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If the divisor is a constant use specific division functions to
avoid extra branches when the trigger is hit.
If the divisor constant but not a power of 2, the division can be
replaced with a multiplication and shift in the following case:
Let X = dividend and Y = divisor.
Choose Z = some power of 2. If Y <= Z, then:
X / Y = (X * (Z / Y)) / Z
(Z / Y) is a constant (mult) which is calculated at parse time, so:
X / Y = (X * mult) / Z
The division by Z can be replaced by a shift since Z is a power of 2:
X / Y = (X * mult) >> shift
As long, as X < Z the results will not be off by more than 1.
Link: https://lkml.kernel.org/r/20211029232410.3494196-1-kaleshsingh@google.com
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
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| usr | ||
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| .clang-format | ||
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| README | ||
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.