c7876a0cc6
Patch series "selftests/mm: mremap_test: Optimizations and style fixes". The mremap_test, in a worst case controlled by the -t flag, does a for loop iteration in orders of GB. Without compromising on the stdout report, the aim is to reduce this time. A pre-filled random buffer is allocated based on the seed, replacing repetitive rand() calls. The byte pattern in the memory locations is set through memcpy() from the random buffer. Replacing the loop for printing the mismatch index to stdout, employ an efficient algorithm by breaking the comparison into chunks, use the highly optimized memcmp() library function, and when a mismatch does occur, only then do a brute force iteration. Also, use sscanf() to parse /proc/self/maps for consistency across files. Execution time results (x86 system): ./mremap_test Original: 3 seconds After change: 0.8 seconds ./mremap_test -t100 Original: 17 seconds After change: 2 seconds ./mremap_test -t0 (worst case): Original: 9:40 minutes After change: 45 seconds This patch (of 3): Allocate a pre-filled random buffer using the seed. Replace iterative copying of the random sequence to buffers using the highly optimized library function memcpy(). Link: https://lkml.kernel.org/r/20240330173557.2697684-1-dev.jain@arm.com Link: https://lkml.kernel.org/r/20240330173557.2697684-2-dev.jain@arm.com Signed-off-by: Dev Jain <dev.jain@arm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.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 reStructuredText 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.