Control device, disk drive, control method, and storage medium

A disk drive comprising:

• a disk;
• a head that is able to read data stored in the disk and to write data to the disk;
• and
• a control device including a processor,
• wherein the control device is configured to perform a first determination process,
• wherein the processor is configured to perform a first calculation process which is performed to control a position of a head of the disk drive, a second calculation process which is able to be performed at the same time as the first calculation process, and an alternative process which is performed to hold the position of the head at a predetermined position with a calculation load smaller than that of the first calculation process,
• wherein the first determination process is a process which is performed on the basis of information stored in a predetermined storage medium when it is determined that the second calculation process is to be performed,
• wherein the information stored in the storage medium includes a first processing time which is required until the second calculation process is completed when the processor performs only the second calculation process, a second processing time which is required until the position of the head is held at the predetermined position through the alternative process instead of the first calculation process, a third processing time which is required to restart the first calculation process which has been stopped by performing the alternative process, a first process occupancy ratio of the processor which is required to perform the first calculation process, and a second process occupancy ratio of the processor which is required to hold the position of the head through the alternative process,
• wherein the first determination process includes:
• acquiring a first execution time expressed by TA/(1−k1) and a second execution time expressed by {TA/(1−k2)}+TB+TC on the basis of the information stored in the storage medium where the first processing time is defined as TA, the second processing time is defined as TB, the third processing time is defined as TC, the first process occupancy ratio is defined as k1, and the second process occupancy ratio is defined as k2;
• and
• selecting a second execution method different from a first execution method of performing the second calculation process while performing the first calculation process as a method of performing the second calculation process when the second execution time is less than the first execution time, and
• wherein the second execution method is a method of starting the alternative process instead of the first calculation process and then performing the second calculation process.

A control method for a disk drive, the control method comprising:

• a first calculation process which is performed to control a position of a head of the disk drive;
• a second calculation process which is able to be performed at the same time as the first calculation process;
• an alternative process which is performed to hold the position of the head at a predetermined position with a calculation load smaller than that of the first calculation process;
• and
• a first determination process which is performed on the basis of information stored in a predetermined storage medium when it is determined that the second calculation process is to be performed,
• wherein the information stored in the storage medium includes a first processing time which is required until the second calculation process is completed when the processor which is able to perform the first calculation process, the second calculation process, and the alternative process performs only the second calculation process, a second processing time which is required to perform the alternative process instead of the first calculation process, a third processing time which is required to restart the first calculation process which has been stopped by performing the alternative process, a first process occupancy ratio of the processor which is required to perform the first calculation process, and a second process occupancy ratio of the processor which is required to hold the position of the head through the alternative process,
• wherein the first determination process includes:
• acquiring a first execution time expressed by TA/(1−k1) and a second execution time expressed by {TA/(1−k2)}+TB+TC on the basis of the information stored in the storage medium where the first processing time is defined as TA, the second processing time is defined as TB, the third processing time is defined as TC, the first process occupancy ratio is defined as k1, and the second process occupancy ratio is defined as k2;
• and
• selecting a second execution method different from a first execution method of performing the second calculation process while performing the first calculation process as a method of performing the second calculation process when the second execution time is less than the first execution time, and
• wherein the second execution method is a method of starting the alternative process instead of the first calculation process and then performing the second calculation process.