Selection of Units for Garbage Collection in Flash Memory

An apparatus, comprising:

• a plurality of garbage collection units each comprising a plurality of flash memory units;
• a controller configured to perform a garbage collection operation on the garbage collection units, the controller causing the apparatus to:
• form a data structure referencing a garbage collection metric for each of a plurality of associated garbage collection units of a flash memory device, each garbage collection metric based on one or more device state characteristics of the associated garbage collection unit;
• in response to a threshold change in the one or more device state variables, sort a region of interest within the data structure based on the garbage collection metrics;
• and
• select one or more garbage collection units for garbage collection operations from the sorted region of interest.

A method comprising:

• maintaining a collection of elements that each comprise a garbage collection metric of a respective one of a plurality of garbage collection units, wherein the garbage collection metrics are based on one or more device state variables;
• forming a data structure comprising a plurality of second elements that are each associated with one of the elements of the collection, wherein the garbage collection units are selected for a garbage collection operation based on an order of the second elements within the data structure;
• and
• in response to determining a threshold change in the device state variables, sorting only a region of interest within the data structure based on the garbage collection metrics of the second elements in the region of interest.