Slashdot Mirror
OnLive Latency Tested
The Digital Foundry blog has done an analysis of recently launched cloud gaming service OnLive, measuring latency across several different games. Quoting:
"In a best-case scenario, we counted 10 frames delay between button and response on-screen, giving a 150ms latency once the display's contribution to the measurement was removed. Unreal Tournament III worked pretty well in sustaining that response during gameplay. However, other tests were not so consistent, with DiRT 2 weighing in at 167ms-200ms while Assassin's Creed II operated at a wide range of between 150ms-216ms. ... OnLive says that the system works within 1000 miles of its datacenters on any broadband connection and recommends 5mbps or better. We gave OnLive the best possible ISP service we could find: Verizon FiOS, offering a direct fiber optic connection to the home. Latency was also reduced still further simply due to the masses of bandwidth FiOS offers compared to bog standard ADSL: in our case, 25mbps."
The statement is silly because latency isn't directly related to bandwidth. Switches, bridges, repeaters, modems, routers and other such devices all add latency. If FiOS reduces the number of these in the chain, the latency will be reduced. I'm not saying it necessarily does - just that it could provide better latency without having more bandwidth because of other factors.
Yep, you're absolutely right in that bandwidth and latency aren't the same. However, when used by TCP in latency sensitive environments, common asymmetric connections can quickly saturate their available upstream bandwidth. This means that they're not able to ACK incoming packets, effectively increasing their link latency and reducing its throughput. So, in reality, total throughput is a combination of link latency and the ability to quickly respond to the protocol stream to keep the bits flowing. This is why QoS for TCP is so important on heavily utilised asymmetric connections.
In the UK there aren't many options at all. Eurogamer.net is UK-based, hence the mention of BT.
My company don't want the expense of using leased line and other specialist stuff, just an ordinary thing that can work like a home package over an ordinary phone line. The FASTEST damn thing we can have is a single or multiple ADSL2 lines. We have basically unlimited funds for such things and often specify overkill-measures (i.e. 3 or 4 ADSL2 lines from seperate suppliers rather than 1 leased line). We get 20Mbps sync and a little less real-world speed. We are approximately 10 metres from the exchange. We are in an affluent and well-populated area of London.
In terms of what the average home user can have, only Virgin media fibre really beats the other offerings but that's highly variable and although you are told "up to 50MBps", the infrastructure isn't there to give you that as usable bandwidth.
To be honest, I'm impressed they managed to get what they did considering the state of UK broadband. Of course, you can pay stupid money and get serious pipes put in but that's hardly a "real world" scenario for the average home user. It's not unimaginable, though, that a true gamer might have the best a home user can be offered - which in the UK is a 25/50Mbps fibre service.
Remember they don't just send the inputs there. They have to get the display back again.
If each frame is 100Kilobytes and they need 30fps to look smooth that's approaching the limit of 25Megabits/s (=3.125Megabytes/s).
Damn it, kids, Latency and bandwidth are not the same thing and anybody who makes that mistake should be forced to use a "1Gb/s" connection via fedex.
A highly saturated connection will, in practice, have higher latency. Therefore, bandwidth and latency are related. HTH, HAND.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"