Low latency bypass buffer

Apparatus for buffering received data transaction requests, said apparatus comprising:

• shared buffer means for storing, in order of reception time at said shared buffer means, data transaction requests received from one or more data transaction sources;
• low latency identifying means for identifying low latency data transaction requests associated with low latency handling from among said data transaction requests received from said one or more data transaction sources and stored in said shared buffer means;
• output selection means for selecting a data transaction request for output from said shared buffer means and for operating in a selectable one of:
• a bypass mode in which said data transaction request selected for output is one of:
• (a) if any low latency data transaction requests are stored in said shared buffer means, an earliest received low latency data transaction stored in said shared buffer means;
• and
• (b) if no low latency data transaction requests are stored in said shared buffer means, an earliest received data transaction request among any data transaction requests stored in said shared buffer means;
• and
• a non-bypass mode in which said data transaction request selected for output is an earliest received data transaction request among any data transaction requests stored in said shared buffer means;
• rate detection means for detecting a rate of output of low latency data transaction requests from said shared buffer means;
• and
• bypass control means for comparing said rate with a threshold value and to control said output selection means to operate in one of:
• said bypass mode when said rate is less than said threshold value;
• and
• said non-bypass mode when said rate is greater than said threshold value.

A method of buffering received data transaction requests, said method comprising the steps of:

• storing in shared buffer circuitry, in order of reception time at said shared buffer circuitry, data transaction requests received from one or more data transaction sources;
• identifying low latency data transaction requests associated with low latency handling from among said data transaction requests received from said one or more data transaction sources and stored in said shared buffer means;
• selecting a data transaction request for output from said shared buffer circuitry using a selectable one of:
• a bypass mode in which said data transaction request selected for output is one of:
• (a) if any low latency data transaction requests are stored in said shared buffer circuitry, an earliest received low latency data transaction stored in said shared buffer circuitry;
• and
• (b) if no low latency data transaction requests are stored in said shared buffer circuitry, an earliest received data transaction request among any data transaction requests stored in said shared buffer circuitry;
• and
• a non-bypass mode in which said data transaction request selected for output is an earliest received data transaction request among any data transaction requests stored in said shared buffer circuitry;
• detecting a rate of output of low latency data transaction requests from said shared buffer circuitry;
• and
• comparing said rate with a threshold value and to control said steps of selecting to operate in one of:
• said bypass mode when said rate is less than said threshold value;
• and
• said non-bypass mode when said rate is greater than said threshold value.