SIESTA introduces a virtual host which encapsulates the actual host
and instead of communicating with the real host it does its
business with the hosts virtual substitute. Since this virtual host
knows everything about jobs that are running on itself, it is able to
correct that portion of the host's load which was produced by jobs
that have been submitted by SIESTA. For each of these jobs the
virtual host adds a correction term which compensates the delay
inherent to the operating system load. Figure 6.5 shows
this procedure in detail.
los is the load which is reported by the operating system, whereas lcorr denotes the correction which is added in order to obtain the effective load leff.