The following commit has been merged into the perf/core branch of tip: Commit-ID: 771fd155dfaa5332da69d606db16fe27bd9d388d Gitweb: https://git.kernel.org/tip/771fd155dfaa5332da69d606db16fe27bd9d388d Author: Kan Liang <kan.liang@xxxxxxxxxxxxxxx> AuthorDate: Thu, 19 Mar 2020 13:25:09 -07:00 Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> CommitterDate: Sat, 18 Apr 2020 09:05:01 -03:00 perf thread: Add a knob for LBR stitch approach The LBR stitch approach should be disabled by default. Because - The stitching approach base on LBR call stack technology. The known limitations of LBR call stack technology still apply to the approach, e.g. Exception handing such as setjmp/longjmp will have calls/returns not match. - This approach is not foolproof. There can be cases where it creates incorrect call stacks from incorrect matches. There is no attempt to validate any matches in another way. The 'lbr_stitch_enable' is used to indicate whether enable LBR stitch approach, which is disabled by default. The following patch will introduce a new option for each tools to enable the LBR stitch approach. Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx> Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx> Cc: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx> Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: Pavel Gerasimov <pavel.gerasimov@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Vitaly Slobodskoy <vitaly.slobodskoy@xxxxxxxxx> Link: http://lore.kernel.org/lkml/20200319202517.23423-10-kan.liang@xxxxxxxxxxxxxxx Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> --- tools/perf/util/thread.c | 1 + tools/perf/util/thread.h | 3 +++ 2 files changed, 4 insertions(+) diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c index 28b7193..1f080db 100644 --- a/tools/perf/util/thread.c +++ b/tools/perf/util/thread.c @@ -47,6 +47,7 @@ struct thread *thread__new(pid_t pid, pid_t tid) thread->tid = tid; thread->ppid = -1; thread->cpu = -1; + thread->lbr_stitch_enable = false; INIT_LIST_HEAD(&thread->namespaces_list); INIT_LIST_HEAD(&thread->comm_list); init_rwsem(&thread->namespaces_lock); diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h index 20b96b5..9529405 100644 --- a/tools/perf/util/thread.h +++ b/tools/perf/util/thread.h @@ -46,6 +46,9 @@ struct thread { struct srccode_state srccode_state; bool filter; int filter_entry_depth; + + /* LBR call stack stitch */ + bool lbr_stitch_enable; }; struct machine;
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