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@hp.com>
Acked-by: David 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: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 17 insertions, 5 deletions

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index fa68a36bc461..81addcabb356 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",