Deferred write back based on age time

A method, comprising:

• monitoring an age time for a cached instance of data stored on a data cache, an original instance of the data being stored on a non-volatile data storage device;
• modifying, based on the age time, a cache table entry for the cached instance to indicate that the cached instance is a candidate for a deferred write back period;
• monitoring for the deferred write back period based on data activity of the data cache;
• and
• during the deferred write back period, causing the cached instance to be written back from the data cache to the non-volatile data storage device if the cache table entry indicates that the cached instance has been modified and if the cache table entry indicates that the cached instance is a candidate for the deferred write back period.

A computer system, comprising:

• a non-volatile memory to store an original instance of a data;
• a volatile memory to store a cached instance of the data;
• and
• a memory management unit (MMU) to:
• monitor an age time for the cached instance;
• based on the age time, modify a cache table entry for the cached instance to indicate that the cached instance is a candidate for a deferred write back period;
• monitor for the deferred write back period based on activity of the MMU;
• and
• during the deferred write back period, cause the cached instance to be written back from the volatile memory to the non-volatile memory based on whether the cache table entry indicates that the cached instance has been modified and based on whether the cache table entry indicates that the cached instance is a candidate for the deferred write back period.