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Commit 91e95617 authored by Waiman Long's avatar Waiman Long Committed by Arnaldo Carvalho de Melo
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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: default avatarWaiman Long <Waiman.Long@hp.com>
Acked-by: default avatarDavid Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1382107129-2010-4-git-send-email-Waiman.Long@hp.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent cc9784bd

tools/perf/Documentation/perf-report.txt

+8 −0
Original line number Diff line number Diff line
@@ -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.

tools/perf/builtin-report.c

+17 −5
Original line number Diff line number Diff line
@@ -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 @@ static int perf_report__add_branch_hist_entry(struct perf_tool *tool, 
	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",

tools/perf/builtin-top.c

+2 −1
Original line number Diff line number Diff line
@@ -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;

		}

tools/perf/util/machine.c

+9 −5
Original line number Diff line number Diff line
@@ -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;

tools/perf/util/machine.h

+2 −1
Original line number Diff line number Diff line
@@ -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