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Hou Tao says: ==================== Hi, The motivation for introducing bpf_strncmp() helper comes from two aspects: (1) clang doesn't always replace strncmp() automatically In tracing program, sometimes we need to using a home-made strncmp() to check whether or not the file name is expected. (2) the performance of home-made strncmp is not so good As shown in the benchmark in patch #4, the performance of bpf_strncmp() helper is 18% or 33% better than home-made strncmp() under x86-64 or arm64 when the compared string length is 64. When the string length grows to 4095, the performance win will be 179% or 600% under x86-64 or arm64. Any comments are welcome. Regards, Tao Change Log: v2: * rebased on bpf-next * drop patch "selftests/bpf: factor out common helpers for benchmarks" (suggested by Andrii) * remove unnecessary inline functions and add comments for programs which will be rejected by verifier in patch 4 (suggested by Andrii) * rename variables used in will-fail programs to clarify the purposes. v1: https://lore.kernel.org/bpf/20211130142215.1237217-1-houtao1@huawei.com * change API to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) * add benchmark refactor and benchmark between bpf_strncmp() and strncmp() RFC: https://lore.kernel.org/bpf/20211106132822.1396621-1-houtao1@huawei.com/ ==================== Signed-off-by: Alexei Starovoitov <ast@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.