[PATCH v1 7/7] Bench: Improve benchtests for memchr, strchr, strnlen, strrchr

Noah Goldstein goldstein.w.n@gmail.com
Tue Oct 18 02:49:01 GMT 2022


1. Add more complete coverage in the medium size range.
2. In strnlen remove the `1 << i` which was UB (`i` could go beyond
   32/64)
3. Add timer for total benchmark runtime (useful for deciding about
   tradeoff between coverage and runtime).
---
 benchtests/bench-memchr.c    | 83 +++++++++++++++++++++++++-----------
 benchtests/bench-rawmemchr.c | 36 ++++++++++++++--
 benchtests/bench-strchr.c    | 42 +++++++++++++-----
 benchtests/bench-strnlen.c   | 19 ++++++---
 benchtests/bench-strrchr.c   | 33 +++++++++++++-
 5 files changed, 166 insertions(+), 47 deletions(-)

diff --git a/benchtests/bench-memchr.c b/benchtests/bench-memchr.c
index 0facda2fa0..c4d758ae61 100644
--- a/benchtests/bench-memchr.c
+++ b/benchtests/bench-memchr.c
@@ -126,9 +126,10 @@ do_test (json_ctx_t *json_ctx, size_t align, size_t pos, size_t len,
 int
 test_main (void)
 {
-  size_t i;
+  size_t i, j, al, al_max;
   int repeats;
   json_ctx_t json_ctx;
+  timing_t bench_start, bench_stop, bench_total_time;
   test_init ();
 
   json_init (&json_ctx, 0, stdout);
@@ -147,35 +148,47 @@ test_main (void)
 
   json_array_begin (&json_ctx, "results");
 
+  TIMING_NOW (bench_start);
+  al_max = 0;
+#ifdef USE_AS_MEMRCHR
+  al_max = getpagesize () / 2;
+#endif
+
   for (repeats = 0; repeats < 2; ++repeats)
     {
-      for (i = 1; i < 8; ++i)
+      for (al = 0; al <= al_max; al += getpagesize () / 2)
 	{
-	  do_test (&json_ctx, 0, 16 << i, 2048, 23, repeats);
-	  do_test (&json_ctx, i, 64, 256, 23, repeats);
-	  do_test (&json_ctx, 0, 16 << i, 2048, 0, repeats);
-	  do_test (&json_ctx, i, 64, 256, 0, repeats);
-
-	  do_test (&json_ctx, getpagesize () - 15, 64, 256, 0, repeats);
+	  for (i = 1; i < 8; ++i)
+	    {
+	      do_test (&json_ctx, al, 16 << i, 2048, 23, repeats);
+	      do_test (&json_ctx, al + i, 64, 256, 23, repeats);
+	      do_test (&json_ctx, al, 16 << i, 2048, 0, repeats);
+	      do_test (&json_ctx, al + i, 64, 256, 0, repeats);
+
+	      do_test (&json_ctx, al + getpagesize () - 15, 64, 256, 0,
+		       repeats);
 #ifdef USE_AS_MEMRCHR
-	  /* Also test the position close to the beginning for memrchr.  */
-	  do_test (&json_ctx, 0, i, 256, 23, repeats);
-	  do_test (&json_ctx, 0, i, 256, 0, repeats);
-	  do_test (&json_ctx, i, i, 256, 23, repeats);
-	  do_test (&json_ctx, i, i, 256, 0, repeats);
+	      /* Also test the position close to the beginning for memrchr.  */
+	      do_test (&json_ctx, al, i, 256, 23, repeats);
+	      do_test (&json_ctx, al, i, 256, 0, repeats);
+	      do_test (&json_ctx, al + i, i, 256, 23, repeats);
+	      do_test (&json_ctx, al + i, i, 256, 0, repeats);
 #endif
+	    }
+	  for (i = 1; i < 8; ++i)
+	    {
+	      do_test (&json_ctx, al + i, i << 5, 192, 23, repeats);
+	      do_test (&json_ctx, al + i, i << 5, 192, 0, repeats);
+	      do_test (&json_ctx, al + i, i << 5, 256, 23, repeats);
+	      do_test (&json_ctx, al + i, i << 5, 256, 0, repeats);
+	      do_test (&json_ctx, al + i, i << 5, 512, 23, repeats);
+	      do_test (&json_ctx, al + i, i << 5, 512, 0, repeats);
+
+	      do_test (&json_ctx, al + getpagesize () - 15, i << 5, 256, 23,
+		       repeats);
+	    }
 	}
-      for (i = 1; i < 8; ++i)
-	{
-	  do_test (&json_ctx, i, i << 5, 192, 23, repeats);
-	  do_test (&json_ctx, i, i << 5, 192, 0, repeats);
-	  do_test (&json_ctx, i, i << 5, 256, 23, repeats);
-	  do_test (&json_ctx, i, i << 5, 256, 0, repeats);
-	  do_test (&json_ctx, i, i << 5, 512, 23, repeats);
-	  do_test (&json_ctx, i, i << 5, 512, 0, repeats);
-
-	  do_test (&json_ctx, getpagesize () - 15, i << 5, 256, 23, repeats);
-	}
+
       for (i = 1; i < 32; ++i)
 	{
 	  do_test (&json_ctx, 0, i, i + 1, 23, repeats);
@@ -207,11 +220,33 @@ test_main (void)
 	  do_test (&json_ctx, 0, 2, i + 1, 0, repeats);
 #endif
 	}
+      for (al = 0; al <= al_max; al += getpagesize () / 2)
+	{
+	  for (i = (16 / sizeof (CHAR)); i <= (8192 / sizeof (CHAR)); i += i)
+	    {
+	      for (j = 0; j <= (384 / sizeof (CHAR));
+		   j += (32 / sizeof (CHAR)))
+		{
+		  do_test (&json_ctx, al, i + j, i, 23, repeats);
+		  do_test (&json_ctx, al, i, i + j, 23, repeats);
+		  if (j < i)
+		    {
+		      do_test (&json_ctx, al, i - j, i, 23, repeats);
+		      do_test (&json_ctx, al, i, i - j, 23, repeats);
+		    }
+		}
+	    }
+	}
+
 #ifndef USE_AS_MEMRCHR
       break;
 #endif
     }
 
+  TIMING_NOW (bench_stop);
+  TIMING_DIFF (bench_total_time, bench_start, bench_stop);
+  json_attr_double (&json_ctx, "benchtime", bench_total_time);
+
   json_array_end (&json_ctx);
   json_attr_object_end (&json_ctx);
   json_attr_object_end (&json_ctx);
diff --git a/benchtests/bench-rawmemchr.c b/benchtests/bench-rawmemchr.c
index b1803afc14..667ecd48f9 100644
--- a/benchtests/bench-rawmemchr.c
+++ b/benchtests/bench-rawmemchr.c
@@ -70,7 +70,7 @@ do_test (json_ctx_t *json_ctx, size_t align, size_t pos, size_t len, int seek_ch
   size_t i;
   char *result;
 
-  align &= 7;
+  align &= getpagesize () - 1;
   if (align + len >= page_size)
     return;
 
@@ -106,7 +106,7 @@ test_main (void)
 {
   json_ctx_t json_ctx;
   size_t i;
-
+  timing_t bench_start, bench_stop, bench_total_time;
   test_init ();
 
   json_init (&json_ctx, 0, stdout);
@@ -120,11 +120,12 @@ test_main (void)
 
   json_array_begin (&json_ctx, "ifuncs");
   FOR_EACH_IMPL (impl, 0)
-      json_element_string (&json_ctx, impl->name);
+    json_element_string (&json_ctx, impl->name);
   json_array_end (&json_ctx);
 
   json_array_begin (&json_ctx, "results");
 
+  TIMING_NOW (bench_start);
   for (i = 1; i < 7; ++i)
     {
       do_test (&json_ctx, 0, 16 << i, 2048, 23);
@@ -137,6 +138,35 @@ test_main (void)
       do_test (&json_ctx, 0, i, i + 1, 23);
       do_test (&json_ctx, 0, i, i + 1, 0);
     }
+  for (; i < 256; i += 32)
+    {
+      do_test (&json_ctx, 0, i, i + 1, 23);
+      do_test (&json_ctx, 0, i - 1, i, 23);
+    }
+  for (; i < 512; i += 64)
+    {
+      do_test (&json_ctx, 0, i, i + 1, 23);
+      do_test (&json_ctx, 0, i - 1, i, 23);
+    }
+  for (; i < 1024; i += 128)
+    {
+      do_test (&json_ctx, 0, i, i + 1, 23);
+      do_test (&json_ctx, 0, i - 1, i, 23);
+    }
+  for (; i < 2048; i += 256)
+    {
+      do_test (&json_ctx, 0, i, i + 1, 23);
+      do_test (&json_ctx, 0, i - 1, i, 23);
+    }
+  for (; i < 4096; i += 512)
+    {
+      do_test (&json_ctx, 0, i, i + 1, 23);
+      do_test (&json_ctx, 0, i - 1, i, 23);
+    }
+
+  TIMING_NOW (bench_stop);
+  TIMING_DIFF (bench_total_time, bench_start, bench_stop);
+  json_attr_double (&json_ctx, "benchtime", bench_total_time);
 
   json_array_end (&json_ctx);
   json_attr_object_end (&json_ctx);
diff --git a/benchtests/bench-strchr.c b/benchtests/bench-strchr.c
index 54640bde7e..af325806ce 100644
--- a/benchtests/bench-strchr.c
+++ b/benchtests/bench-strchr.c
@@ -287,8 +287,8 @@ int
 test_main (void)
 {
   json_ctx_t json_ctx;
-  size_t i;
-
+  size_t i, j;
+  timing_t bench_start, bench_stop, bench_total_time;
   test_init ();
 
   json_init (&json_ctx, 0, stdout);
@@ -307,6 +307,7 @@ test_main (void)
 
   json_array_begin (&json_ctx, "results");
 
+  TIMING_NOW (bench_start);
   for (i = 1; i < 8; ++i)
     {
       do_test (&json_ctx, 0, 16 << i, 2048, SMALL_CHAR, MIDDLE_CHAR);
@@ -367,15 +368,34 @@ test_main (void)
       do_test (&json_ctx, 0, i, i + 1, 0, BIG_CHAR);
     }
 
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.0);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.1);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.25);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.33);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.5);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.66);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.75);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 0.9);
-  DO_RAND_TEST(&json_ctx, 0, 15, 16, 1.0);
+  for (i = 16 / sizeof (CHAR); i <= 8192 / sizeof (CHAR); i += i)
+    {
+      for (j = 32 / sizeof (CHAR); j <= 320 / sizeof (CHAR);
+	   j += 32 / sizeof (CHAR))
+	{
+	  do_test (&json_ctx, 0, i, i + j, 0, MIDDLE_CHAR);
+	  do_test (&json_ctx, 0, i + j, i, 0, MIDDLE_CHAR);
+	  if (i > j)
+	    {
+	      do_test (&json_ctx, 0, i, i - j, 0, MIDDLE_CHAR);
+	      do_test (&json_ctx, 0, i - j, i, 0, MIDDLE_CHAR);
+	    }
+	}
+    }
+
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.0);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.1);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.25);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.33);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.5);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.66);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.75);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 0.9);
+  DO_RAND_TEST (&json_ctx, 0, 15, 16, 1.0);
+
+  TIMING_NOW (bench_stop);
+  TIMING_DIFF (bench_total_time, bench_start, bench_stop);
+  json_attr_double (&json_ctx, "benchtime", bench_total_time);
 
   json_array_end (&json_ctx);
   json_attr_object_end (&json_ctx);
diff --git a/benchtests/bench-strnlen.c b/benchtests/bench-strnlen.c
index 13b46b3f57..c6281b6373 100644
--- a/benchtests/bench-strnlen.c
+++ b/benchtests/bench-strnlen.c
@@ -117,7 +117,7 @@ test_main (void)
 {
   size_t i, j;
   json_ctx_t json_ctx;
-
+  timing_t bench_start, bench_stop, bench_total_time;
   test_init ();
 
   json_init (&json_ctx, 0, stdout);
@@ -136,6 +136,7 @@ test_main (void)
 
   json_array_begin (&json_ctx, "results");
 
+  TIMING_NOW (bench_start);
   for (i = 0; i <= 1; ++i)
     {
       do_test (&json_ctx, i, 1, 128, MIDDLE_CHAR);
@@ -195,23 +196,27 @@ test_main (void)
     {
       for (j = 0; j <= (704 / sizeof (CHAR)); j += (32 / sizeof (CHAR)))
 	{
-	  do_test (&json_ctx, 0, 1 << i, (i + j), BIG_CHAR);
 	  do_test (&json_ctx, 0, i + j, i, BIG_CHAR);
-
-	  do_test (&json_ctx, 64, 1 << i, (i + j), BIG_CHAR);
 	  do_test (&json_ctx, 64, i + j, i, BIG_CHAR);
 
+	  do_test (&json_ctx, 0, i, i + j, BIG_CHAR);
+	  do_test (&json_ctx, 64, i, i + j, BIG_CHAR);
+
 	  if (j < i)
 	    {
-	      do_test (&json_ctx, 0, 1 << i, i - j, BIG_CHAR);
 	      do_test (&json_ctx, 0, i - j, i, BIG_CHAR);
-
-	      do_test (&json_ctx, 64, 1 << i, i - j, BIG_CHAR);
 	      do_test (&json_ctx, 64, i - j, i, BIG_CHAR);
+
+	      do_test (&json_ctx, 0, i, i - j, BIG_CHAR);
+	      do_test (&json_ctx, 64, i, i - j, BIG_CHAR);
 	    }
 	}
     }
 
+  TIMING_NOW (bench_stop);
+  TIMING_DIFF (bench_total_time, bench_start, bench_stop);
+  json_attr_double (&json_ctx, "benchtime", bench_total_time);
+
   json_array_end (&json_ctx);
   json_attr_object_end (&json_ctx);
   json_attr_object_end (&json_ctx);
diff --git a/benchtests/bench-strrchr.c b/benchtests/bench-strrchr.c
index 7cd2a15484..e6d8163047 100644
--- a/benchtests/bench-strrchr.c
+++ b/benchtests/bench-strrchr.c
@@ -151,8 +151,9 @@ int
 test_main (void)
 {
   json_ctx_t json_ctx;
-  size_t i, j;
+  size_t i, j, k;
   int seek;
+  timing_t bench_start, bench_stop, bench_total_time;
 
   test_init ();
   json_init (&json_ctx, 0, stdout);
@@ -171,9 +172,10 @@ test_main (void)
 
   json_array_begin (&json_ctx, "results");
 
+  TIMING_NOW (bench_start);
   for (seek = 0; seek <= 23; seek += 23)
     {
-      for (j = 1; j < 32; j += j)
+      for (j = 1; j <= 256; j = (j * 4))
 	{
 	  for (i = 1; i < 9; ++i)
 	    {
@@ -197,12 +199,39 @@ test_main (void)
 	      do_test (&json_ctx, getpagesize () - i / 2 - 1, i, i + 1, seek,
 		       SMALL_CHAR, j);
 	    }
+
+	  for (i = (16 / sizeof (CHAR)); i <= (288 / sizeof (CHAR)); i += 32)
+	    {
+	      do_test (&json_ctx, 0, i - 16, i, seek, SMALL_CHAR, j);
+	      do_test (&json_ctx, 0, i, i + 16, seek, SMALL_CHAR, j);
+	    }
+
+	  for (i = (16 / sizeof (CHAR)); i <= (2048 / sizeof (CHAR)); i += i)
+	    {
+	      for (k = 0; k <= (288 / sizeof (CHAR));
+		   k += (48 / sizeof (CHAR)))
+		{
+		  do_test (&json_ctx, 0, k, i, seek, SMALL_CHAR, j);
+		  do_test (&json_ctx, 0, i, i + k, seek, SMALL_CHAR, j);
+
+		  if (k < i)
+		    {
+		      do_test (&json_ctx, 0, i - k, i, seek, SMALL_CHAR, j);
+		      do_test (&json_ctx, 0, k, i - k, seek, SMALL_CHAR, j);
+		      do_test (&json_ctx, 0, i, i - k, seek, SMALL_CHAR, j);
+		    }
+		}
+	    }
+
 	  if (seek == 0)
 	    {
 	      break;
 	    }
 	}
     }
+  TIMING_NOW (bench_stop);
+  TIMING_DIFF (bench_total_time, bench_start, bench_stop);
+  json_attr_double (&json_ctx, "benchtime", bench_total_time);
 
   json_array_end (&json_ctx);
   json_attr_object_end (&json_ctx);
-- 
2.34.1



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