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Marc has reported that commit85975daeaa("cpuidle: menu: Avoid discarding useful information") caused the number of wakeup interrupts to increase on an idle system [1], which was not expected to happen after merely allowing shallower idle states to be selected by the governor in some cases. However, on the system in question, all of the idle states deeper than WFI are rejected by the driver due to a firmware issue [2]. This causes the governor to only consider the recent interval duriation data corresponding to attempts to enter WFI that are successful and the recent invervals table is filled with values lower than the scheduler tick period. Consequently, the governor predicts an idle duration below the scheduler tick period length and avoids stopping the tick more often which leads to the observed symptom. Address it by modifying the governor to update the recent intervals table also when entering the previously selected idle state fails, so it knows that the short idle intervals might have been the minority had the selected idle states been actually entered every time. Fixes:85975daeaa("cpuidle: menu: Avoid discarding useful information") Link: https://lore.kernel.org/linux-pm/86o6sv6n94.wl-maz@kernel.org/ [1] Link: https://lore.kernel.org/linux-pm/7ffcb716-9a1b-48c2-aaa4-469d0df7c792@arm.com/ [2] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Christian Loehle <christian.loehle@arm.com> Tested-by: Marc Zyngier <maz@kernel.org> Reviewed-by: Christian Loehle <christian.loehle@arm.com> Link: https://patch.msgid.link/2793874.mvXUDI8C0e@rafael.j.wysocki
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.