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Since it's likely to be useful for performance work with SVE let's have a pidbench that gives us some numbers for consideration. In order to ensure that we test exactly the scenario we want this is written in assembly - if system libraries use SVE this would stop us exercising the case where the process has never used SVE. We exercise three cases: - Never having used SVE. - Having used SVE once. - Using SVE after each syscall. by spinning running getpid() for a fixed number of iterations with the time measured using CNTVCT_EL0 reported on the console. This is obviously a totally unrealistic benchmark which will show the extremes of any performance variation but equally given the potential gotchas with use of FP instructions by system libraries it's good to have some concrete code shared to make it easier to compare notes on results. Testing over multiple SVE vector lengths will need to be done with vlset currently, the test could be extended to iterate over all of them if desired. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211202165107.1075259-1-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.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 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.