When a user signs into the CloudMoV system via the login
gateway shown in Fig. 3 and gets identified, the gateway will request a virtual machine instance from the IaaS cloud to be the user’s surrogate.
The sign-in process finishes when the surrogate is initialized and the user is connected to the surrogate.
In this experiment, five mobile users repeatedly join the system
and log off as soon as the respective surrogate is initialized.
We inject JavaScript snippets into the client of CloudMov on the mobile device to record the timestamps during the sign-in process.
Fig. 9 shows the average sign-in latencies experienced
by these clients during a 4.5-hour span.
The “Front-end” latency consists of both the sign-in request/response and identification delays, while the “Back-end” latency is the surrogate VM provisioning
delay from the IaaS cloud (Amazon EC2).
We can see that most of the latencies are caused by the latter.
The delay can be significantly reduced if a VMpool ismaintained wherein idle
surrogates are initialized before hand (based on estimated user
numbers), ready for immediate allocation when new users sign
in.