Controller configured to control timing of access request according to density of burst access and access load

1. A controller which controls a timing of transmitting an access request that has been received from an initiator, the controller comprising:

transmitting and receiving circuitry configured to receive an access request related to burst accesses from a first initiator that is connected via a first bus to, and adjacent to, the transmitting and receiving circuitry and configured to transmit the access request to a second bus implemented as a network; and

a transmission interval controller configured to control the timing of transmitting the access request that has been received from the first initiator according to density of the burst accesses during a period in which the burst accesses continue and an access load on the second bus, said density of the burst accesses determined from the equation

T

b

N

p

*

T

p

,

where T b is one burst period in which the burst accesses are generated, N p is the number of times of accesses generated within a single burst period, and T p is number of cyles to transfer a single packet.

2. The controller of claim 1 , wherein the transmission interval controller calculates the density of the burst accesses based on how many times the access requests have been received from the first initiator during the period in which the burst accesses continue.

3. The controller of claim 2 , wherein either a second initiator or a target is connected to the second bus, and

wherein the transmission interval controller obtains, as the access load on the second bus, a latency that is the amount of time that it takes for a response to the access request that has been transmitted to either the second initiator or the target to come back.

4. The controller of claim 3 , wherein if the value of a permissible delay, which is the maximum amount of delay permitted by an access request from the first initiator, is not negative, the transmission interval controller obtains the latency and controls the timing of transmitting the access request that has been received from the first initiator.

5. The controller of claim 4 , wherein the transmission interval controller calculates the value of the permissible delay based on a predetermined cycle, the number of remaining cycles, and the number of unprocessed access requests.

6. The controller of claim 4 , wherein the transmission interval controller calculates the latency between the first initiator and the second initiator or target that is connected to the second bus, and if the latency is greater than at least one predetermined threshold value, extends the transmission interval so as to delay the timing of transmitting the access request that has been received from the first initiator.

7. The controller of claim 5 , wherein the transmission interval controller calculates a second transmission interval by adding a value associated with the density of the burst accesses to a first transmission interval currently set, and if the second transmission interval is smaller than the value of the permissible delay, controls the timing of transmitting the access request that has been received from the first initiator based on the second transmission interval.

8. The controller of claim 4 , wherein the transmission interval controller calculates the latency between the first initiator and the second initiator or target that is connected to the second bus, and if the latency is equal to or smaller than at least one predetermined threshold value, shortens the transmission interval so as to accelerate the timing of transmitting the access request that has been received from the first initiator.

9. The controller of claim 5 , wherein the transmission interval controller calculates a second transmission interval by subtracting a value associated with the density of the burst accesses from a first transmission interval currently set, and if the second transmission interval is smaller than the value of the permissible delay, controls the timing of transmitting the access request that has been received from the first initiator based on the second transmission interval.

10. The controller of claim 7 , wherein if the second transmission interval is equal to or greater than the value of the permissible delay, the transmission interval controller controls the timing of transmitting the access request that has been received from the first initiator based on the value of the permissible delay.

11. The controller of claim 9 , wherein if the second transmission interval is equal to or greater than the value of the permissible delay, the transmission interval controller controls the timing of transmitting the access request that has been received from the first initiator based on the value of the permissible delay.

12. The controller of claim 10 , wherein the transmission interval controller prohibits the first initiator from issuing access requests for a period of time corresponding to the sum of the second transmission interval and the time it takes to transfer a transaction.

13. The controller of claim 11 , wherein the transmission interval controller prohibits the first initiator from issuing access requests for a period of time corresponding to the sum of the second transmission interval and the time it takes to transfer a transaction.