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The current behavior of the Step-wise thermal governor is to increase the cooling level one step at a time after trip point threshold passing by thermal zone temperature until the temperature stops to rise. Then, nothing is done until the temperature decreases below the (possibly updated) trip point threshold, at which point the cooling level is reduced straight to the applicable minimum. While this generally works, it is not in agreement with the throttling logic description comment in step_wise_manage() any more after some relatively recent changes, and in the case of passive cooling, it may lead to undesirable performance oscillations between high and low levels. For this reason, modify the governor's cooling device state selection function, get_target_state(), to reduce cooling by one level even if the temperature is still above the thermal zone threshold, but the temperature has started to fall down. However, ensure that the cooling level will remain above the applicable minimum in that case to pull the zone temperature further down, possibly until it falls below the trip threshold (which may now be equal to the low temperature of the trip). Doing so should help higher performance to be restored earlier in some cases which is desirable especially for passive trip points with relatively high hysteresis values. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com> Link: https://patch.msgid.link/1947735.tdWV9SEqCh@rafael.j.wysocki [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.