Thomas Gleixner
f3eca381bd
Reading the current CPU frequency from /sys/..../scaling_cur_freq involves in the worst case two IPIs due to the ad hoc sampling. The frequency invariance infrastructure provides the APERF/MPERF samples already. Utilize them and consolidate this with the /proc/cpuinfo readout. The sample is considered valid for 20ms. So for idle or isolated NOHZ full CPUs the function returns 0, which is matching the previous behaviour. The resulting text size vs. the original APERF/MPERF plus the separate frequency invariance code: text: 2411 -> 723 init.text: 0 -> 767 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/r/20220415161206.934040006@linutronix.de
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 Restructured Text 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.