From 53651b28cfb637ef604abc189d877948d1af39bb Mon Sep 17 00:00:00 2001
From: yuzhoujian <yuzhoujian@didichuxing.com>
Date: Thu, 30 May 2019 14:29:22 +0100
Subject: perf record: Add support to collect callchains from kernel or user
 space only

One can just record callchains in the kernel or user space with this new
options.

We can use it together with "--all-kernel" options.

This two options is used just like print_stack(sys) or print_ustack(usr)
for systemtap.

Shown below is the usage of this new option combined with "--all-kernel"
options:

1. Configure all used events to run in kernel space and just collect
   kernel callchains.

  $ perf record -a -g --all-kernel --kernel-callchains

2. Configure all used events to run in kernel space and just collect
   user callchains.

  $ perf record -a -g --all-kernel --user-callchains

Committer notes:

Improved documentation to state that asking for kernel callchains really
is asking for excluding user callchains, and vice versa.

Further mentioned that using both won't get both, but nothing, as both
will be excluded.

Signed-off-by: yuzhoujian <yuzhoujian@didichuxing.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1559222962-22891-1-git-send-email-ufo19890607@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Documentation/perf-record.txt | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'tools/perf/Documentation/perf-record.txt')

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index de269430720a..15e0fa87241b 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -490,6 +490,17 @@ Configure all used events to run in kernel space.
 --all-user::
 Configure all used events to run in user space.
 
+--kernel-callchains::
+Collect callchains only from kernel space. I.e. this option sets
+perf_event_attr.exclude_callchain_user to 1.
+
+--user-callchains::
+Collect callchains only from user space. I.e. this option sets
+perf_event_attr.exclude_callchain_kernel to 1.
+
+Don't use both --kernel-callchains and --user-callchains at the same time or no
+callchains will be collected.
+
 --timestamp-filename
 Append timestamp to output file name.
 
-- 
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