Connectivity Serdes Test Plugins Design, Switches and Parameters

This section describes plugin specific switches, however, it will not focus on the common switches although these switches will be mentioned here for the completeness of the command examples. To see the common plugin switches and parameters, refer to hl_qual Common Plugin Switches and Parameters.

Serdes Base Test Design Consideration and Responsibilities

The Serdes base test performs basic sanity tests on the Serdes, ensuring the following parts are tested:

  • Port connectivity

  • RX/TX data integrity

RX/TX data integrity is checked by pre-calculated random data and compared against a reference data. The default transmitted buffer size is 128MB to ensure a variety of transmitted data. During the test, the TX buffer is transmitted multiple times according to the test execution time you set. The test can check inter-box connectivity between the different devices using a pairs test. A pairs test takes all device pairs and runs a data integrity test on each pair of devices.

Serdes Base Test Testing Modes

The test plugin consists of the below sub-testing modes:

  • Pair test - This test runs over all available device pairs and tests connectivity.

  • ext_pairs - This test runs on external ports when applicable (which are used to scale-out between different boxes), in this mode these ports should be connected to an external switch.

  • All-Gather - This test runs over all available devices and computes the bandwidth of all-gather functionality.

  • All-Reduce - This test runs over all available devices and computes the bandwidth of all-reduce functionality.

NIC Base - Pass/fail Criteria

The pass/fail criteria is composed out of two sub-criteria:

  • Connectivity - The test fails if the destination rank does not respond.

  • The test fails if data is not received as expected, compared with the reference data.

The All-Gather and All-Reduce variants also calculate the BW for those network operations. You may run the test for a specific number of epochs and specific number of iteration per epoch. This will generate a MAX, MIN and Average BW per epoch which may expose BW instabilities to the time duration of the test.

Note

Both All-Gather and All-Reduce calculate BW for NIC port integrity only. They do not validate NIC port integrity. The user should pair as follows: test ext_pairs.

Serdes Base Test Plugin Switches and Parameters

First-gen Gaudi and Gaudi2 test variants differ in the test capabilities as demonstrated in the command line below:

hl_qual -gaudi|gaudi2 -c <pci bus id> [-i <inner loop iterations count>] [-ep <epoch count>] -rmod <serial | parallel>  [-dis_mon] [-mon_cfg <monitor INI path>]
-nic_base  -test_type <pairs, ext_pairs, allreduce, allgather> [-sz <size in bytes>] [-disable_ports <port list>] [-seed <seed>]

Switches and Parameters

Description

-test_type <test type>

Defines the test type and port configuration to be used in the user system. The different test type variants are:

  • pairs - This test checks the internal port connectivity.

  • ext_pairs - This test checks the internal port connectivity. [In this test case all internal ports interconnected between first-gen Gaudi devices are disabled.]

  • allgather - This test computes the all-gather bandwidth.

  • allreduce - This test computes the all-reduce bandwidth.

-nic_base

Serdes base test selector.

-sz

Send/receive buffer size in bytes.

-i

Iteration count For bandwidth computation.

-ep

Epoch count for bandwidth computation.

Note: This switch enables multiple epochs where each epoch is composed out of iterations and specified with -i switch This enables bandwidth calculation over long runs where the BW of each iteration is averaged over each epoch. The switch is applicable only for allgather and allreduce test modes.

--seed <seed>

Seed value for generating the transmit patterns. This is a 32 bit number with the following hexadecimal pattern xxxxxxxx (for example, abc123da). The default pattern is 5a5a5a5a5a.

disable_ports

Specify which ports to disable. Example: -disable_ports [1,2,3].

Examples:

-  ./hl_qual -gaudi -c all -rmod parallel -i 20 -nic_base -test_type pairs
-  ./hl_qual -gaudi -c all -rmod parallel -i 20 -ep 20 -nic_base -test_type allreduce

-  ./hl_qual -gaudi2 -c all -rmod parallel -i 50 -nic_base -test_type pairs
-  ./hl_qual -gaudi2 -c all -rmod parallel -i 50 -ep 100 -nic_base -test_type allreduce

First-gen Gaudi E2E Serdes Test Plugin Design Consideration and Responsibilities

The E2E serdes test is a multi-purpose test that can check any machine topology using a connectivity json that describes the machine’s unique connectivity and verifies both connectivity and BandWidth. The test runs on multiple Habana cards testing the ports simultaneously and reporting the collective bandwidth.

E2E Serdes Test Testing Modes

  • LOOPBACK - A serdes loopback communication test. This test runs on all external ports of the NICs and sends data through a loopback dongle from each external port back to itself. When running this test mode, the external ports must be connected (RX to TX) using a loopback dongle.

  • Internal - This mode sends data from each internal port to its connected port on a different first-gen Gaudi device.

  • All-lpbk - This mode simultaneously runs both the test on all the Internal ports and the test on all External ports. The test of the external ports is loopback and so all external ports must be connected (RX to TX) using a loopback dongle.

E2E - Pass/fail Criteria

The test currently fails only when there is no E2E connection between ports or loopback. The collective bandwidth is printed at the end of the test. When the test runs in Sanity mode using the -executeSanity flag it fails (in case bit error rate is higher than 0.1%).

First-gen Gaudi E2E Serdes Test Plugin Switches and Parameters

sudo hl_qual -gaudi -e2e -port_map <json name> -test_mode <all-lpbk | internal | external-lpbk> -c <pci bus id> -rmod <serial | parallel>  [-dis_mon] [-mon_cfg <monitor INI path>]

Switches and Parameters

Description

-e2e

Serdes base test selector.

-port_map <name of configuration name>

A file that defines the ports connectivity within the server box and which ports are external.

-test_mode <test type>

Defines the test type and port configuration to be used in the user system. The different test type variants are:

  • all-lpbk - Executes both internal and external tests. This mode only runs with -rmod parallel.

  • internal - Checks the internal port connectivity. This mode only runs with -rmod parallel.

  • external-lpbk - Tests all external ports, and assumes loopback dongle on all external ports.

 
sudo ./hl_qual -c all -test_mode all-lpbk -rmod parallel -e2e -port_map hls1.json -gaudi

The above command line runs the E2E test on both external ports with loopbacks dongles and internal ports. The network topology is defined by hls1.json.

Gaudi2 E2E Concurrency Test Plugin Design Consideration and Responsibilities

The E2E concurrency test plugin is a network bandwidth measurement test. The test calculates bandwidth per port and verifies transmission integrity. Since all verification processes run per port, the user can identify port connectivity issues very easily.

E2E - Pass/fail Criteria

The pass/fail criteria depends on the calculated BW and correctness. The criteria is 97GB/s.

Gaudi2 E2E Concurrency Test Plugin Switches and Parameters

hl_qual -gaudi2  -c <pci bus id>  -rmod <parallel>  [-dis_mon] [-mon_cfg <monitor INI path>] -e2e_concurrency [-disable_ports]

  • -e2e_concurrency - Test selector.

  • -disable_ports - Does not include specific ports to the pass/fail criteria.

./hl_qual -gaudi2 -c all -rmod parallel -dis_mon -e2e_concurrency

Gaudi2 BER Test Plugin Design Consideration and Responsibilities

The BER test plugin is a bit error rate measurement test. The BER test plugin calculates the port and lane bit error rate. To run this test, FEC must be disabled in the SerDes PHY retimers. After running this test, make sure to enable FEC for normal mode.

BER test - Pass/fail criteria

The pass/fail criteria depends on the calculated BER. The BER plugin pass/fail criteria for this mode is 0.0001.

Gaudi2 BER Test Plugin Switches and Parameters

hl_qual -gaudi2  -c <pci bus id>  -rmod <serial | parallel>  [-dis_mon] [-mon_cfg <monitor INI path>] -ber

  • -ber - BER test selector.

./hl_qual -gaudi2 -c all -rmod parallel -dis_mon -ber