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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2018-11-17 01:24:20 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-11-30 00:31:58 +0300
commit60935c17e26ac2cfc4095bed02a6b4135c3e6d4a (patch)
treea9df60a36d2e87471f1817508d1ca11e9609fd2f /Documentation/admin-guide/pm
parentaf3b7379e2d709f2d7c6966b8a6f5ec6bd134241 (diff)
downloadlinux-60935c17e26ac2cfc4095bed02a6b4135c3e6d4a.tar.xz
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 <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/admin-guide/pm')
-rw-r--r--Documentation/admin-guide/pm/intel_pstate.rst10
1 files changed, 9 insertions, 1 deletions
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.