CDN – Lab issues data on improvements

On top of their feature blog post on recent improvements to SL, on which I also blogged, the Lab has also issued a Tools and Technology update with data on the initial deployment of the CDN.

Entitled CDN Unleashed, the post specifically examines the percentage of simulator servers experiencing high load conditions (and therefore potentially a drop in performance) on the (presumably) BlueSteel RC both before and after deployment of the CDN service to that channel – and the difference even caught the Lab off-guard.

Charting servers on a production release candidate channel with high HTTP load conditions before and after we rolled the CDN code onto them (image via Linden Lab)

While a drop in load had been expected prior to the deployment, no-one at the Lab had apparently expected it to be so dramatic that it almost vanishes. Such were the figures that, as the blog post notes, at first those looking at them thought there was something wrong, spending two days investigating and checking and trying to figure out where the error in data came from – only it wasn’t an error; the loads really have been dramatically reduced.

Elsewhere, the blog post notes:

Second Life was originally designed for nearly all data and Viewer interactions to go through the Simulator server. That is, the Viewer would talk almost exclusively to the specific server hosting the region the Resident was in. This architecture had the advantage of giving a single point of control for any session. It also had the disadvantage of making it difficult to address region resource problems or otherwise scale out busy areas.

Over the years we’ve implemented techniques to get around these problems, but one pain point proved difficult to fix: asset delivery, specifically textures and meshes. Recently we implemented the ability to move texture and mesh traffic off the simulator server onto a Content Delivery Network (CDN), dramatically improving download times for Residents while significantly reducing the load on busy servers.

Download times for textures and meshes have been reduced by more than 50% on average, but outside of North America those the improvements are even more dramatic.

Quite how dramatic for those outside North America isn’t clear, quite possibly because the Lab is still gathering data and monitoring things. However, the post does go on to note that in combination with the HTTP pipelining updates now available in the current release viewer (version at the time of writing), the CDN deployment is leading to as much as an 80% reduction in download times for mesh and texture data. Hence why the Lab is keen to see TPVs adopt the HTTP code as soon as their release cycles permit, so that their users can enjoy the additional boost providing the code on top of enjoying the benefits offered by the CDN.

Again, at the time of writing, the following TPVs already have the HTTP pipelining code updates:

As per the Performance, Performance, Performance blog post, the Lab want to hear back from users on the improvements. Comments can be left on the Performance Improvements forum thread, where Ebbe and Oz has been responding to questions and misconceptions, and Whirly Fizzle has been providing valuable additional information.

7 thoughts on “CDN – Lab issues data on improvements

  1. WOOT, WOOT, CDN \o/
    things are so much smoother loading now! even textures that denied in past to load fully are doing now 🙂
    LL did a real smart infrastructural move in my view.
    HTTP-pipelining will be fitting wonderful in this. As soon as TVPs get their hands on and could manage to adopt this, we will have the smoothest SL-experience since EVER!
    All this might sit under the hood, but is imho as important as the shiny things were.
    *smiling logging in*


  2. I am a little wary of what might happen when the HTTP data from the CDN Server meets up with the UDP data from the Sim Server on the last stages of the journey to my computer. I can remember dreadful warnings being given on how the TCP could mess up the UDP with retries if both were being used at the same time, and how, if you were streaming video, you got better results if you were not doing an un-restricted download.

    I think it might be time to do some rethinking of the guidelines for the bandwidth setting in viewer preferences. It only sets the UDP bandwidth from the Sim Server, and now so much data is coming from elsewhere on the net.


    1. Well, rethinking historical settings might be a good advice for any situation from year to year. But atm i think this is a real good step forward. Not only for SL but for LL it self. Not wanting sounding pathetic, but It shows in my view that the company itself is able to evolve (and not only their product). This is a good sign.
      Sure You might be total right with that compete ways to grab the assets. But that is something i expect the testing would have shown.
      Sooo, overall i think this CDN is maybe the most important step LL did in the past years with SL. We will see a increasing felt performance with the CDN filling its Servers over time, and sure some strangeness here&there.
      But for now i would say its faster and more smooth ever.


  3. This is all very good news for all of us I am sure, but you can be certain some Linden is recalculating how many regions they can cram onto each simulator now that overload is so much less likely. That is not inherently a bad thing but if they overdo it the stress will show up in some other way.


  4. I do fear like Shug that sooner all cdn improvements will be compromised as LL will reduce costs.
    But well, i cant complain to much, did a few trips on blake sea, a few races and cruises during the weekend that made me cross more then 200 sims and i didn’t crash (unfortunately the same cant be said from my soul mate, that has the same exact spec and settings but lives in Usa east coast, she did crash a lot without any explanation).
    Stil as im not ll biased, i know that sadly shug has a point and i fear that we will see cdn improvements compromised soon enough.


    1. please do not fear.
      All is bright and save.
      Due LL might feel the competitors (like FaceBook) follow in LLs field of business, we might have a moment of peaceful being.


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