[PATCH 18/19] perf tools: Limit the ordered events queue by default to 100MB

[Jiri Olsa <jolsa@kernel.org>]

It's still configurable by report.queue-size config option,
but looks like 100MB limit is more sane than no limit at all.

There's some speedup for report on huge data files:

With the limit of 100 MB, I've got around 15% speedup on reporting
of ~10GB perf.data file.

  current code:
   621,685,704,665      cycles                    ( +-  0.52% )
   873,397,467,969      instructions              ( +-  0.00% )

     286.133268732 seconds time elapsed           ( +-  1.13% )

  with patches:
   603,933,987,185      cycles                    ( +-  0.45% )
   869,139,445,070      instructions              ( +-  0.00% )

     245.337510637 seconds time elapsed           ( +-  0.49% )

The speed up seems to be mainly in less cycles spent in servicing
page faults.

  current code:
     4.44%     0.01%  perf.old  [kernel.kallsyms]   [k] page_fault

  with patches:
     1.45%     0.00%      perf  [kernel.kallsyms]   [k] page_fault

  current code (faults event):
         6,643,807      faults                    ( +-  0.36% )

  with patches (faults event):
         2,214,756      faults                    ( +-  3.03% )

Also there's lower memory consuption.

Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/util/ordered-events.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index 1a699fc16b92..d7ee387cad51 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -243,7 +243,8 @@ void ordered_events_init(struct ordered_events *oe)
 	INIT_LIST_HEAD(&oe->events);
 	INIT_LIST_HEAD(&oe->cache);
 	INIT_LIST_HEAD(&oe->to_free);
-	oe->max_alloc_size = (u64) -1;
+	/* 100MB limitation by default */
+	oe->max_alloc_size = 100 * 1024 * 1024;
 	oe->cur_alloc_size = 0;
 }
 
-- 
1.8.3.1