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66611c0475
The function graph infrastructure is now generic so that kretprobes, fprobes and BPF can use it. But there is still some leftover logic that only the function graph tracer itself uses. This is the calculation of the calltime and return time of the functions. The calculation of the calltime has been moved into the function graph tracer and those users that need it so that it doesn't cause overhead to the other users. But the return function timestamp was still called. Instead of just moving the taking of the timestamp into the function graph trace remove the calltime and rettime completely from the ftrace_graph_ret structure. Instead, move it into the function graph return entry event structure and this also moves all the calltime and rettime logic out of the generic fgraph.c code and into the tracing code that uses it. This has been reported to decrease the overhead by ~27%. Link: https://lore.kernel.org/all/Z3aSuql3fnXMVMoM@krava/ Link: https://lore.kernel.org/all/173665959558.1629214.16724136597211810729.stgit@devnote2/ Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20250121194436.15bdf71a@gandalf.local.home Reported-by: Jiri Olsa <olsajiri@gmail.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.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.