[PATCH 1/3] benchtests: Add malloc microbenchmark

[Will Newton <will dot newton at linaro dot org>]

Add a microbenchmark for measuring malloc and free performance. The
benchmark allocates and frees buffers of random sizes in a random order
and measures the overall execution time and RSS.

The random block sizes used follow an inverse square distribution
which is intended to mimic the behaviour of real applications which
tend to allocate many more small blocks than large ones.

ChangeLog:

2014-10-03  Will Newton  <will.newton@linaro.org>

	* benchtests/Makefile (stdlib-bench): Add malloc benchmark.
	* benchtests/bench-malloc.c: New file.
---
 benchtests/Makefile       |   2 +-
 benchtests/bench-malloc.c | 219 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 220 insertions(+), 1 deletion(-)
 create mode 100644 benchtests/bench-malloc.c

diff --git a/benchtests/Makefile b/benchtests/Makefile
index fd3036d..1f8eb82 100644
--- a/benchtests/Makefile
+++ b/benchtests/Makefile
@@ -37,7 +37,7 @@ string-bench := bcopy bzero memccpy memchr memcmp memcpy memmem memmove \
 		strspn strstr strcpy_chk stpcpy_chk memrchr strsep strtok
 string-bench-all := $(string-bench)
 
-stdlib-bench := strtod
+stdlib-bench := strtod malloc
 
 benchset := $(string-bench-all) $(stdlib-bench)
 
diff --git a/benchtests/bench-malloc.c b/benchtests/bench-malloc.c
new file mode 100644
index 0000000..54631ed
--- /dev/null
+++ b/benchtests/bench-malloc.c
@@ -0,0 +1,219 @@
+/* Benchmark malloc and free functions.
+   Copyright (C) 2013-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <math.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+#include "bench-timing.h"
+#include "json-lib.h"
+
+/* Benchmark duration in seconds.  */
+#define BENCHMARK_DURATION	60
+#define RAND_SEED		88
+
+/* Maximum memory that can be allocated at any one time is:
+
+   WORKING_SET_SIZE * MAX_ALLOCATION_SIZE
+
+   However due to the distribution of the random block sizes
+   the typical amount allocated will be much smaller.  */
+#define WORKING_SET_SIZE	1024
+
+#define MIN_ALLOCATION_SIZE	4
+#define MAX_ALLOCATION_SIZE	32768
+
+/* Get a random block size with an inverse square distribution.  */
+static unsigned int
+get_block_size (unsigned int rand_data)
+{
+  /* Inverse square.  */
+  const float exponent = -2;
+  /* Minimum value of distribution.  */
+  const float dist_min = MIN_ALLOCATION_SIZE;
+  /* Maximum value of distribution.  */
+  const float dist_max = MAX_ALLOCATION_SIZE;
+
+  float min_pow = powf (dist_min, exponent + 1);
+  float max_pow = powf (dist_max, exponent + 1);
+
+  float r = (float) rand_data / RAND_MAX;
+
+  return (unsigned int) powf ((max_pow - min_pow) * r + min_pow, 1 / (exponent + 1));
+}
+
+#define NUM_BLOCK_SIZES	8000
+#define NUM_OFFSETS	((WORKING_SET_SIZE) * 4)
+
+static unsigned int random_block_sizes[NUM_BLOCK_SIZES];
+static unsigned int random_offsets[NUM_OFFSETS];
+
+static void
+init_random_values (void)
+{
+  for (size_t i = 0; i < NUM_BLOCK_SIZES; i++)
+    random_block_sizes[i] = get_block_size (rand ());
+
+  for (size_t i = 0; i < NUM_OFFSETS; i++)
+    random_offsets[i] = rand () % WORKING_SET_SIZE;
+}
+
+static unsigned int
+get_random_block_size (unsigned int *state)
+{
+  unsigned int idx = *state;
+
+  if (idx >= NUM_BLOCK_SIZES - 1)
+    idx = 0;
+  else
+    idx++;
+
+  *state = idx;
+
+  return random_block_sizes[idx];
+}
+
+static unsigned int
+get_random_offset (unsigned int *state)
+{
+  unsigned int idx = *state;
+
+  if (idx >= NUM_OFFSETS - 1)
+    idx = 0;
+  else
+    idx++;
+
+  *state = idx;
+
+  return random_offsets[idx];
+}
+
+static volatile bool timeout;
+
+static void alarm_handler (int signum)
+{
+  timeout = true;
+}
+
+/* Allocate and free blocks in a random order.  */
+static size_t
+malloc_benchmark_loop (void **ptr_arr)
+{
+  unsigned int offset_state = 0, block_state = 0;
+  size_t iters = 0;
+
+  while (!timeout)
+    {
+      unsigned int next_idx = get_random_offset (&offset_state);
+      unsigned int next_block = get_random_block_size (&block_state);
+
+      free (ptr_arr[next_idx]);
+
+      ptr_arr[next_idx] = malloc (next_block);
+
+      iters++;
+    }
+
+  return iters;
+}
+
+static timing_t
+do_benchmark (size_t *iters)
+{
+  timing_t elapsed, start, stop;
+  void *working_set[WORKING_SET_SIZE];
+
+  memset (working_set, 0, sizeof (working_set));
+
+  TIMING_NOW (start);
+  *iters = malloc_benchmark_loop (working_set);
+  TIMING_NOW (stop);
+
+  TIMING_DIFF (elapsed, start, stop);
+
+  return elapsed;
+}
+
+int
+main (int argc, char **argv)
+{
+  timing_t cur;
+  size_t iters = 0;
+  unsigned long res;
+  json_ctx_t json_ctx;
+  double d_total_s, d_total_i;
+  struct sigaction act;
+
+  init_random_values ();
+
+  json_init (&json_ctx, 0, stdout);
+
+  json_document_begin (&json_ctx);
+
+  json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
+
+  json_attr_object_begin (&json_ctx, "functions");
+
+  json_attr_object_begin (&json_ctx, "malloc");
+
+  json_attr_object_begin (&json_ctx, "");
+
+  TIMING_INIT (res);
+
+  (void) res;
+
+  memset (&act, 0, sizeof (act));
+  act.sa_handler = &alarm_handler;
+
+  sigaction (SIGALRM, &act, NULL);
+
+  alarm (BENCHMARK_DURATION);
+
+  cur = do_benchmark (&iters);
+
+  struct rusage usage;
+  getrusage(RUSAGE_SELF, &usage);
+
+  d_total_s = cur;
+  d_total_i = iters;
+
+  json_attr_double (&json_ctx, "duration", d_total_s);
+  json_attr_double (&json_ctx, "iterations", d_total_i);
+  json_attr_double (&json_ctx, "time_per_iteration", d_total_s / d_total_i);
+  json_attr_double (&json_ctx, "max_rss", usage.ru_maxrss);
+
+  json_attr_double (&json_ctx, "min_size", MIN_ALLOCATION_SIZE);
+  json_attr_double (&json_ctx, "max_size", MAX_ALLOCATION_SIZE);
+  json_attr_double (&json_ctx, "random_seed", RAND_SEED);
+
+  json_attr_object_end (&json_ctx);
+
+  json_attr_object_end (&json_ctx);
+
+  json_attr_object_end (&json_ctx);
+
+  json_document_end (&json_ctx);
+
+  return 0;
+}
-- 
1.9.3