The safety parameter in percentage (at scale from 0 to 1). It is a tuning parameter used by the allocation policy to estimate host utilization (load). The host overload detection is based on this estimation. This parameter is used to tune the estimation to up or down. If the parameter is set as 1.2, for instance, the estimated host utilization is increased in 20%, giving the host a safety margin of 20% to grow its usage in order to try avoiding SLA violations. As this parameter decreases, more aggressive will be the consolidation (packing) of VMs inside a host, what may lead to optimization of resource usage, but rising of SLA violations. Thus, the parameter has to be set in order to balance such factors.

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https://github.com/Cloudslab/cloudsim/blob/master/modules/cloudsim/src/main/java/org/cloudbus/cloudsim/power/PowerVmAllocationPolicyMigrationInterQuartileRange.java