[tip:perf/core] perf report: Add --max-stack option to limit callchain stack scan
From: tip-bot for Waiman Long
Date: Wed Oct 23 2013 - 03:56:56 EST
Commit-ID: 91e95617429cb272fd908b1928a1915b37b9655f
Gitweb: http://git.kernel.org/tip/91e95617429cb272fd908b1928a1915b37b9655f
Author: Waiman Long <Waiman.Long@xxxxxx>
AuthorDate: Fri, 18 Oct 2013 10:38:48 -0400
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 21 Oct 2013 17:36:25 -0300
perf report: Add --max-stack option to limit callchain stack scan
When callgraph data was included in the perf data file, it may take a
long time to scan all those data and merge them together especially if
the stored callchains are long and the perf data file itself is large,
like a Gbyte or so.
The callchain stack is currently limited to PERF_MAX_STACK_DEPTH (127).
This is a large value. Usually the callgraph data that developers are
most interested in are the first few levels, the rests are usually not
looked at.
This patch adds a new --max-stack option to perf-report to limit the
depth of callchain stack data to look at to reduce the time it takes for
perf-report to finish its processing. It trades the presence of trailing
stack information with faster speed.
The following table shows the elapsed time of doing perf-report on a
perf.data file of size 985,531,828 bytes.
--max_stack Elapsed Time Output data size
----------- ------------ ----------------
not set 88.0s 124,422,651
64 87.5s 116,303,213
32 87.2s 112,023,804
16 86.6s 94,326,380
8 59.9s 33,697,248
4 40.7s 10,116,637
-g none 27.1s 2,555,810
Signed-off-by: Waiman Long <Waiman.Long@xxxxxx>
Acked-by: David Ahern <dsahern@xxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Aswin Chandramouleeswaran <aswin@xxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Scott J Norton <scott.norton@xxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1382107129-2010-4-git-send-email-Waiman.Long@xxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/Documentation/perf-report.txt | 8 ++++++++
tools/perf/builtin-report.c | 22 +++++++++++++++++-----
tools/perf/builtin-top.c | 3 ++-
tools/perf/util/machine.c | 14 +++++++++-----
tools/perf/util/machine.h | 3 ++-
tools/perf/util/session.c | 3 ++-
6 files changed, 40 insertions(+), 13 deletions(-)
diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index be5ad87..10a2798 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -141,6 +141,14 @@ OPTIONS
Default: fractal,0.5,callee,function.
+--max-stack::
+ Set the stack depth limit when parsing the callchain, anything
+ beyond the specified depth will be ignored. This is a trade-off
+ between information loss and faster processing especially for
+ workloads that can have a very long callchain stack.
+
+ Default: 127
+
-G::
--inverted::
alias for inverted caller based call graph.
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index fa68a36..81addca 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -49,6 +49,7 @@ struct perf_report {
bool show_threads;
bool inverted_callchain;
bool mem_mode;
+ int max_stack;
struct perf_read_values show_threads_values;
const char *pretty_printing_style;
const char *cpu_list;
@@ -90,7 +91,8 @@ static int perf_report__add_mem_hist_entry(struct perf_tool *tool,
if ((sort__has_parent || symbol_conf.use_callchain) &&
sample->callchain) {
err = machine__resolve_callchain(machine, evsel, al->thread,
- sample, &parent, al);
+ sample, &parent, al,
+ rep->max_stack);
if (err)
return err;
}
@@ -181,7 +183,8 @@ static int perf_report__add_branch_hist_entry(struct perf_tool *tool,
if ((sort__has_parent || symbol_conf.use_callchain)
&& sample->callchain) {
err = machine__resolve_callchain(machine, evsel, al->thread,
- sample, &parent, al);
+ sample, &parent, al,
+ rep->max_stack);
if (err)
return err;
}
@@ -244,18 +247,21 @@ out:
return err;
}
-static int perf_evsel__add_hist_entry(struct perf_evsel *evsel,
+static int perf_evsel__add_hist_entry(struct perf_tool *tool,
+ struct perf_evsel *evsel,
struct addr_location *al,
struct perf_sample *sample,
struct machine *machine)
{
+ struct perf_report *rep = container_of(tool, struct perf_report, tool);
struct symbol *parent = NULL;
int err = 0;
struct hist_entry *he;
if ((sort__has_parent || symbol_conf.use_callchain) && sample->callchain) {
err = machine__resolve_callchain(machine, evsel, al->thread,
- sample, &parent, al);
+ sample, &parent, al,
+ rep->max_stack);
if (err)
return err;
}
@@ -332,7 +338,8 @@ static int process_sample_event(struct perf_tool *tool,
if (al.map != NULL)
al.map->dso->hit = 1;
- ret = perf_evsel__add_hist_entry(evsel, &al, sample, machine);
+ ret = perf_evsel__add_hist_entry(tool, evsel, &al, sample,
+ machine);
if (ret < 0)
pr_debug("problem incrementing symbol period, skipping event\n");
}
@@ -772,6 +779,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
.ordered_samples = true,
.ordering_requires_timestamps = true,
},
+ .max_stack = PERF_MAX_STACK_DEPTH,
.pretty_printing_style = "normal",
};
const struct option options[] = {
@@ -812,6 +820,10 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
OPT_CALLBACK_DEFAULT('g', "call-graph", &report, "output_type,min_percent[,print_limit],call_order",
"Display callchains using output_type (graph, flat, fractal, or none) , min percent threshold, optional print limit, callchain order, key (function or address). "
"Default: fractal,0.5,callee,function", &parse_callchain_opt, callchain_default_opt),
+ OPT_INTEGER(0, "max-stack", &report.max_stack,
+ "Set the maximum stack depth when parsing the callchain, "
+ "anything beyond the specified depth will be ignored. "
+ "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
OPT_BOOLEAN('G', "inverted", &report.inverted_callchain,
"alias for inverted call graph"),
OPT_CALLBACK(0, "ignore-callees", NULL, "regex",
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d934f70..112cb7d 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -770,7 +770,8 @@ static void perf_event__process_sample(struct perf_tool *tool,
sample->callchain) {
err = machine__resolve_callchain(machine, evsel,
al.thread, sample,
- &parent, &al);
+ &parent, &al,
+ PERF_MAX_STACK_DEPTH);
if (err)
return;
}
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 6b861ae..ea93425 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1253,10 +1253,12 @@ static int machine__resolve_callchain_sample(struct machine *machine,
struct thread *thread,
struct ip_callchain *chain,
struct symbol **parent,
- struct addr_location *root_al)
+ struct addr_location *root_al,
+ int max_stack)
{
u8 cpumode = PERF_RECORD_MISC_USER;
- unsigned int i;
+ int chain_nr = min(max_stack, (int)chain->nr);
+ int i;
int err;
callchain_cursor_reset(&callchain_cursor);
@@ -1266,7 +1268,7 @@ static int machine__resolve_callchain_sample(struct machine *machine,
return 0;
}
- for (i = 0; i < chain->nr; i++) {
+ for (i = 0; i < chain_nr; i++) {
u64 ip;
struct addr_location al;
@@ -1338,12 +1340,14 @@ int machine__resolve_callchain(struct machine *machine,
struct thread *thread,
struct perf_sample *sample,
struct symbol **parent,
- struct addr_location *root_al)
+ struct addr_location *root_al,
+ int max_stack)
{
int ret;
ret = machine__resolve_callchain_sample(machine, thread,
- sample->callchain, parent, root_al);
+ sample->callchain, parent,
+ root_al, max_stack);
if (ret)
return ret;
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index d44c09b..4c1f5d5 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -92,7 +92,8 @@ int machine__resolve_callchain(struct machine *machine,
struct thread *thread,
struct perf_sample *sample,
struct symbol **parent,
- struct addr_location *root_al);
+ struct addr_location *root_al,
+ int max_stack);
/*
* Default guest kernel is defined by parameter --guestkallsyms
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 19fc716..854c5aa 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1512,7 +1512,8 @@ void perf_evsel__print_ip(struct perf_evsel *evsel, union perf_event *event,
if (symbol_conf.use_callchain && sample->callchain) {
if (machine__resolve_callchain(machine, evsel, al.thread,
- sample, NULL, NULL) != 0) {
+ sample, NULL, NULL,
+ PERF_MAX_STACK_DEPTH) != 0) {
if (verbose)
error("Failed to resolve callchain. Skipping\n");
return;
--
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