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Description of problem:
The RHEL 7.5 kernel currently does not include support for the Cavium ThunderX2 processor's SoC performance counters. We need access to these counters and request that the following set of patches be ported to the RHEL Linux kernel:
* Lkml thread: https://lkml.org/lkml/2018/6/21/35
* 4.17 onwards: https://patchwork.kernel.org/patch/10479191/
* 4.16 backport: https://github.com/cavium/thunderx-linux/commits/thunder-4.16-drop4
HPE has made this request separately, BZ#1622200
Version-Release number of selected component (if applicable):
RHEL 7.5 Linux kernel
How reproducible:
This test requires RHEL7.5 running on a Cavium ThunderX2 server. Use perf to measure the aggregate bytes moved to and from main memory using the Cavium ThunderX2 memory controller's counters. Example perf command is listed below.
Steps to Reproduce:
1. perf stat -e dmc/read_64b_txns/,dmc/write_txns/ <program>
Actual results:
invalid or unsupported event: 'dmc/read_64b_txns/,dmc/write_txns/'
Expected results:
Success, a count of the total bytes moved to and from main memory. Combined with a time measurement, this can be used to calculate the actual memory bandwidth achieved.
Additional info:
This feature is needed for the upcoming Arm-based Astra supercomputer to be installed at Sandia National Laboratories in September 2018. The POR is to run RHEL7.5 on this system, but support for these performance counters are needed.