tree b5ba45afb69212794a1fe53f215992413923e348
parent f0fe3cd7e12d8290c82284b5c8aee723cbd0371a
author Dirk Brandewie <dirk.j.brandewie@intel.com> 1401381144 -0700
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1401705905 +0200

intel_pstate: add sample time scaling

The PID assumes that samples are of equal time, which for a deferable
timers this is not true when the system goes idle.  This causes the
PID to take a long time to converge to the min P state and depending
on the pattern of the idle load can make the P state appear stuck.

The hold-off value of three sample times before using the scaling is
to give a grace period for applications that have high performance
requirements and spend a lot of time idle,  The poster child for this
behavior is the ffmpeg benchmark in the Phoronix test suite.

Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>