an execution circuit having a plurality of operation modes, each having a different effect on processing performance and power consumption of said processing apparatus;

a measurer that measures a process execution performance of said processing apparatus; and

a controller that compares a target value with a measurement result from said measurer, and that switches the plurality of operation modes in accordance with a result of the comparison,

wherein said execution circuit includes:

a plurality of instruction execution pipelines, each of the plurality of instruction execution pipelines executing an instruction; and

an instruction issuer that simultaneously issues a plurality of instructions to said plurality of instruction execution pipelines,

wherein said measurer measures the process execution performance, based on a number of instructions processed by said plurality of instruction execution pipelines per predetermined period of time,

wherein said instruction issuer operates in said plurality of operation modes, each having a different maximum allowable number for said number of instructions that are allowed to be simultaneously issued to said plurality of instruction execution pipelines,

wherein said measurer measures said number of instructions as the process execution performance of said processing apparatus, and

wherein said controller switches a current operation mode of said instruction issuer to an operation mode having a lower maximum allowable number when the process execution performance measured by said measurer exceeds the target value, and switches to an operation mode having a higher maximum allowable number when the process execution performance measured by said measurer is below the target value.