From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: [PATCH 47/91] perf intel-pt: Update documentation about using /proc/kcore Date: Wed, 6 May 2020 12:21:50 -0300 Message-ID: <20200506152234.21977-48-acme@kernel.org> References: <20200506152234.21977-1-acme@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200506152234.21977-1-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar , Thomas Gleixner Cc: Jiri Olsa , Namhyung Kim , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Adrian Hunter , Andi Kleen , Jiri Olsa , Arnaldo Carvalho de Melo List-Id: linux-perf-users.vger.kernel.org From: Adrian Hunter Update documentation to reflect the advent of the --kcore option for 'perf record'. Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Jiri Olsa Link: http://lore.kernel.org/lkml/20200429150751.12570-10-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- 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. -- 2.21.1