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The delta index is a space and memory efficient alternative to a hashtable. Instead of storing the entire key for each entry, the entries are sorted by key and only the difference between adjacent keys (the delta) is stored. If the keys are evenly distributed, the size of the deltas follows an exponential distribution, and the deltas can use a Huffman code to take up even less space. This structure allows the index to use many fewer bytes per entry than a traditional hash table, but it is slightly more expensive to look up entries, because a request must read and sum every entry in a list of deltas in order to find a given record. The delta index reduces this lookup cost by splitting its key space into many sub-lists, each starting at a fixed key value, so that each individual list is short. Co-developed-by: J. corwin Coburn <corwin@hurlbutnet.net> Signed-off-by: J. corwin Coburn <corwin@hurlbutnet.net> Co-developed-by: Michael Sclafani <dm-devel@lists.linux.dev> Signed-off-by: Michael Sclafani <dm-devel@lists.linux.dev> Co-developed-by: Thomas Jaskiewicz <tom@jaskiewicz.us> Signed-off-by: Thomas Jaskiewicz <tom@jaskiewicz.us> Signed-off-by: Matthew Sakai <msakai@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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.