From: kan.liang@linux.intel.com
To: peterz@infradead.org, acme@kernel.org, mingo@kernel.org,
linux-kernel@vger.kernel.org
Cc: jolsa@kernel.org, namhyung@kernel.org, ak@linux.intel.com,
vitaly.slobodskoy@intel.com, pavel.gerasimov@intel.com,
Kan Liang <kan.liang@linux.intel.com>
Subject: [PATCH 08/10] perf script: Add option to enable the LBR stitching approach
Date: Mon, 7 Oct 2019 10:59:08 -0700 [thread overview]
Message-ID: <20191007175910.2805-9-kan.liang@linux.intel.com> (raw)
In-Reply-To: <20191007175910.2805-1-kan.liang@linux.intel.com>
From: Kan Liang <kan.liang@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.
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
tools/perf/Documentation/perf-script.txt | 11 +++++++++++
tools/perf/builtin-script.c | 6 ++++++
2 files changed, 17 insertions(+)
diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 2599b057e47b..472f20f1e479 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -426,6 +426,17 @@ include::itrace.txt[]
--show-on-off-events::
Show the --switch-on/off events too.
+--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.
+
SEE ALSO
--------
linkperf:perf-record[1], linkperf:perf-script-perl[1],
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 67be8d31afab..0fc4d07864d1 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1641,6 +1641,7 @@ struct perf_script {
bool show_bpf_events;
bool allocated;
bool per_event_dump;
+ bool stitch_lbr;
struct evswitch evswitch;
struct perf_cpu_map *cpus;
struct perf_thread_map *threads;
@@ -1867,6 +1868,9 @@ static void process_event(struct perf_script *script,
if (PRINT_FIELD(IP)) {
struct callchain_cursor *cursor = NULL;
+ if (script->stitch_lbr)
+ al->thread->lbr_stitch_enable = true;
+
if (symbol_conf.use_callchain && sample->callchain &&
thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
sample, NULL, NULL, scripting_max_stack) == 0)
@@ -3556,6 +3560,8 @@ int cmd_script(int argc, const char **argv)
"file", "file saving guest os /proc/kallsyms"),
OPT_STRING(0, "guestmodules", &symbol_conf.default_guest_modules,
"file", "file saving guest os /proc/modules"),
+ OPT_BOOLEAN('\0', "stitch-lbr", &script.stitch_lbr,
+ "Enable LBR callgraph stitching approach"),
OPTS_EVSWITCH(&script.evswitch),
OPT_END()
};
--
2.17.1
next prev parent reply other threads:[~2019-10-07 18:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 17:59 [PATCH 00/10] Stitch LBR call stack kan.liang
2019-10-07 17:59 ` [PATCH 01/10] perf/core, x86: Add PERF_SAMPLE_LBR_TOS kan.liang
2019-10-08 8:31 ` Peter Zijlstra
2019-10-08 13:53 ` Liang, Kan
2019-10-08 14:38 ` Peter Zijlstra
2019-10-08 15:25 ` Liang, Kan
2019-10-08 16:32 ` Peter Zijlstra
2019-10-07 17:59 ` [PATCH 02/10] perf tools: Support PERF_SAMPLE_LBR_TOS kan.liang
2019-10-07 17:59 ` [PATCH 03/10] perf pmu: Add support for PMU capabilities kan.liang
2019-10-07 17:59 ` [PATCH 04/10] perf header: Support CPU " kan.liang
2019-10-07 17:59 ` [PATCH 05/10] perf machine: Refine the function for LBR call stack reconstruction kan.liang
2019-10-07 17:59 ` [PATCH 06/10] perf tools: Stitch LBR call stack kan.liang
2019-10-07 17:59 ` [PATCH 07/10] perf report: Add option to enable the LBR stitching approach kan.liang
2019-10-07 17:59 ` kan.liang [this message]
2019-10-07 17:59 ` [PATCH 09/10] perf top: " kan.liang
2019-10-07 17:59 ` [PATCH 10/10] perf c2c: " kan.liang
2019-10-07 18:24 ` [PATCH 00/10] Stitch LBR call stack Ingo Molnar
2019-10-07 20:06 ` Liang, Kan
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