Beyond speed tests: Steam performance
Zen and the fine art of your Steam library maintenance. Today nosotros're taking a look at how well the UK'southward largest ISPs perform when users download games from Steam. Using our measurement client for Steam, that runs on SamKnows Whiteboxes and the Router SDK, we generated data for analysis in SamKnows Ane. Hither's what we institute.
Today we're taking a await at how well the Great britain'due south largest ISPs perform when users download games from Steam.
Anyone familiar with PC gaming will take come across Steam, the game distribution network operated past Valve. Steam was originally built-in out of the need to evangelize patches to Valve's ain games in 2002, but quickly expanded into an online store where games produced by Valve and other publishers were sold and distributed. And business is booming — as of 2017, approximately 18% of PC game sales were made using Steam, representing around $iv.3 billion in acquirement.
Steam'south ascent to becoming the leading online game distribution platform was made possible thank you to the global rollout of loftier-speed broadband services. But the games delivered via Steam have increased in size dramatically over the years, with some games now exceeding 75GB! Even on a 100Mbps broadband connection, a 75GB game would take yous around 2 hours to download (assuming yous could consistently hit full bachelor speed).
With over 150 million registered users and games measuring in tens of gigabytes, it is easy to see how Steam generates a lot of traffic. At the time of writing, Steam's peak network utilisation was 5.7Tbps (5,700Gbps) over the by calendar week. Some ISPs, such every bit MyRepublic in Australia, recognise the importance of Steam to gamers and employ average Steam download speeds in their advertising.
How Steam delivers content
As might be expected, Steam makes extensive use of CDN (Content Delivery Networks) to evangelize games to end users. In fact, Steam uses multiple different CDNssimultaneously.In our testing so far, we've establish that Steam uses Level3, Akamai, EdgeCast (Verizon), Stackpath (formally Highwinds) and their own CDN for content delivery.
Steam breaks the world upward into "cells" and maps countries and regions to these cells. For the curious among you lot, this mapping tin can be establish here, and reveals a lot about their network topology. Interestingly, customisations exist for specific ISPs like Verizon, Telus, and Shaw. These ISP-specific customisations appear to bias users on these ISPs towards specific CDN locations rather than innovate caches inside their networks (like Netflix and YouTube practise).
Each cell is allocated a listing of approximately 20 servers, which may be distributed among multiple CDNs. For example, the Uk is separate into 2 cells — London and Manchester. Both are primarily served by Valve's own CDN, with what appear to be backups using Stackpath (in Amsterdam) and Edgecast (in London).
The Steam client downloads a game in "chunks" using multiple parallel TCP sessions to a selection of the servers in the user's cell. In our testing we found that the Steam client used six parallel TCP sessions. Using multiple parallel connections to multiple CDNs is a skilful manner of working around congested paths between a user'southward Internet access provider and whatever ane specific CDN.
How we measure out Steam
We've developed a measurement client for Steam that can run on SamKnows Whiteboxes and routers running the SamKnows Router SDK. Our Steam client mimics the behaviour of the real Steam client, by logging into the Steam network, retrieving its local Cell ID, and then looking up a list of available servers and chunks for the jail cell the user resides in. We fabricated use of an offload server to centrally collate server lists and chunk lists for each cell. Once the server lists and chunk lists have been obtained, the client fetches the chunks using six parallel TCP sessions for a fixed duration of ten seconds.
Our Steam measurement client captures the post-obit data on each test run:
- The cell that served content for the user
- The average DNS lookup fourth dimension for the servers in the jail cell
- The boilerplate round-trip latency to servers in the cell
- The total download speed across all parallel TCP sessions
How we used SamKnows I to analyse the results
As always, we used SamKnows One to analyse the measurement data we collect then compare it to our existing measurements. SamKnows One is our powerful cyberspace operation measurement platform that sits in the cloud, with the capacity to analyse, visualise, and store vast quantities of data. In this instance, nosotros were interested in comparing the download speed accomplished to Steam'south CDN against the download speed achieved to our own high-chapters test servers. This kind of analysis is easy to perform in SamKnows One, as multiple independent metrics can be added to a single chart.
How Steam measures upwards in the Great britain
We carried out measurements from approximately 200 Whiteboxes distributed beyond the fastest 76Mbps FTTC (VDSL) from BT, Heaven, TalkTalk, and Vodafone, and 200Mbps and 350Mps cable products from Virgin Media. Measurements were carried out over a four-day menses in August 2018.
All of the major United kingdom ISPs performed similarly when downloading from Steam. The Steam measurements for all ISPs recorded 50–70% of the speed of the regular download speed test. This suggests that the Steam CDN can struggle to saturate the link completely at higher speeds. Of form, in terms of absolute speeds, Virgin unsurprisingly rules the roost with their 200Mbps and 350Mbps products (50% of 350Mbps is a lot faster than l% of 76Mbps!).
Figure 1 below shows the boilerplate download speed over Steam versus the average download speed to our dedicated servers.
Figure 1: SamKnows 1
Similarly, there is no indication of whatsoever routing anomalies to the Steam CDNs, with all ISPs seeing circular-trip latency in the low double digits. This can exist seen in Effigy two beneath, with a comparison to our latency measurement to our dedicated test servers.
Figure 2: SamKnows One
Measurements were distributed evenly betwixt the London and Manchester Steam "cells", and in that location was no discernible difference in performance between the two.
Determination
The sheer size of modernistic games means that the download speed that can be achieved for Steam will be something that gamers care a lot nigh. ISPs are already recognising this, and some have started to advertise on the back of high-level data that Valve publishes most performance to Steam.
Like other services nosotros've looked at lately, Steam makes extensive utilise of CDNs to deliver content. Steam takes a subtly different approach to that of the video stream providers though — it downloads data from multiple different CDNs simultaneously. This will have little practical affect in a market like the United kingdom of great britain and northern ireland, where peering between ISPs and content providers is generally open up and very skilful. However, in other markets with less open peering arrangements (all the same common in South Due east Asia and S America), downloading from multiple unlike CDNs simultaneously may assistance offset poor operation to any one of them.
Here at SamKnows nosotros will continue developing measurements that go beyond simple speed tests and measure the performance of real applications. It'south only by measuring the performance of real applications that nosotros can accurately characterise user experience. Keep your optics peeled for the next instalment in this series!
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