Commit 6dd912cb authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
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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: default avatarAdrian 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 43358d9d

tools/perf/Documentation/perf-intel-pt.txt

+9 −9
Original line number Diff line number Diff line
@@ -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.