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Settle on three "flavors" of uprobe/uretprobe, installed on different kinds of instruction: nop, push, and ret. All three are testing different internal code paths emulating or single-stepping instructions, so are interesting to compare and benchmark separately. To ensure `push rbp` instruction we ensure that uprobe_target_push() is not a leaf function by calling (global __weak) noop function and returning something afterwards (if we don't do that, compiler will just do a tail call optimization). Also, we need to make sure that compiler isn't skipping frame pointer generation, so let's add `-fno-omit-frame-pointers` to Makefile. Just to give an idea of where we currently stand in terms of relative performance of different uprobe/uretprobe cases vs a cheap syscall (getpgid()) baseline, here are results from my local machine: $ benchs/run_bench_uprobes.sh base : 1.561 ± 0.020M/s uprobe-nop : 0.947 ± 0.007M/s uprobe-push : 0.951 ± 0.004M/s uprobe-ret : 0.443 ± 0.007M/s uretprobe-nop : 0.471 ± 0.013M/s uretprobe-push : 0.483 ± 0.004M/s uretprobe-ret : 0.306 ± 0.007M/s Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240301214551.1686095-1-andrii@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.