lkml.org 
[lkml]   [2020]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 9/9] perf intel-pt: Update documentation about using /proc/kcore
Date
Update documentation to reflect the advent of the --kcore option for
'perf record'.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/Documentation/perf-intel-pt.txt | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 782eb8a65caf..eb8b7d42591a 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -69,22 +69,22 @@ And profiled with 'perf report' e.g.
To also trace kernel space presents a problem, namely kernel self-modifying
code. A fairly good kernel image is available in /proc/kcore but to get an
accurate image a copy of /proc/kcore needs to be made under the same conditions
-as the data capture. A script perf-with-kcore can do that, but beware that the
-script makes use of 'sudo' to copy /proc/kcore. If you have perf installed
-locally from the source tree you can do:
+as the data capture. 'perf record' can make a copy of /proc/kcore if the option
+--kcore is used, but access to /proc/kcore is restricted e.g.

- ~/libexec/perf-core/perf-with-kcore record pt_ls -e intel_pt// -- ls
+ sudo perf record -o pt_ls --kcore -e intel_pt// -- ls

-which will create a directory named 'pt_ls' and put the perf.data file and
-copies of /proc/kcore, /proc/kallsyms and /proc/modules into it. Then to use
-'perf report' becomes:
+which will create a directory named 'pt_ls' and put the perf.data file (named
+simply 'data') and copies of /proc/kcore, /proc/kallsyms and /proc/modules into
+it. The other tools understand the directory format, so to use 'perf report'
+becomes:

- ~/libexec/perf-core/perf-with-kcore report pt_ls
+ sudo perf report -i pt_ls

Because samples are synthesized after-the-fact, the sampling period can be
selected for reporting. e.g. sample every microsecond

- ~/libexec/perf-core/perf-with-kcore report pt_ls --itrace=i1usge
+ sudo perf report pt_ls --itrace=i1usge

See the sections below for more information about the --itrace option.

--
2.17.1
\
 
 \ /
  Last update: 2020-04-29 17:09    [W:0.554 / U:0.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site