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The test_overhead bpf program is designed to compare performance between tracepoint and kprobe. Initially it used task_rename and urandom_read tracepoint. However, commit14c174633f("random: remove unused tracepoints") removed urandom_read tracepoint, and for this reason the test_overhead got broken. This commit introduces new microbenchmark using fib_table_lookup. This microbenchmark sends UDP packets to localhost in order to invoke fib_table_lookup. In a nutshell: fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); addr.sin_addr.s_addr = inet_addr(DUMMY_IP); addr.sin_port = htons(DUMMY_PORT); for() { sendto(fd, buf, strlen(buf), 0, (struct sockaddr *)&addr, sizeof(addr)); } on 4 cpus in parallel: lookup per sec base (no tracepoints, no kprobes) 381k with kprobe at fib_table_lookup() 325k with tracepoint at fib:fib_table_lookup 330k with raw_tracepoint at fib:fib_table_lookup 365k Fixes:14c174633f("random: remove unused tracepoints") Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Link: https://lore.kernel.org/r/20230115071613.125791-6-danieltimlee@gmail.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.