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0cae23b66a
When deleting items from a leaf, we always compute the sum of the data sizes of the items that are going to be deleted. However we only use that sum when the last item to delete is behind the last item in the leaf. This unnecessarily wastes CPU time when we are deleting either the whole leaf or from some slot > 0 up to the last item in the leaf, and both of these cases are common (e.g. truncation operation, either as a result of truncate(2) or when logging inodes, deleting checksums after removing a large enough extent, etc). So compute only the sum of the data sizes if the last item to be deleted does not match the last item in the leaf. This change if part of a patchset that is comprised of the following patches: 1/6 btrfs: remove unnecessary leaf free space checks when pushing items 2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf 3/6 btrfs: avoid unnecessary computation when deleting items from a leaf 4/6 btrfs: remove constraint on number of visited leaves when replacing extents 5/6 btrfs: remove useless path release in the fast fsync path 6/6 btrfs: prepare extents to be logged before locking a log tree path The last patch in the series has some performance test result in its changelog. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.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.