From 6dd912cbadb9f9746a525c74f09c0e36cee13ee2 Mon Sep 17 00:00:00 2001 From: Adrian Hunter <adrian.hunter@intel.com> Date: Wed, 29 Apr 2020 18:07:51 +0300 Subject: [PATCH] perf intel-pt: Update documentation about using /proc/kcore Update documentation to reflect the advent of the --kcore option for 'perf record'. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lore.kernel.org/lkml/20200429150751.12570-10-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 782eb8a65caf0d..eb8b7d42591a63 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. -- GitLab