Central processing unit, method for controlling central processing unit, and information processing apparatus

A method of controlling a central processing unit connected to a main memory for storing data and a plurality of central processing units, the method comprising:

• holding a data block being part of data in a cache memory included in the own unit;
• classifying the plurality of central processing units into a first predetermined number that is set based on a total number of the plurality of central processing units upon activation of the central processing unit;
• writing presence information to the main memory indicating a presence or absence of a central processing unit holding the same data block as part of data stored in the main memory in a cache memory included in any of the central processing units that belong to a corresponding central processing unit group, for each central processing unit group of a plurality of central processing unit groups obtained at the classifying;
• and
• changing a unit number information indicating a number of the central processing unit for management of the presence information from the first predetermined number of central processing units to a second predetermined number of central processing units among the plurality of central processing units.

An information processing apparatus comprising a main memory for storing data, a central processing unit connected to the main memory, and a plurality of central processing units connected to the central processing unit, the central processing unit comprising:

• a cache memory that holds a data block being a part of data;
• and
• a control unit, wherein the control unit executes a process comprising:
• classifying the plurality of central processing units into a first predetermined number that is set based on a total number of the plurality of central processing units upon activation of the information processing apparatus;
• writing presence information to the main memory indicating a presence or absence of a central processing unit holding the same data block as part of data stored in the main memory in a cache memory included in any of the central processing units that belong to a corresponding central processing unit group, for each central processing unit group of a plurality of central processing unit groups obtained at the classifying;
• and
• changing a unit number information indicating a number of the central processing unit for management of the presence information from the first predetermined number of central processing units to a second predetermined number of central processing units among the plurality of central processing units.