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f5ce815f34
Change tcmu to support DATA_BLOCK_SIZE being a multiple of PAGE_SIZE. There
are two reasons why one would like to have a bigger DATA_BLOCK_SIZE:
1) If userspace - e.g. due to data compression, encryption or
deduplication - needs to have receive or transmit data in a consecutive
buffer, we can define DATA_BLOCK_SIZE to the maximum size of a SCSI
READ/WRITE to enforce that userspace sees just one consecutive
buffer. That way we can avoid the need for doing data copy in
userspace.
2) Using a bigger data block size can speed up command processing in
tcmu. The number of free data blocks to look up in bitmap is reduced
substantially. The lookup for data pages in radix_tree can be done more
efficiently if there are multiple pages in a data block. The maximum
number of IOVs to set up is lower so cmd entries in the ring become
smaller.
Link: https://lore.kernel.org/r/20210324195758.2021-4-bostroesser@gmail.com
Signed-off-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.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.