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036f463fe1
The xattr scrubber functions use the temporary memory buffer either for storing bitmaps or for testing if attribute value extraction works. The bitmap code always zeroes what it needs and the value extraction sets the buffer contents, so it's not necessary to waste CPU time zeroing on allocation. Note that while we never read the contents that the attr value extraction function sets, we do need to call it to check the remote attribute header and CRCs to check for corruption. A flame graph analysis showed that we were spending 7% of a xfs_scrub run (the whole program, not just the attr scrubber itself) allocating and zeroing 64k segments needlessly. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.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.