From: Kan Liang <kan.li...@linux.intel.com>
With the LBR stitching approach, the reconstructed LBR call stack
can break the HW limitation. However, it may reconstruct invalid call
stacks in some cases, e.g. exception handing such as setjmp/longjmp.
Also, it may impact the processing time especially when the number of
samples with stitched LBRs are huge.
Add an option to enable the approach.
# To display the perf.data header info, please use
# --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6K of event 'cycles'
# Event count (approx.): 6492797701
#
# Children Self Command Shared Object Symbol
# ........ ........ ............... ..................
# .................................
#
99.99% 99.99% tchain_edit tchain_edit [.] f43
|
---main
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--99.65%--f32
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Reviewed-by: Andi Kleen <a...@linux.intel.com>
Signed-off-by: Kan Liang <kan.li...@linux.intel.com>
---
tools/perf/Documentation/perf-report.txt | 11 +++++++++++
tools/perf/builtin-report.c | 6 ++++++
2 files changed, 17 insertions(+)
diff --git a/tools/perf/Documentation/perf-report.txt
b/tools/perf/Documentation/perf-report.txt
index 7315f155803f..c0651b68ed5d 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -476,6 +476,17 @@ include::itrace.txt[]
This option extends the perf report to show reference callgraphs,
which collected by reference event, in no callgraph event.
+--stitch-lbr::
+ Show callgraph with stitched LBRs, which may have more complete
+ callgraph. The perf.data file must have been obtained using
+ perf record --call-graph lbr.
+ Disabled by default. In common cases with call stack overflows,
+ it can recreate better call stacks than the default lbr call stack
+ output. But this approach is not full proof. There can be cases
+ where it creates incorrect call stacks from incorrect matches.
+ The known limitations include exception handing such as
+ setjmp/longjmp will have calls/returns not match.
+
--socket-filter::
Only report the samples on the processor socket that match with this
filter
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index aae0e57c60fb..0d4275a46645 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -83,6 +83,7 @@ struct report {
bool header_only;
bool nonany_branch_mode;
bool group_set;
+ bool stitch_lbr;
int max_stack;
struct perf_read_values show_threads_values;
struct annotation_options annotation_opts;
@@ -263,6 +264,9 @@ static int process_sample_event(struct perf_tool *tool,
return -1;
}
+ if (rep->stitch_lbr)
+ al.thread->lbr_stitch_enable = true;
+
if (symbol_conf.hide_unresolved && al.sym == NULL)
goto out_put;
@@ -1183,6 +1187,8 @@ int cmd_report(int argc, const char **argv)
"Show full source file name path for source lines"),
OPT_BOOLEAN(0, "show-ref-call-graph", &symbol_conf.show_ref_callgraph,
"Show callgraph from reference event"),
+ OPT_BOOLEAN(0, "stitch-lbr", &report.stitch_lbr,
+ "Enable LBR callgraph stitching approach"),
OPT_INTEGER(0, "socket-filter", &report.socket_filter,
"only show processor socket that match with this filter"),
OPT_BOOLEAN(0, "raw-trace", &symbol_conf.raw_trace,
--
2.17.1
