[PATCH 1/3] Copy over string performance tests - take 2

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

I had held back my earlier patch to start moving string performance
tests from string/test-* to benchtests because Ondrej expresed
interest in writing better tests.  We're close to a freeze and I
didn't see any submissions from Ondrej, so I've decided to revive this
patch so that we at least have a starting point for string performance
tests.

This patch introduces a new feature to the benchmark suite where one
could run separate set of benchmark tests to get a separate output.
This is useful for cases where a benchmark run needs to measure more
than just the number of cycles consumed per function call, which is
where the default bench.out is useful.

As an example use case, I've copied over the memcpy string performance
tests, with the correctness tests removed since they're not useful in
the benchmark.  I've also added a description to the README.

There are also two follow-up patches that I'll post shortly:

1) Copy over the remaining string benchmark tests - This is a fairly
   large, but mechanical patch.
2) Remove measurement-related code from the string tests

As a result, we will end up with two distinct sets of tests - the
correctness tests run with make check and the benchmark tests run with
make bench.

Siddhesh

	* benchtests/Makefile: Disable parallel execution of targets.
	(string-bench): Add memcpy.
	(benchset): New variable to store a list of benchmark sets.
	(bench-func): Renamed from bench.
	(bench-set): New target.
	(bench): Depend on bench-func and bench-set.
	* benchtests/README: Add section on benchmark sets.
	* benchtests/bench-memcpy-ifunc.c: New file.
	* benchtests/bench-memcpy.c: New file.
	* benchtests/bench-string.h: New file.

diff --git a/benchtests/Makefile b/benchtests/Makefile
index 680440f..a7c8082 100644
--- a/benchtests/Makefile
+++ b/benchtests/Makefile
@@ -23,6 +23,13 @@ subdir := benchtests
 bench := acos acosh asin asinh atan atanh cos cosh exp log modf pow rint sin \
 	 sinh tan tanh
 
+# String function benchmarks.
+string-bench := memcpy
+string-bench-ifunc := $(addsuffix -ifunc, $(string-bench))
+string-bench-all := $(string-bench) $(string-bench-ifunc)
+
+benchset := $(string-bench-all)
+
 acos-ARGLIST = double
 acos-RET = double
 LDFLAGS-bench-acos = -lm
@@ -92,10 +99,13 @@ LDFLAGS-bench-tanh = -lm
 # Rules to build and execute the benchmarks.  Do not put any benchmark
 # parameters beyond this point.
 
+.NOTPARALLEL:
+
 include ../Makeconfig
 include ../Rules
 
 binaries-bench := $(addprefix $(objpfx)bench-,$(bench))
+binaries-benchset := $(addprefix $(objpfx)bench-,$(benchset))
 
 # The default duration: 10 seconds.
 ifndef BENCH_DURATION
@@ -112,7 +122,7 @@ endif
 
 # This makes sure CPPFLAGS-nonlib and CFLAGS-nonlib are passed
 # for all these modules.
-cpp-srcs-left := $(binaries-bench:=.c)
+cpp-srcs-left := $(binaries-benchset:=.c) $(binaries-bench:=.c)
 lib := nonlib
 include $(patsubst %,$(..)cppflags-iterator.mk,$(cpp-srcs-left))
 
@@ -124,8 +134,17 @@ run-bench = $(test-wrapper-env) \
 
 bench-clean:
 	rm -f $(binaries-bench) $(addsuffix .o,$(binaries-bench))
+	rm -f $(binaries-benchset) $(addsuffix .o,$(binaries-benchset))
+
+bench: bench-set bench-func
+
+bench-set: $(binaries-benchset)
+	for run in $^; do \
+	  echo "Running $${run}"; \
+	  $(run-bench) > $${run}.out; \
+	done
 
-bench: $(binaries-bench)
+bench-func: $(binaries-bench)
 	{ for run in $^; do \
 	  echo "Running $${run}" >&2; \
 	  $(run-bench); \
@@ -135,7 +154,7 @@ bench: $(binaries-bench)
 	fi; \
 	mv -f $(objpfx)bench.out-tmp $(objpfx)bench.out
 
-$(binaries-bench): %: %.o \
+$(binaries-bench) $(binaries-benchset): %: %.o \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link)
diff --git a/benchtests/README b/benchtests/README
index 8135069..06cfcc5 100644
--- a/benchtests/README
+++ b/benchtests/README
@@ -72,3 +72,18 @@ the same file by using the `name' directive that looks something like this:
 
 See the pow-inputs file for an example of what such a partitioned input file
 would look like.
+
+Benchmark Sets:
+==============
+
+In addition to standard benchmarking of functions, one may also generate
+custom outputs for a set of functions.  This is currentlyy used by string
+function benchmarks where the aim is to compare performance between
+implementations at various alignments and for various sizes.
+
+To add a benchset for `foo':
+
+- Add `foo' to the benchset variable.
+- Write your bench-foo.c that prints out the measurements to stdout.
+- On execution, a bench-foo.out is created in $(objpfx) with the contents of
+  stdout.
diff --git a/benchtests/bench-memcpy-ifunc.c b/benchtests/bench-memcpy-ifunc.c
new file mode 100644
index 0000000..b5a89f7
--- /dev/null
+++ b/benchtests/bench-memcpy-ifunc.c
@@ -0,0 +1,20 @@
+/* Measure IFUNC implementations of memcpy function.
+   Copyright (C) 2013 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/>.  */
+
+#define TEST_IFUNC 1
+#include "bench-memcpy.c"
diff --git a/benchtests/bench-memcpy.c b/benchtests/bench-memcpy.c
new file mode 100644
index 0000000..1b12671
--- /dev/null
+++ b/benchtests/bench-memcpy.c
@@ -0,0 +1,163 @@
+/* Measure memcpy functions.
+   Copyright (C) 2013 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/>.  */
+
+#ifndef MEMCPY_RESULT
+# define MEMCPY_RESULT(dst, len) dst
+# define MIN_PAGE_SIZE 131072
+# define TEST_MAIN
+# define TEST_NAME "memcpy"
+# include "bench-string.h"
+
+char *simple_memcpy (char *, const char *, size_t);
+char *builtin_memcpy (char *, const char *, size_t);
+
+IMPL (simple_memcpy, 0)
+IMPL (builtin_memcpy, 0)
+IMPL (memcpy, 1)
+
+char *
+simple_memcpy (char *dst, const char *src, size_t n)
+{
+  char *ret = dst;
+  while (n--)
+    *dst++ = *src++;
+  return ret;
+}
+
+char *
+builtin_memcpy (char *dst, const char *src, size_t n)
+{
+  return __builtin_memcpy (dst, src, n);
+}
+#endif
+
+typedef char *(*proto_t) (char *, const char *, size_t);
+
+static void
+do_one_test (impl_t *impl, char *dst, const char *src,
+	     size_t len)
+{
+  if (CALL (impl, dst, src, len) != MEMCPY_RESULT (dst, len))
+    {
+      error (0, 0, "Wrong result in function %s %p %p", impl->name,
+	     CALL (impl, dst, src, len), MEMCPY_RESULT (dst, len));
+      ret = 1;
+      return;
+    }
+
+  if (memcmp (dst, src, len) != 0)
+    {
+      error (0, 0, "Wrong result in function %s dst \"%s\" src \"%s\"",
+	     impl->name, dst, src);
+      ret = 1;
+      return;
+    }
+
+  if (HP_TIMING_AVAIL)
+    {
+      hp_timing_t start __attribute ((unused));
+      hp_timing_t stop __attribute ((unused));
+      hp_timing_t best_time = ~ (hp_timing_t) 0;
+      size_t i;
+
+      for (i = 0; i < 32; ++i)
+	{
+	  HP_TIMING_NOW (start);
+	  CALL (impl, dst, src, len);
+	  HP_TIMING_NOW (stop);
+	  HP_TIMING_BEST (best_time, start, stop);
+	}
+
+      printf ("\t%zd", (size_t) best_time);
+    }
+}
+
+static void
+do_test (size_t align1, size_t align2, size_t len)
+{
+  size_t i, j;
+  char *s1, *s2;
+
+  align1 &= 63;
+  if (align1 + len >= page_size)
+    return;
+
+  align2 &= 63;
+  if (align2 + len >= page_size)
+    return;
+
+  s1 = (char *) (buf1 + align1);
+  s2 = (char *) (buf2 + align2);
+
+  for (i = 0, j = 1; i < len; i++, j += 23)
+    s1[i] = j;
+
+  if (HP_TIMING_AVAIL)
+    printf ("Length %4zd, alignment %2zd/%2zd:", len, align1, align2);
+
+  FOR_EACH_IMPL (impl, 0)
+    do_one_test (impl, s2, s1, len);
+
+  if (HP_TIMING_AVAIL)
+    putchar ('\n');
+}
+
+int
+test_main (void)
+{
+  size_t i;
+
+  test_init ();
+
+  printf ("%23s", "");
+  FOR_EACH_IMPL (impl, 0)
+    printf ("\t%s", impl->name);
+  putchar ('\n');
+
+  for (i = 0; i < 18; ++i)
+    {
+      do_test (0, 0, 1 << i);
+      do_test (i, 0, 1 << i);
+      do_test (0, i, 1 << i);
+      do_test (i, i, 1 << i);
+    }
+
+  for (i = 0; i < 32; ++i)
+    {
+      do_test (0, 0, i);
+      do_test (i, 0, i);
+      do_test (0, i, i);
+      do_test (i, i, i);
+    }
+
+  for (i = 3; i < 32; ++i)
+    {
+      if ((i & (i - 1)) == 0)
+	continue;
+      do_test (0, 0, 16 * i);
+      do_test (i, 0, 16 * i);
+      do_test (0, i, 16 * i);
+      do_test (i, i, 16 * i);
+    }
+
+  do_test (0, 0, getpagesize ());
+
+  return ret;
+}
+
+#include "../test-skeleton.c"
diff --git a/benchtests/bench-string.h b/benchtests/bench-string.h
new file mode 100644
index 0000000..772377f
--- /dev/null
+++ b/benchtests/bench-string.h
@@ -0,0 +1,212 @@
+/* Measure string and memory functions.
+   Copyright (C) 2013 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 <sys/cdefs.h>
+
+typedef struct
+{
+  const char *name;
+  void (*fn) (void);
+  long test;
+} impl_t;
+extern impl_t __start_impls[], __stop_impls[];
+
+#define IMPL(name, test) \
+  impl_t tst_ ## name							\
+  __attribute__ ((section ("impls"), aligned (sizeof (void *))))	\
+       = { __STRING (name), (void (*) (void))name, test };
+
+#ifdef TEST_MAIN
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#undef __USE_STRING_INLINES
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <error.h>
+#include <errno.h>
+#include <time.h>
+#include <ifunc-impl-list.h>
+#define GL(x) _##x
+#define GLRO(x) _##x
+#include <hp-timing.h>
+
+
+# define TEST_FUNCTION test_main ()
+# define TIMEOUT (4 * 60)
+# define OPT_ITERATIONS 10000
+# define OPT_RANDOM 10001
+# define OPT_SEED 10002
+
+unsigned char *buf1, *buf2;
+int ret, do_srandom;
+unsigned int seed;
+size_t page_size;
+
+hp_timing_t _dl_hp_timing_overhead;
+
+# ifndef ITERATIONS
+size_t iterations = 100000;
+#  define ITERATIONS_OPTIONS \
+  { "iterations", required_argument, NULL, OPT_ITERATIONS },
+#  define ITERATIONS_PROCESS \
+  case OPT_ITERATIONS:				\
+    iterations = strtoul (optarg, NULL, 0);	\
+    break;
+#  define ITERATIONS iterations
+# else
+#  define ITERATIONS_OPTIONS
+#  define ITERATIONS_PROCESS
+# endif
+
+# define CMDLINE_OPTIONS ITERATIONS_OPTIONS \
+  { "random", no_argument, NULL, OPT_RANDOM },	\
+  { "seed", required_argument, NULL, OPT_SEED },
+# define CMDLINE_PROCESS ITERATIONS_PROCESS \
+  case OPT_RANDOM:							\
+    {									\
+      int fdr = open ("/dev/urandom", O_RDONLY);			\
+									\
+      if (fdr < 0 || read (fdr, &seed, sizeof(seed)) != sizeof (seed))	\
+	seed = time (NULL);						\
+      if (fdr >= 0)							\
+	close (fdr);							\
+      do_srandom = 1;							\
+      break;								\
+    }									\
+									\
+  case OPT_SEED:							\
+    seed = strtoul (optarg, NULL, 0);					\
+    do_srandom = 1;							\
+    break;
+
+#define CALL(impl, ...)	\
+  (* (proto_t) (impl)->fn) (__VA_ARGS__)
+
+#if defined TEST_IFUNC && defined TEST_NAME
+/* Increase size of FUNC_LIST if assert is triggered at run-time.  */
+static struct libc_ifunc_impl func_list[32];
+static int func_count;
+static int impl_count = -1;
+static impl_t *impl_array;
+
+# define FOR_EACH_IMPL(impl, notall) \
+  impl_t *impl;								\
+  int count;								\
+  if (impl_count == -1)							\
+    {									\
+      impl_count = 0;							\
+      if (func_count != 0)						\
+	{								\
+	  int f;							\
+	  impl_t *skip = NULL, *a;					\
+	  for (impl = __start_impls; impl < __stop_impls; ++impl)	\
+	    if (strcmp (impl->name, TEST_NAME) == 0)			\
+	      skip = impl;						\
+	    else							\
+	      impl_count++;						\
+	  a = impl_array = malloc ((impl_count + func_count) *		\
+				   sizeof (impl_t));			\
+	  for (impl = __start_impls; impl < __stop_impls; ++impl)	\
+	    if (impl != skip)						\
+	      *a++ = *impl;						\
+	  for (f = 0; f < func_count; f++)				\
+	    if (func_list[f].usable)					\
+	      {								\
+		a->name = func_list[f].name;				\
+		a->fn = func_list[f].fn;				\
+		a->test = 1;						\
+		a++;							\
+	      }								\
+	  impl_count = a - impl_array;					\
+	}								\
+      else								\
+        {								\
+	  impl_count = __stop_impls - __start_impls;			\
+	  impl_array = __start_impls;					\
+        }								\
+    }									\
+  impl = impl_array;							\
+  for (count = 0; count < impl_count; ++count, ++impl)			\
+    if (!notall || impl->test)
+#else
+# define FOR_EACH_IMPL(impl, notall) \
+  for (impl_t *impl = __start_impls; impl < __stop_impls; ++impl)	\
+    if (!notall || impl->test)
+#endif
+
+#define HP_TIMING_BEST(best_time, start, end)	\
+  do									\
+    {									\
+      hp_timing_t tmptime;						\
+      HP_TIMING_DIFF (tmptime, start + _dl_hp_timing_overhead, end);	\
+      if (best_time > tmptime)						\
+	best_time = tmptime;						\
+    }									\
+  while (0)
+
+#ifndef BUF1PAGES
+# define BUF1PAGES 1
+#endif
+
+static void
+test_init (void)
+{
+#if defined TEST_IFUNC && defined TEST_NAME
+  func_count = __libc_ifunc_impl_list (TEST_NAME, func_list,
+				       (sizeof func_list
+					/ sizeof func_list[0]));
+#endif
+
+  page_size = 2 * getpagesize ();
+#ifdef MIN_PAGE_SIZE
+  if (page_size < MIN_PAGE_SIZE)
+    page_size = MIN_PAGE_SIZE;
+#endif
+  buf1 = mmap (0, (BUF1PAGES + 1) * page_size, PROT_READ | PROT_WRITE,
+	       MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (buf1 == MAP_FAILED)
+    error (EXIT_FAILURE, errno, "mmap failed");
+  if (mprotect (buf1 + BUF1PAGES * page_size, page_size, PROT_NONE))
+    error (EXIT_FAILURE, errno, "mprotect failed");
+  buf2 = mmap (0, 2 * page_size, PROT_READ | PROT_WRITE,
+	       MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (buf2 == MAP_FAILED)
+    error (EXIT_FAILURE, errno, "mmap failed");
+  if (mprotect (buf2 + page_size, page_size, PROT_NONE))
+    error (EXIT_FAILURE, errno, "mprotect failed");
+  HP_TIMING_DIFF_INIT ();
+  if (do_srandom)
+    {
+      printf ("Setting seed to 0x%x\n", seed);
+      srandom (seed);
+    }
+
+  memset (buf1, 0xa5, BUF1PAGES * page_size);
+  memset (buf2, 0x5a, page_size);
+}
+
+#endif