Monitoring tests and viewing results

Linpack

Linpack is an industry standard cluster performance test used for submitting numbers to the Top 500 Supercomputers list. The test is implemented to run separately on each node using all CPU cores and about 80% or less of memory. Two parameters need to be specified: Mem(GB) and Mem(%). Mem(GB) is the total memory in gigabytes on each node, and Mem(%) is the percentage of total memory used in the test. By default, this test will not give cluster-wide performance, but it exercises CPU and memory at the same time, and it provides another set of numbers you can use to compare the performance among the cluster nodes. The amount of memory required is set to auto by default – this will run each node at the specified percentage of the memory available. For example, using auto and 80%, a 2 GB node will use 80% of 2 GB, while a 16 GB node will use 80% of 16 GB. The amount of memory used on any head node is adjusted to allow for increased memory consumption on head nodes. The default Linpack test run performs three iterations of the test using the same input data for each run. To limit the number of iterations to one, select the Single Pass option.

Netperf

Netperf is a benchmark used to measure network performance (for example, GigE and 10GigE). It currently provides tests for unidirectional throughput. You must select TCP (TCP_STREAM) or UDP (UDP_STREAM) protocol. The first half of the selected nodes receives messages from the second half. For example, in a 10 node cluster, node 5 sends to node 0; node 6 sends to node 1; node 7 sends to node 2; and so on. An even number of nodes must be selected to run this test.

InfiniBand verbs tests

This is a collection of InfiniBand verbs bandwidth/latency performance tests provided with OFED. Verbs-layer performance is usually higher than what is reported by the MPI-level tests, such as Pallas. The InfiniBand verbs test (shown in the GUI as ib_send_bw) is selected by choosing the test name from the first two spin boxes. These selections will update the test button used to run the test. Test options can be specified in the Options box. Please refer to the documentation for each individual InfiniBand verbs test for the available options. Some of the useful options include –ato include all message sizes, and –bfor bi-directional test. The node settings are identical to the Netperf test above. These tests are only available with the InfiniBand interconnect on non-QLogic IB hardware.

Deviation test

This test measures the consistency of bandwidth and latency between nodes using MPI over IB. The node settings are identical to the Netperf test above. This test is only available with the InfiniBand interconnect on QLogic IB hardware.

The nodes monitoring window

The bottom left window on the Cluster Test interface is the nodes monitoring window. It can be resized to give more space to the test output window.

This window indicates whether a node is active (online) or inactive (offline).

Monitoring tests and viewing results 15