Rafael J. Wysocki
0cbef962ce
According to [1], the handling of device suspend and resume, and particularly the latter, involves unnecessary overhead related to starting new async work items for devices that cannot make progress right away because they have to wait for other devices. To reduce this problem in the resume path, use the observation that starting the async resume of the children of a device after resuming the parent is likely to produce less scheduling and memory management noise than starting it upfront while at the same time it should not increase the resume duration substantially. Accordingly, modify the code to start the async resume of the device's children when the processing of the parent has been completed in each stage of device resume and only start async resume upfront for devices without parents. Also make it check if a given device can be resumed asynchronously before starting the synchronous resume of it in case it will have to wait for another that is already resuming asynchronously. In addition to making the async resume of devices more friendly to systems with relatively less computing resources, this change is also preliminary for analogous changes in the suspend path. On the systems where it has been tested, this change by itself does not affect the overall system resume duration in a measurable way. Link: https://lore.kernel.org/linux-pm/20241114220921.2529905-1-saravanak@google.com/ [1] Suggested-by: Saravana Kannan <saravanak@google.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://patch.msgid.link/22630663.EfDdHjke4D@rjwysocki.net
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.