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perf tools: Add documentation for BPF event selection

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Add documentation for how to pass a BPF program as a perf event.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190201134651.12373-1-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Changbin Du 2019-02-01 21:46:51 +08:00 committed by Arnaldo Carvalho de Melo
parent dbd2a1d57f
commit 55fa8b8c0a
2 changed files with 45 additions and 0 deletions
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31
tools/perf/Documentation/perf-config.txt
View File

@ -120,6 +120,10 @@ Given a $HOME/.perfconfig like this:
children = true
group = true
[llvm]
dump-obj = true
clang-opt = -g
You can hide source code of annotate feature setting the config to false with
% perf config annotate.hide_src_code=true
@ -553,6 +557,33 @@ trace.*::
trace.show_zeros::
Do not suppress syscall arguments that are equal to zero.
llvm.*::
llvm.clang-path::
Path to clang. If omit, search it from $PATH.
llvm.clang-bpf-cmd-template::
Cmdline template. Below lines show its default value. Environment
variable is used to pass options.
"$CLANG_EXEC -D__KERNEL__ $CLANG_OPTIONS $KERNEL_INC_OPTIONS \
-Wno-unused-value -Wno-pointer-sign -working-directory \
$WORKING_DIR -c $CLANG_SOURCE -target bpf -O2 -o -"
llvm.clang-opt::
Options passed to clang.
llvm.kbuild-dir::
kbuild directory. If not set, use /lib/modules/`uname -r`/build.
If set to "" deliberately, skip kernel header auto-detector.
llvm.kbuild-opts::
Options passed to 'make' when detecting kernel header options.
llvm.dump-obj::
Enable perf dump BPF object files compiled by LLVM.
llvm.opts::
Options passed to llc.
SEE ALSO
--------
linkperf:perf[1]

14
tools/perf/Documentation/perf-record.txt
View File

@ -88,6 +88,20 @@ OPTIONS
If you want to profile write accesses in [0x1000~1008), just set
'mem:0x1000/8:w'.
- a BPF source file (ending in .c) or a precompiled object file (ending
in .o) selects one or more BPF events.
The BPF program can attach to various perf events based on the ELF section
names.
When processing a '.c' file, perf searches an installed LLVM to compile it
into an object file first. Optional clang options can be passed via the
'--clang-opt' command line option, e.g.:
perf record --clang-opt "-DLINUX_VERSION_CODE=0x50000" \
-e tests/bpf-script-example.c
Note: '--clang-opt' must be placed before '--event/-e'.
- a group of events surrounded by a pair of brace ("{event1,event2,...}").
Each event is separated by commas and the group should be quoted to
prevent the shell interpretation. You also need to use --group on