benchtests: Add malloc microbenchmark

Add a microbenchmark for measuring malloc and free performance with
varying numbers of threads. The benchmark allocates and frees buffers
of random sizes in a random order and measures the overall execution
time and RSS. Variants of the benchmark are run with 1, 8, 16 and
32 threads.

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:

2014-11-05  Will Newton  <will.newton@linaro.org>

	* benchtests/Makefile: (bench-malloc): Add malloc thread
	scalability benchmark.
	* benchtests/bench-malloc-threads.c: New file.

1 files changed, 302 insertions, 0 deletions

diff --git a/benchtests/bench-malloc-thread.c b/benchtests/bench-malloc-thread.c
new file mode 100644
index 0000000000..d8798cfd85
--- /dev/null
+++ b/benchtests/bench-malloc-thread.c
@@ -0,0 +1,302 @@
+/* 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 <pthread.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
+
+#ifndef NUM_THREADS
+# define NUM_THREADS 1
+#endif
+
+/* Maximum memory that can be allocated at any one time is:
+
+   NUM_THREADS * 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;
+}
+
+struct thread_args
+{
+  size_t iters;
+  void **working_set;
+  timing_t elapsed;
+};
+
+static void *
+benchmark_thread (void *arg)
+{
+  struct thread_args *args = (struct thread_args *) arg;
+  size_t iters;
+  void *thread_set = args->working_set;
+  timing_t start, stop;
+
+  TIMING_NOW (start);
+  iters = malloc_benchmark_loop (thread_set);
+  TIMING_NOW (stop);
+
+  TIMING_DIFF (args->elapsed, start, stop);
+  args->iters = iters;
+
+  return NULL;
+}
+
+static timing_t
+do_benchmark (size_t num_threads, size_t *iters)
+{
+  timing_t elapsed = 0;
+
+  if (num_threads == 1)
+    {
+      timing_t 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);
+    }
+  else
+    {
+      struct thread_args args[num_threads];
+      void *working_set[num_threads][WORKING_SET_SIZE];
+      pthread_t threads[num_threads];
+
+      memset (working_set, 0, sizeof (working_set));
+
+      *iters = 0;
+
+      for (size_t i = 0; i < num_threads; i++)
+	{
+	  args[i].working_set = working_set[i];
+	  pthread_create(&threads[i], NULL, benchmark_thread, &args[i]);
+	}
+
+      for (size_t i = 0; i < num_threads; i++)
+	{
+	  pthread_join(threads[i], NULL);
+	  TIMING_ACCUM (elapsed, args[i].elapsed);
+	  *iters += args[i].iters;
+	}
+    }
+  return elapsed;
+}
+
+static void usage(const char *name)
+{
+  fprintf (stderr, "%s: <num_threads>\n", name);
+  exit (1);
+}
+
+int
+main (int argc, char **argv)
+{
+  timing_t cur;
+  size_t iters = 0, num_threads = 1;
+  unsigned long res;
+  json_ctx_t json_ctx;
+  double d_total_s, d_total_i;
+  struct sigaction act;
+
+  if (argc == 1)
+    num_threads = 1;
+  else if (argc == 2)
+    {
+      long ret;
+
+      errno = 0;
+      ret = strtol(argv[1], NULL, 10);
+
+      if (errno || ret == 0)
+	usage(argv[0]);
+
+      num_threads = ret;
+    }
+  else
+    usage(argv[0]);
+
+  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 (num_threads, &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, "threads", num_threads);
+  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;
+}