Method and apparatus for providing cacheable data to a peripheral device

A cache controller couplable to a cache and to a memory, the cache comprising a cache line, the cache controller comprising:

• logic to provide data from the cache to the memory when both (a) the cache line is full and (b) a streaming memory attribute of a portion of a memory subsystem is set wherein a marked streaming memory attribute represents that corresponding data is for a graphics processor, wherein:
• the cache controller is operative to suppress cache prefetching when the streaming memory attribute of a portion of a memory subsystem is set;
• and
• the cache controller is operative to prefetch other data from the memory into the cache line when the streaming memory attribute is not marked.

A computer system comprising:

• a memory;
• a cache including a cache line and a streaming memory attribute;
• and
• a cache controller coupled to provide data from the cache to the memory when both (a) the cache line is full and (b) the streaming memory attribute is set, wherein:
• the cache controller is operative to suppress cache prefetching when the streaming memory attribute of a portion of a memory subsystem is set.

A computer system comprising:

• a cache;
• a memory;
• a circuit operable to load a streaming memory attribute from a cache driver into a cache attribute table upon detecting a configuration of the computer system wherein a marked streaming memory attribute represents that corresponding data is for a graphics processor;
• and
• a cache controller operable to access the cache attribute table upon detecting an access to the cache and to selectively suppress prefetching according to the streaming memory attribute, wherein:
• the cache controller is operable to
• access the cache attribute table upon detecting that a write instruction fills a cache line by writing data to a last cache location within the cache line;
• to suppress prefetching when the streaming memory attribute is set;
• and
• to permit prefetching when the streaming memory attribute is not set.

A method of accessing a memory, the method comprising:

• determining whether an address fills a cache line;
• determining whether a streaming memory attribute corresponding to the address is set, wherein a marked streaming memory attribute represents that corresponding data is for a graphics processor, and
• when the address fills a cache line and the streaming memory attribute memory attribute corresponding to the address is set,
• copying data corresponding to the address and residing in the cache line into the memory;
• and
• making the cache line available for accepting new data.