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f4d99bdfd1
Skip end-of-sequence and non-statement lines while walking through lines
list.
The "end-of-sequence" line information means:
"the current address is that of the first byte after the
end of a sequence of target machine instructions."
(DWARF version 4 spec 6.2.2)
This actually means out of scope and we can not probe on it.
On the other hand, the statement lines (is_stmt) means:
"the current instruction is a recommended breakpoint location.
A recommended breakpoint location is intended to “represent”
a line, a statement and/or a semantically distinct subpart
of a statement."
(DWARF version 4 spec 6.2.2)
So, non-statement line info also should be skipped.
These can reduce unneeded probe points and also avoid an error.
E.g. without this patch:
# perf probe -a "clear_tasks_mm_cpumask:1"
Added new events:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_2 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_3 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_4 (on clear_tasks_mm_cpumask:1)
You can now use it in all perf tools, such as:
perf record -e probe:clear_tasks_mm_cpumask_4 -aR sleep 1
#
This puts 5 probes on one line, but acutally it's not inlined function.
This is because there are many non statement instructions at the
function prologue.
With this patch:
# perf probe -a "clear_tasks_mm_cpumask:1"
Added new event:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
You can now use it in all perf tools, such as:
perf record -e probe:clear_tasks_mm_cpumask -aR sleep 1
#
Now perf-probe skips unneeded addresses.
Committer testing:
Slightly different results, but similar:
Before:
# uname -a
Linux quaco 5.3.8-200.fc30.x86_64 #1 SMP Tue Oct 29 14:46:22 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
#
# perf probe -a "clear_tasks_mm_cpumask:1"
Added new events:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_2 (on clear_tasks_mm_cpumask:1)
You can now use it in all perf tools, such as:
perf record -e probe:clear_tasks_mm_cpumask_2 -aR sleep 1
#
After:
# perf probe -a "clear_tasks_mm_cpumask:1"
Added new event:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
You can now use it in all perf tools, such as:
perf record -e probe:clear_tasks_mm_cpumask -aR sleep 1
# perf probe -l
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@kernel/cpu.c)
#
Fixes:
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||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.