Device, system, and method of handling transactions
View Patent ↗Some embodiments include, for example, devices, systems, and methods of handling transactions. In some demonstrative embodiments, an apparatus to handle transactions in a computing system may include a master unit to arbitrate between read and write requests to be issued over a request bus according to at least first and second arbitration schemes. A first ratio between read and write requests issued by the master unit according to the first arbitration scheme may be different from a second ratio between read and write requests issued by the master unit according to the second arbitration scheme.
1. An apparatus to handle transactions in a computing system, the apparatus comprising:
a slave unit;
a request bus;
a read bus for communicating read data from the slave unit;
a master unit connected to the read bus and operative to issue read requests, the read requests comprising immediate read requests, and delayed read requests and to issue write requests over the request bus to the slave unit, wherein the immediate read requests have the read data available from the slave unit at relatively short latencies and are performed as a single request and the delayed read requests have read data available from the slave unit at relatively long latencies and are performed by initiating respective first requests over the request bus and thereafter issuing second requests over the request bus to fetch the read data from the slave unit; and
an arbiter adapted to select, responsively to a non-ideal utilization of the read bus, one of at least first and second arbitration schemes for issuing the read requests and the write requests, wherein a first ratio between the read requests and the write requests according to the first arbitration scheme is different from a second ratio between the read requests and the write requests according to the second arbitration scheme, the master unit cooperative with the arbiter to obtain a balance between read transactions with the slave unit and write transactions with the slave unit by issuing the delayed read requests in accordance with a selected one of the first arbitration scheme and the second arbitration scheme.
2. The apparatus of claim 1 , further comprising:
a read queue to maintain a plurality of read requests; and
a write queue to maintain a plurality of write requests, wherein making a comparison comprises determining a relation between a number of the plurality of write requests in the write queue and a number of the plurality of read requests in the read queue.
3. The apparatus of claim 2 , wherein the master unit is operative to switch from the first arbitration scheme to the second arbitration scheme when a difference between the number of the plurality of write requests and the number of the plurality of read requests is equal to or greater than a predefined threshold.
4. The apparatus of claim 2 , wherein the master unit is operative to switch from the second arbitration scheme to the first arbitration scheme, when a difference between the number of the plurality of read requests and the number of the plurality of write requests is equal to or greater than a predefined threshold.
5. The apparatus of claim 1 , wherein the first ratio is different from one, and wherein the second ratio is equal to one.
6. The apparatus of claim 1 , wherein the first ratio comprises a ratio of two read requests to one write request, and wherein the second ratio comprises a ratio of one read request to one write request.
7. A method of handling transactions in a computing system, the method comprising:
issuing read requests comprising immediate read requests having read data available from on a read bus from a slave unit at relatively short latencies and delayed read requests having read data available from the slave unit at relatively long latencies, the immediate read requests being issued as single requests over a request bus and the delayed read requests being issued as respective first requests over the request bus and thereafter as second requests over the request bus to fetch the read data from the slave unit;
selecting, responsively to a non-ideal utilization of the read bus, one of at least first and second arbitration schemes, wherein a first ratio between the read requests and write requests issued according to the first arbitration scheme is different from a second ratio between the read requests and the write requests issued according to the second arbitration scheme; and
performing delayed read transactions by issuing the delayed read requests on the request bus in accordance with a selected one of the first arbitration scheme and the second arbitration scheme to fetch the read data from the slave unit, the delayed read transactions comprising first read requests and second read requests over the request bus.
8. The method of claim 7 , comprising:
maintaining a plurality of read requests in a read queue;
maintaining a plurality of write requests in a write queue; and
switching between the first and second arbitration schemes based on a relation between a number of the plurality of write requests in the write queue and a number of the plurality of read requests in the read queue.
9. The method of claim 8 , wherein issuing the delayed read requests comprises switching from the first arbitration scheme to the second arbitration scheme when a difference between the number of the plurality of write requests and the number of the plurality of read requests is equal to or greater than a predefined threshold.
10. The method of claim 8 , wherein issuing the delayed read requests comprises switching from the second arbitration scheme to the first arbitration scheme, when a difference between the number of the plurality of read requests and the number of the plurality of write requests is equal to or greater than a predefined threshold.
11. The method of claim 7 , wherein the first ratio is different from one, and wherein the second ratio is equal to one.
12. The method of claim 7 , wherein the first ratio comprises a ratio of two read requests to one write request, and wherein the second ratio comprises a ratio of one read request to one write request.