Result of test 7<br></div>same as before ... somewhat choppy<br><br></div>My own results <u>were not able to replicate</u> your success with low latency kernel using this "remote" desktop x2go testing to cloud based x2goservers.<br></div>So I suspect that the difference may be the WAN and/or cloud introduced latencies but that would take alot more work and probably some wireshark sniffing of packets to know for sure.<br><br></div>Finally, I remembered one "good practice" I had always been using and that was to install libjpeg-turbo on all my server's and my home PC clients (except the Win7 of course).<br><br></div>Reference: <a href="http://libjpeg-turbo.virtualgl.org/">http://libjpeg-turbo.virtualgl.org/</a><br><div><div><div><div><br><div><div><div><div>The reason as you see when reading the above website is that libjpeg-turbo is 2-4 times faster coding/decoding jpeg than the default libjpeg in most linux distro's.<br><br></div><div>Retested here does show "some" improvement in video but still not as good as directly watching that same youtube using Firefox on my local desktop.<br><br></div><div>note: another benefit of using libjpeg-turbo is that besides being 2-4 times faster than default libjpeg it also uses less-cpu which for the server-side can be helpful when multiple x2go sessions are active or<br></div><div> more than one x2go user is logged into that server<br><br></div><div>Anyway, I had hoped for a different outcome but unless I can think of something else I may/may not have done this approach didn't help much in my use-case of remote desktop to cloud serves.<br><br></div><div>Of course using x2go everything but streaming video from those cloud servers worked great.<br><br></div><div>If you can think of anything else let me know and I'd be glad to try to see if I can get diff results for the streaming video.<br><br></div><div>Brian<br><br></div><div><br><br><div><div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Apr 2, 2015 at 12:17 PM, brian mullan <span dir="ltr"><<a href="mailto:bmullan.mail@gmail.com" target="_blank">bmullan.mail@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><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.<span class=""><font color="#888888"><br><br></font></span></div><span class=""><font color="#888888">Brian<br><div><div><div><div><br></div></div></div></div></font></span></div><div class=""><div class="h5"><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:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);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><br>
<br>
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On Wed, 1 Apr 2015, brian mullan wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);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><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:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);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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