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.
Filipe Manana
authored
The tree modification log functions are called very frequently, basically they are called every time a btree is modified (a pointer added or removed to a node, a new root for a btree is set, etc). Because of that, to avoid heavy lock contention on the lock that protects the list of tree mod log users, we have checks that test the emptiness of the list with a full memory barrier before the checks, so that when there are no tree mod log users we avoid taking the lock. Replace the memory barrier and list emptiness check with a test for a new bit set at fs_info->flags. This bit is used to indicate when there are tree mod log users, set whenever a user is added to the list and cleared when the last user is removed from the list. This makes the intention a bit more obvious and possibly more efficient (assuming test_bit() may be cheaper than a full memory barrier on some architectures). Signed-off-by:Filipe Manana <fdmanana@suse.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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