BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 illustrates one example of a system for flow-control concurrency to prevent excessive packet loss, in accordance with the disclosed invention; and
FIG. 2 illustrates one example of a method for a fine grained concurrency parameter of the system in FIG. 1;
FIG. 3 illustrates one example of a method for an alternative fine grained concurrency parameter of the system in FIG. 1; and
FIG. 4 illustrates one example of a method for an alternative fine grained concurrently parameter of the system in FIG. 1.
The detailed description explains an exemplary embodiment of the invention, together with advantages and features, by way of example with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
Figure illustrates a portion of computing network including a plurality of nodes. Only two nodes are shown for ease of illustration, but it is understood that the computing network includes numerous nodes, which can transmit data to multiple nodes and receive data from multiple nodes. For simplicity, node 20 is referenced as a transmitter node 20 and node 40 is referenced as receiver node 40, although it is understood that all nodes may both send and receive data. Nodes 20 and 40 are processor-based devices and execute computer programs to perform the processes described herein.
Referring to FIG. 1, a system for flow-control concurrency to prevent excessive packet loss is shown. At least one transmitter node 20 is included with the system 10. Each transmitter node 20 is configured to transmit data. A first flow-control device 22 is communicatively coupled to the at least one transmitter node 20. The first flow-control device 22 may be implemented through a software application executing on node 20. The first flow-control device 22 is configured to limit the number of concurrent data replies that are sent by the at least one transmitter node 20. This ensures that the resources on the sending side will not be over-run.
The system further includes at least one receiver node 40. Each receiver node 40 is configured to receive data transferred by the at least one transmitter node 20. Each receiver node 40 is communicatively coupled to the at least one transmitter node 20 via the communication network 30. A second flow-control device 42 is communicatively coupled to the at least one receiver node 40. The second flow-control device 42 may be implemented through a software application executing on node 40. The second flow-control device 42 is configured to limit the number of concurrent data requests received by the at least one receiver node 40. This ensures that resources on the receiving side will not be over-run.
Prior to the transmission of data for a write request, each transmitting node 20 transmits a request to send data to the at least one receiving node 40. The at least one receiving node 40 is configured to receive the data transmitted by the at least one transmitting node 20. The at least one receiving node 40 is further configured to accept the request to send data and to transmit a reply to the at least one transmitting node 20 that pertains to the request to send data that was transmitted by the at least one transmitter node 20. The second flow-control device 42 is configured to limit the number of concurrent replies to send data. This ensures that the resources on the receiving side will not be overrun.
The first flow-control and the second flow-control device 22 and 42, respectively, are configured to adhere to fine grained concurrently parameters that are part of the subsystem configuration commands. These parameters include (i) maximum read count, (ii) maximum read response count, and (iii) maximum write count.
Referring to FIG. 2, a method pertaining to the usage of the fine-grained concurrency parameter of maximum read count is shown. Maximum read count specified the number of concurrent outstanding reads that are permitted at a client node (receiver node). This provides the ability to limit the amount of data being received by a client node in order to prevent resource overruns. As read requests come into a node, provided the number of outstanding reads is less that the maximum read count they are immediately processed. If the number of outstanding reads is equal or greater than the maximum read count, then the read remains queued for later processing. Stepwise, starting at step 100 a check for work is performed. At step 110 a read request is began. At step 120 the quantity of the outstanding reads is compared to the maximum read count. If the quantity of the outstanding reads is equal to or greater than the maximum read count, the read request is queued at step 130. Otherwise, the request is processed at step 140. At step 150, the read request is terminated. At step 160 reads are checked, if the read is queued at step 170 the request is unqueued, otherwise the method starts over again at step 100.
Referring to FIG. 3, a method pertaining to the usage of the fine grained concurrency parameter of maximum read response count is shown. Maximum read response count specifies the number of concurrent outstanding read responses that are permitted at a transmitter node. This provides a mechanism to limit the amount of data being sent by a transmitter node in order to prevent resource overruns. On a read request, the transmitter node will read the data from the disk and then check the number of outstanding read responses. If the number of outstanding read responses is less than the maximum read response count, then immediately send the data to the client node (receiver). Otherwise, queue the request for later processing. Stepwise, starting at step 200, a check for work is performed. Then at step 210, the disk is read. At step 220 the outstanding responses are checked. If the outstanding responses are equal to the maximum response count, the response is queued at step 230. Otherwise the response is dispatched at step 240. At step 250 the responses are checked, if the responses are queued then at step 260 the response shall be unqueued, otherwise the method starts over again at step 200.
Referring to FIG. 4, a method pertaining to the usage of the fine-grained concurrency parameter of maximum write count flow is shown. On a write request, the receiver node will allocate buffers and check the number of outstanding write requests. If the number of outstanding write requests is less than the maximum write count, then immediately send a signal to the client node requesting the data. Otherwise, queue the request for later processing. Stepwise, starting at step 300 a check for work is performed. At step 310 a write request is performed. At step 320 a check of the outstanding writes is performed. If the outstanding write equals the maximum write count the write request is queued at step 330. Otherwise, data is acquired from the client node at step 340. Subsequently, at step 350 the writes are checked. If the check discloses that the writes are queued, at step 360 the writes shall be unqueued. Otherwise the method starts over again at step 300.
While the preferred embodiment to the invention has been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.
Patent Application
20080049617
