AWM Workload
We use the Application Workload Modeler (AWM) product, and an IBM-internal, pre-product version of AWM, to do connectivity measurements. We have editions of these two programs that run on Linux on System z. We also have editions that run on CMS.
For the Linux workloads, we run one Linux guest containing n AWM client processes, and we connect it to one Linux guest containing the corresponding n AWM server processes.
For the CMS workloads, we run n CMS client guests, each one running AWM. We connect those to n corresponding CMS server guests, each also running a copy of AWM.
The AWM workloads we use are request-response (RR), streaming (STR), and connect-request-response (CRR). The RR workload is like Telnet in that it is like an interactive session where the client connects, then small amounts of data are sent and received, then disconnects when finished. The STR workload is like FTP. The client connects, then a large amount of data is sent (or received) with a small amount of data in the response. Again the client disconnects when finished. The CRR workload is similar to a web connection where the client connects to the server, sends a request, receives a moderately-sized response, and then disconnects. This is repeated as many times as requested by the workload input. All three workloads are run with zero think time.
Our connectivity measurements for RR consist of the client side sending 200 bytes to the server and the server responding with 1000 bytes. This interaction is repeated for 200 seconds. The STR workload consists of the client sending 20 bytes to the server and the server responding with 20 MB. This sequence is repeated for 400 seconds. The CRR workload consists of the client connecting, sending 64 bytes to the server, receiving 8K from the server and disconnecting. This is repeated for 200 seconds.
A complete set of runs is done for each of the workloads shown in the following table, varying the maximum transmission unit (MTU) size. The connections referred to in the table are sometimes also referred to as client-server pairs, since the connection is between a client and a server.
| Device Type | Workload | MTU sizes we use | Number of connections |
|---|---|---|---|
| Real HiperSockets | RR | 8192 | 1, 10, 50 |
| STR | 8192, 56K | 1, 10, 50 | |
| Guest LAN HiperSockets | RR | 8192 | 1, 10, 50 |
| STR | 8192, 56K | 1, 10, 50 | |
| Real QDIO | RR | 1492 | 1, 10, 50 |
| STR | 1492, 8992 | 1, 10, 50 | |
| Guest LAN QDIO | RR | 1492 | 1, 10, 50 |
| STR | 1492, 8992 | 1, 10, 50 | |
| VSwitch | RR | 1492 | 1, 10, 50 |
| STR | 1492, 8992 | 1, 10, 50 | |
| IUCV | RR,CRR,STR | 1492, 8992, 16384, 32760, 57344 | 1, 10, 20, 50 |
| Virtual CTC | RR,CRR,STR | 1492, 8992, 16384, 32760 | 1, 10, 20, 50 |
| ESCON CTC | RR,CRR,STR | 1492, 8992, 16384, 32760 | 1, 10, 20, 50 |