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Whenever there's audit context, __audit_inode_child() gets called numerous times, which can lead to high latency in scenarios that create too many sysfs/debugfs entries at once, for instance, upon device_add_disk() invocation. # uname -r 6.18.0-rc2+ # auditctl -a always,exit -F path=/tmp -k foo # time insmod loop max_loop=1000 real 0m46.676s user 0m0.000s sys 0m46.405s # perf record -a insmod loop max_loop=1000 # perf report --stdio |grep __audit_inode_child 32.73% insmod [kernel.kallsyms] [k] __audit_inode_child __audit_inode_child() searches for both the parent and the child in two different loops that iterate over the same list. This process can be optimized by merging these into a single loop, without changing the function behavior or affecting the code's readability. This patch merges the two loops that walk through the list context->names_list into a single loop. This optimization resulted in around 51% performance enhancement for the benchmark. # uname -r 6.18.0-rc2-enhancedv3+ # auditctl -a always,exit -F path=/tmp -k foo # time insmod loop max_loop=1000 real 0m22.899s user 0m0.001s sys 0m22.652s Signed-off-by: Ricardo Robaina <rrobaina@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.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 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.