1. Technical Field
This invention relates to managing power consumption of hardware memory devices. More specifically, the invention relates to controlling availability of hardware memory devices based upon usage and associated power consumption thereof.
2. Description of the Prior Art
Main memory is defined as an internal storage area in a computer. The term main memory identifies data storage that comes in the form of a chip. It is identified with physical memory, which refers to actual hardware in the form of microchips capable of holding data. The term storage memory identifies memory that exists on tapes or disks. Every computer is configured with a certain amount of physical memory. There are several different types of memory, including RAM, ROM, PROM, EPROM, and EEPROM. RAM is an acronym for random access memory and it is the same as main memory. When used by itself, the term RAM refers to read and write memory, indicating that a programmer can both write data into RAM and read data from RAM. Most RAM is volatile in that it requires a steady flow of electricity to maintain its contents. As soon as power is turned off, whatever data stored in RAM is lost. ROM is an acronym for read only memory. Computers almost always contain a small amount of read-only memory that holds instructions for starting up the computer. Unlike RAM, ROM cannot be written to more than one time. PROM is an acronym for programmable read-only memory. A PROM chip is a memory chip on which you can store data or a program. Once the PROM has been used, you cannot wipe it clean and use it to store something else. Like ROMs, PROMs are non-volatile. EPROM is an acronym for erasable programmable read-only memory. An EPROM is a special type of PROM that can be erased by exposing it to ultraviolet light. EEPROM is an acronym for electrically erasable programmable read-only memory. An EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Accordingly, there are different types of memory hardware wherein one or more of them may be employed within a computer.
As noted above, in addition to memory hardware there is storage and associated storage hardware, also known as secondary storage. It is known in the art to store data on hardware, such as tapes, disk, optical storage, flash drives, etc. Secondary storage is different from memory hardware in that it is not directly accessible by the central processing unit. The computer usually uses its input/output channels to access secondary storage. Secondary storage does not lose data when the device is powered down. Accessing data from secondary storage is not as fast as accessing data from main memory.
There are techniques employed to manage power consumption of computer machines. Such techniques include reducing the operating speed of a hard disk to an idle state when access to the hard disk is not required and increasing the operating speed of the hard disk when access to the hard disk is required. Management of the speed of the hard disk enables greater operating efficiency of a computer machine. It is also known in the art to manage power consumption of a computer machine by managing the speed of a processor. For example one of the features present on laptop and desktop computers is the ability of the computer to be placed in a low power state of operation, such as Suspend and Hibernate. In the Suspend state, power to the processor is turned off, but the memory remains intact. This is a state of low power consumption. When the operator of the computer wants to regain usage of the hardware accessory, the operator must Restore full power to the processor. A full system restart is not necessary since the memory remains intact. In addition to the Suspend state, the computer may also be placed in the low power state of Hibernate, where power to the computer is turned off following placement of memory to disk. In general, it is less time consuming to enter the Suspend state and restore power to the computer or to enter the Hibernate state and resume power to the computer, than to terminate power to the computer and restart the full system at a later time. Accordingly, there are tools that are employed to manage the power consumption through control of the operating state of the processor.
As noted above, current power management techniques address management of the processor speed. However, the prior art does not address power consumption of hardware memory devices in the computer. Current architectures include the ability to measure power consumption and thermal characteristics of components within the system. Accordingly, there is a need to expand power management from beyond the processor and to apply it to other hardware elements in the computer system and to bring power management into the domain of the operating system.