Dynamic load balancing parameters

There are in general two basic factors causing load imbalance between individual subdomains: (i) one comming from application nature, such as switching from linear to nonlinear response in certain regions or local adaptive refinment, and (ii) external factors, caused by resourse realocation, typical for nondedicated cluster environments, where indivudual processors are shared by different applications and users, leading to time variation in allocated processing power. The load balance recovery is achieved by repartitioning of the problem domain and transferring the work (represented typically by finite elements) from one subdomain to another. This section describes the structure and syntax of parameters related to dynamic load balancing. The corresponding part of analysis record has the following general syntax:

	[lbflag$^M$ #(in)]
	[forcelb1 #(in)]
	[wtp #(ia)]
	[lbstep #(in)]
	[relwct #(rn)]
	[abswct #(rn)]
	[minwct #(rn)]

where the parameters have following meaning:

• lbflag, when set to nonzero value activates the dynamic load balancing. Default value is zero.
• forcelb1 forces the load rebalancing after the first solution step, when set to nonzero value.
• wtp allows to activate optional load balancing plugins. At present, the only supported value is 1, that activates nonlocal plugin, necessary for nonlocal averaging to work properly when dynamic load balancing is active.
• lbstep rebalancing, if needed, is performed only every lbstep solution step. Default value is 1 (recover balance after every step, if necessary).
• relwcr sets relative wall-clock imbalance treshold. When achieved relative imbalance between wall clock solution time of individual processors is greater than provided treshold, the rebalancing procedure will be activated.
• abswct sets absolute wall-clock imbalance treshold. When achieved absolute imbalance between wall clock solution time of individual processors is greater than provided treshold, the rebalancing procedure will be activated.
• minwct minimum absolute imbalance to perform relative imbalance check using relwcr parameter, otherwise only absolute check is done. Default value is 0.

At present, the load balancing support requires ParMETIS module to be configured and compiled.