From 60935c17e26ac2cfc4095bed02a6b4135c3e6d4a Mon Sep 17 00:00:00 2001 From: Srinivas Pandruvada Date: Fri, 16 Nov 2018 14:24:20 -0800 Subject: Documentation: intel_pstate: Clarify coordination of P-State limits Explain influence of per-core P-states and hyper threading on the effective performance. Signed-off-by: Srinivas Pandruvada Signed-off-by: Rafael J. Wysocki --- Documentation/admin-guide/pm/intel_pstate.rst | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst index ac6f5c597a56..ec0f7c111f65 100644 --- a/Documentation/admin-guide/pm/intel_pstate.rst +++ b/Documentation/admin-guide/pm/intel_pstate.rst @@ -495,7 +495,15 @@ on the following rules, regardless of the current operation mode of the driver: 2. Each individual CPU is affected by its own per-policy limits (that is, it cannot be requested to run faster than its own per-policy maximum and it - cannot be requested to run slower than its own per-policy minimum). + cannot be requested to run slower than its own per-policy minimum). The + effective performance depends on whether the platform supports per core + P-states, hyper-threading is enabled and on current performance requests + from other CPUs. When platform doesn't support per core P-states, the + effective performance can be more than the policy limits set on a CPU, if + other CPUs are requesting higher performance at that moment. Even with per + core P-states support, when hyper-threading is enabled, if the sibling CPU + is requesting higher performance, the other siblings will get higher + performance than their policy limits. 3. The global and per-policy limits can be set independently. -- cgit v1.2.3-59-g8ed1b