Writing data to system memory in a data processing system in which cache line states are tracked

A system comprising:

• one or more masters, each master comprising one of a processor or a peripheral device;
• a system memory comprising a plurality of system memory banks, wherein
• each system memory bank comprises a plurality of unique rows, and
• each row corresponds to a region of the system memory;
• one or more cache memories, coupled to the one or more masters, and storing a plurality of cache lines, wherein
• each cache line is associated with a corresponding unique section of a row of the plurality of rows,
• each cache line is configured to store data associated with the corresponding unique section of a row for access by the one or more processors, and
• the one or more cache memories comprise one or more of a system cache and a dedicated cache associated with a corresponding processor;
• and
• a cache cleaning circuitry, coupled to the one or more cache memories, and configured to
• store a plurality of state indicators each associated with a corresponding cache line of the plurality of cache lines, wherein each state indicator comprises one of a dirty indication that the corresponding cache line is a candidate for writing data stored in the cache line to the corresponding unique section of the row or a clean indication that the corresponding cache line is not a candidate for writing data stored in the cache line,
• select a row having a number of state indicators comprising the dirty indication exceeding a threshold, and
• for the selected row, select one or more cache lines each having a corresponding state indicator comprising the dirty indication, write the data stored in the selected cache lines to the corresponding sections of the row, and store a clean indication in the state indicator,
• wherein the state indicator is stored in a tracking entry associated with the row, wherein the tracking entry comprises N state indicators of the plurality of state indicators associated with the cache lines associated with the row, in which N represents a number of cache lines needed to store all of the row.

A method comprising:

• determining whether one or more tracking entries comprise a number of dirty indications that exceeds a predetermined threshold, wherein
• each tracking entry comprises a plurality of cache line fields each having a corresponding cache line associated with a unique section of the same region of system memory, wherein the plurality of cache line fields includes N cache line fields in which N represents a number of cache lines needed to store all of the same region of system memory, and wherein each cache line field comprises:
• a dirty indication when the corresponding cache line is a candidate for writing data stored in the cache line to the associated unique section;
• and
• a clean indication when the corresponding cache line is not a candidate for writing data stored in the cache line to the associated unique section;
• selecting a tracking entry of the one or more tracking entries having a number of dirty indications exceeding the predetermined threshold;
• selecting a dirty cache line associated with the selected tracking entry;
• transmitting a transaction to a cache storing the selected cache line, wherein the transaction is configured to cause the cache to write the dirty data to a system memory;
• storing a clean indication in the state indicator corresponding to the selected tracking entry to indicate that the cache line is no longer a candidate for writing data to system memory;
• performing said selecting the cache line, transmitting, and storing for a predetermined number of cache lines;.
• storing a count of dirty indications for each tracking entry, wherein the dirty indications correspond to cache lines storing dirty data;
• and
• storing a new count of dirty indications for the associated tracking entry subsequent to said transmitting the transaction.