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Ard Biesheuvel 8769177658 ARM: vfp: Record VFP bounces as perf emulation faults
VFP 'bouncing' occurs when the VFP unit cannot complete the execution of
a VFP instruction, either because it is not implemented at all, or
because the values of the arguments are out of range for the hardware
implementation, and the software needs to step in to complete the
operation.

To give some insight in how much certain programs rely on this bouncing,
record the emulation of a VFP instruction in perf's emulation-faults
counter.

This can be used like so

  perf stat -e emulation-faults ./testfloat -all2

and the output will be something like

 Performance counter stats for './testfloat -all2':

           259,277      emulation-faults:u

       6.846432176 seconds time elapsed

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
History 2023-05-16 20:24:08 +02:00
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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.