From 445076e54533b4b024b4551dafad79f1ba6ab268 Mon Sep 17 00:00:00 2001 From: Haihan Jiang Date: Tue, 26 May 2026 20:28:38 -0700 Subject: [PATCH 1/3] Clarify CPU frequency stability guidance --- docs/reducing_variance.md | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/docs/reducing_variance.md b/docs/reducing_variance.md index 364f4af15b..22d9cab9da 100644 --- a/docs/reducing_variance.md +++ b/docs/reducing_variance.md @@ -35,7 +35,12 @@ by running this command: cpupower frequency-info -o proc ``` -The benchmarks you subsequently run will have less variance. +The benchmarks you subsequently run will usually have less variance. Do not +assume that the governor setting is the only frequency control that matters: +boost settings, SMT/Hyperthreading, firmware, and kernel behavior can still +change the observed CPU frequency. For sensitive measurements, monitor the +actual per-CPU frequency during the benchmark run and keep the configuration +that is stable on that machine. From 5e5d81aab8d36de2e7617714fa38d7b7eb736074 Mon Sep 17 00:00:00 2001 From: Haihan Jiang Date: Fri, 29 May 2026 17:19:22 -0700 Subject: [PATCH 2/3] Remove duplicated CPU variance guidance --- docs/reducing_variance.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/docs/reducing_variance.md b/docs/reducing_variance.md index 22d9cab9da..8889c7891c 100644 --- a/docs/reducing_variance.md +++ b/docs/reducing_variance.md @@ -35,8 +35,8 @@ by running this command: cpupower frequency-info -o proc ``` -The benchmarks you subsequently run will usually have less variance. Do not -assume that the governor setting is the only frequency control that matters: +Do not assume that the governor setting is the only frequency control that +matters: boost settings, SMT/Hyperthreading, firmware, and kernel behavior can still change the observed CPU frequency. For sensitive measurements, monitor the actual per-CPU frequency during the benchmark run and keep the configuration From 1c694fbe8e389af09ab1c6b52fd5b9980aeb0ae0 Mon Sep 17 00:00:00 2001 From: Haihan Jiang Date: Sat, 30 May 2026 15:43:32 -0700 Subject: [PATCH 3/3] Avoid duplicating variance guidance --- docs/reducing_variance.md | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/docs/reducing_variance.md b/docs/reducing_variance.md index 8889c7891c..566b9aa73a 100644 --- a/docs/reducing_variance.md +++ b/docs/reducing_variance.md @@ -35,12 +35,8 @@ by running this command: cpupower frequency-info -o proc ``` -Do not assume that the governor setting is the only frequency control that -matters: -boost settings, SMT/Hyperthreading, firmware, and kernel behavior can still -change the observed CPU frequency. For sensitive measurements, monitor the -actual per-CPU frequency during the benchmark run and keep the configuration -that is stable on that machine. +For other CPU-frequency and system-noise sources that can still affect +measurements, see the reducing variance section below.