Four-slot asynchronous communication mechanism with increased throughput

A computer-accessible memory medium storing program instructions executable to:

• read a first one or more bits from a data structure on a host, wherein the data structure comprises a first pair of slots, a second pair of slots and the first one or more bits, and wherein the first one or more bits indicate that the first pair of slots has been read from most recently by the host;
• wherein the memory medium stores a second one or more bits that indicate that a first slot of the second pair of slots has been written to more recently;
• read the second one or more bits;
• increment a value of a counter to a latest value, wherein the value of the counter is useable to indicate which slot has been written to most recently;
• write first data to a second slot of the second pair of slots based on the first one or more bits indicating that the first pair of slots has been read from most recently by the host and the second one or more bits indicating that the first slot of the second pair of slots has been written to more recently;
• wherein the first data includes the latest value of the counter;
• update the second one or more bits to indicate that the second slot of the second pair of slots has been written to more recently.

A client device which transfers data to a remote host, the client device comprising:

• a memory medium;
• a functional unit coupled to the memory medium, configured to:
• read a first one or more bits from a data structure on the remote host, wherein the data structure comprises a first pair of slots, a second pair of slots and the first one or more bits, and wherein the first one or more bits indicate that the first pair of slots has been read from most recently by the host;
• read a second one or more bits from the memory medium, wherein the second one or more bits indicate that the first slot of the second pair of slots has been written to more recently;
• increment a value of a counter to a latest value, wherein the counter is stored on the memory medium and the value of the counter is useable to indicate which slot has most recently been written to;
• write first data to a second slot of the second pair of slots based on the first one or more bits indicating that the first pair of slots has been read from most recently by the host and the second one or more bits indicating that the first slot of the second pair of slots has been written to more recently, wherein the first data includes the latest value of the counter;
• update the second one or more bits on the memory medium after writing to the second slot of the second pair of slots to indicate that the second slot of the second pair of slots has been written to more recently.

A system, comprising

• A host system, comprising a first processor and a first memory medium;
• A client device, comprising a functional unit, a second memory medium, and a counter;
• wherein the host system and the client device are electrically coupled to allow communication;
• wherein the first memory medium comprises a data structure, wherein the data structure comprises a first pair of slots, a second pair of slots, and a first one or more bits, wherein the first one or more bits indicate which pair of slots the host system has read from most recently;
• wherein the counter is useable to indicate which slot has been most recently written to by the client device;
• wherein the second memory medium comprises a second one or more bits, wherein the second one or more bits indicate which pair of slots has been written to by the client device most recently, and which slot of each pair of slots has been written to by the client device more recently;
• wherein the functional unit is configured to:
• read the first one or more bits from the first memory medium;
• read the second one or more bits from the second memory medium;
• increment the counter to a latest value;
• write data to a slot in the data structure on the first memory medium of the host system, wherein the slot is determined based on reading from the first one or more bits and the second one or more bits, wherein the slot comprises whichever slot has not been written to more recently of the pair of slots which has not been read from most recently, and wherein the data includes the latest value of the counter;
• update the second one or more bits to reflect any change in which pair of slots has been written to by the client device most recently and which slot of each pair of slots has been written to by the client device more recently after writing data to the slot;
• wherein the first memory medium further comprises program instructions executable by the first processor to:
• determine which pair of slots has been written to by the client device most recently based on the counter value for each slot of the data structure;
• update the first one or more bits to indicate that the host system has most recently read from the pair of slots most recently written to by the client device;
• determine which slot in the determined pair of slots has been written to most recently based on the counter value for each slot in the determined pair of slots;
• read data from the slot determined to have been written to by the client device most recently.

A computer-accessible memory medium comprised on a client device, wherein the memory medium comprises program instructions executable to transfer data to a host, wherein the host stores a data structure comprising a first pair of slots and a second pair of slots, wherein the program instructions are executable by the client device to:

• read first information from the host, wherein the first information indicates a status of read operations from the data structure by the host;
• read second information from the memory medium, wherein the second information indicates a status of write operations to the data structure by the client device;
• determine which slot of the data structure should be written to based on the first information and the second information;
• increment a value of a counter to a latest value, wherein the value of the counter is useable to indicate which slot has been written to most recently;
• write first data to the determined slot, wherein the first data includes the latest value of the counter;
• update the second information to indicate that the determined slot has been written to most recently,
• wherein the first information indicates from which pair of slots the host has most recently read, and wherein the second information indicates which slot of each pair of slots has been written to most recently by the client device.