Intel Memory Bandwidth Monitoring (MBM) counters may report system memory bandwidth incorrectly on some Intel processors. The errata are reported in erratum SKX99 [1], erratum BDF102 [2] and RDT reference manual [3].
The errata are worked around using a correction factor table. Since the correction factor table is not publicly documented anywhere, it's documented in Documentation/x86/resctrl.rst along with the errata. 1. Erratum SKX99 in Intel Xeon Processor Scalable Family Specification Update: http://web.archive.org/web/20200716124958/https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-spec-update.html 2. Erratum BDF102 in Intel Xeon E5-2600 v4 Processor Product Family Specification Update: http://web.archive.org/web/20191125200531/https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/xeon-e5-v4-spec-update.pdf 3. The errata in Intel Resource Director Technology (Intel RDT) on 2nd Generation Intel Xeon Scalable Processors Reference Manual: https://software.intel.com/content/www/us/en/develop/articles/intel-resource-director-technology-rdt-reference-manual.html Change Log: v2: - Document the errata and the correction table in resctrl.rst (Boris). - Address various comments on patch 2 (Boris). - Change the documentation URLs to stable archive.org (Tony). Fenghua Yu (2): Documentation: x86: Rename resctrl_ui.rst and add two errata to the file x86/resctrl: Correct MBM total and local values Documentation/conf.py | 2 +- Documentation/x86/index.rst | 2 +- .../x86/{resctrl_ui.rst => resctrl.rst} | 82 ++++++++++++++++++ arch/x86/kernel/cpu/resctrl/core.c | 4 + arch/x86/kernel/cpu/resctrl/internal.h | 1 + arch/x86/kernel/cpu/resctrl/monitor.c | 83 ++++++++++++++++++- 6 files changed, 170 insertions(+), 4 deletions(-) rename Documentation/x86/{resctrl_ui.rst => resctrl.rst} (92%) -- 2.28.0
