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ec8c244205
This patch introduces new compacted compression indexes. In contract to legacy compression indexes that each 4k logical cluster has an 8-byte index, compacted ondisk compression indexes will have amortized 2 bytes for each 4k logical cluster (compacted 2B) amortized 4 bytes for each 4k logical cluster (compacted 4B) In detail, several continuous clusters will be encoded in a compacted pack with cluster types, offsets, and one blkaddr at the end of the pack to leave 4-byte margin for better decoding performance, as illustrated below: _____________________________________________ |___@_____ encoded bits __________|_ blkaddr _| 0 . amortized * vcnt . . . . amortized * vcnt - 4 . . .___________________. |_type_|_clusterofs_| Note that compacted 2 / 4B should be aligned with 32 / 8 bytes in order to avoid each pack crossing page boundary. Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.