benchtests/bench-pthread-mutex-locks.c

   1 /* Measure mutex_lock for different threads and critical sections.
   2    Copyright (C) 2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #define TEST_MAIN
  20 #define TEST_NAME "pthread-mutex-locks"
  21 #define TIMEOUT (20 * 60)
  22
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <math.h>
  28 #include <pthread.h>
  29 #include <sys/time.h>
  30 #include <sys/sysinfo.h>
  31 #include "bench-timing.h"
  32 #include "json-lib.h"
  33
  34 static pthread_mutex_t lock;
  35 static pthread_mutexattr_t attr;
  36 static pthread_barrier_t barrier;
  37
  38 #define START_ITERS 1000
  39
  40 #pragma GCC push_options
  41 #pragma GCC optimize(1)
  42
  43 static int __attribute__ ((noinline)) fibonacci (int i)
  44 {
  45   asm("");
  46   if (i > 2)
  47     return fibonacci (i - 1) + fibonacci (i - 2);
  48   return 10 + i;
  49 }
  50
  51 static void
  52 do_filler (void)
  53 {
  54   char buf1[512], buf2[512];
  55   int f = fibonacci (4);
  56   memcpy (buf1, buf2, f);
  57 }
  58
  59 static void
  60 do_filler_shared (void)
  61 {
  62   static char buf1[512], buf2[512];
  63   int f = fibonacci (4);
  64   memcpy (buf1, buf2, f);
  65 }
  66
  67 #pragma GCC pop_options
  68
  69 #define UNIT_WORK_CRT do_filler_shared ()
  70 #define UNIT_WORK_NON_CRT do_filler ()
  71
  72 static inline void
  73 critical_section (int length)
  74 {
  75   for (int i = length; i >= 0; i--)
  76     UNIT_WORK_CRT;
  77 }
  78
  79 static inline void
  80 non_critical_section (int length)
  81 {
  82   for (int i = length; i >= 0; i--)
  83     UNIT_WORK_NON_CRT;
  84 }
  85
  86 typedef struct Worker_Params
  87 {
  88   long iters;
  89   int crt_len;
  90   int non_crt_len;
  91   timing_t duration;
  92 } Worker_Params;
  93
  94 static void *
  95 worker (void *v)
  96 {
  97   timing_t start, stop;
  98   Worker_Params *p = (Worker_Params *) v;
  99   long iters = p->iters;
 100   int crt_len = p->crt_len;
 101   int non_crt_len = p->non_crt_len;
 102
 103   pthread_barrier_wait (&barrier);
 104   TIMING_NOW (start);
 105   while (iters--)
 106     {
 107       pthread_mutex_lock (&lock);
 108       critical_section (crt_len);
 109       pthread_mutex_unlock (&lock);
 110       non_critical_section (non_crt_len);
 111     }
 112   TIMING_NOW (stop);
 113
 114   TIMING_DIFF (p->duration, start, stop);
 115   return NULL;
 116 }
 117
 118 static double
 119 do_one_test (int num_threads, int crt_len, int non_crt_len, long iters)
 120 {
 121   int i;
 122   timing_t mean;
 123   Worker_Params *p, params[num_threads];
 124   pthread_t threads[num_threads];
 125
 126   pthread_mutex_init (&lock, &attr);
 127   pthread_barrier_init (&barrier, NULL, num_threads);
 128
 129   for (i = 0; i < num_threads; i++)
 130     {
 131       p = &params[i];
 132       p->iters = iters;
 133       p->crt_len = crt_len;
 134       p->non_crt_len = non_crt_len;
 135       pthread_create (&threads[i], NULL, worker, (void *) p);
 136     }
 137   for (i = 0; i < num_threads; i++)
 138     pthread_join (threads[i], NULL);
 139
 140   pthread_mutex_destroy (&lock);
 141   pthread_barrier_destroy (&barrier);
 142
 143   mean = 0;
 144   for (i = 0; i < num_threads; i++)
 145     mean += params[i].duration;
 146   mean /= num_threads;
 147   return mean;
 148 }
 149
 150 #define RUN_COUNT 10
 151 #define MIN_TEST_SEC 0.01
 152
 153 static void
 154 do_bench_one (const char *name, int num_threads, int crt_len, int non_crt_len,
 155               json_ctx_t *js)
 156 {
 157   timing_t cur;
 158   struct timeval ts, te;
 159   double tsd, ted, td;
 160   long iters, iters_limit, total_iters;
 161   timing_t curs[RUN_COUNT + 2];
 162   int i, j;
 163   double mean, stdev;
 164
 165   iters = START_ITERS;
 166   iters_limit = LONG_MAX / 100;
 167
 168   while (1)
 169     {
 170       gettimeofday (&ts, NULL);
 171       cur = do_one_test (num_threads, crt_len, non_crt_len, iters);
 172       gettimeofday (&te, NULL);
 173       /* Make sure the test to run at least MIN_TEST_SEC.  */
 174       tsd = ts.tv_sec + ts.tv_usec / 1000000.0;
 175       ted = te.tv_sec + te.tv_usec / 1000000.0;
 176       td = ted - tsd;
 177       if (td >= MIN_TEST_SEC || iters >= iters_limit)
 178         break;
 179
 180       iters *= 10;
 181     }
 182
 183   curs[0] = cur;
 184   for (i = 1; i < RUN_COUNT + 2; i++)
 185     curs[i] = do_one_test (num_threads, crt_len, non_crt_len, iters);
 186
 187   /* Sort the results so we can discard the fastest and slowest
 188      times as outliers.  */
 189   for (i = 0; i < RUN_COUNT + 1; i++)
 190     for (j = i + 1; j < RUN_COUNT + 2; j++)
 191       if (curs[i] > curs[j])
 192         {
 193           timing_t temp = curs[i];
 194           curs[i] = curs[j];
 195           curs[j] = temp;
 196         }
 197
 198   /* Calculate mean and standard deviation.  */
 199   mean = 0.0;
 200   total_iters = iters * num_threads;
 201   for (i = 1; i < RUN_COUNT + 1; i++)
 202     mean += (double) curs[i] / (double) total_iters;
 203   mean /= RUN_COUNT;
 204
 205   stdev = 0.0;
 206   for (i = 1; i < RUN_COUNT + 1; i++)
 207     {
 208       double s = (double) curs[i] / (double) total_iters - mean;
 209       stdev += s * s;
 210     }
 211   stdev = sqrt (stdev / (RUN_COUNT - 1));
 212
 213   char buf[256];
 214   snprintf (buf, sizeof buf, "%s,non_crt_len=%d,crt_len=%d,threads=%d", name,
 215             non_crt_len, crt_len, num_threads);
 216
 217   json_attr_object_begin (js, buf);
 218
 219   json_attr_double (js, "duration", (double) cur);
 220   json_attr_double (js, "iterations", (double) total_iters);
 221   json_attr_double (js, "mean", mean);
 222   json_attr_double (js, "stdev", stdev);
 223   json_attr_double (js, "min-outlier",
 224                     (double) curs[0] / (double) total_iters);
 225   json_attr_double (js, "min", (double) curs[1] / (double) total_iters);
 226   json_attr_double (js, "max",
 227                     (double) curs[RUN_COUNT] / (double) total_iters);
 228   json_attr_double (js, "max-outlier",
 229                     (double) curs[RUN_COUNT + 1] / (double) total_iters);
 230
 231   json_attr_object_end (js);
 232 }
 233
 234 #define TH_CONF_MAX 10
 235
 236 int
 237 do_bench (void)
 238 {
 239   int rv = 0;
 240   json_ctx_t json_ctx;
 241   int i, j, k;
 242   int th_num, th_conf, nprocs;
 243   int threads[TH_CONF_MAX];
 244   int crt_lens[] = { 0, 1, 2, 4, 8, 16, 32, 64, 128 };
 245   int non_crt_lens[] = { 1, 32, 128 };
 246   char name[128];
 247
 248   json_init (&json_ctx, 2, stdout);
 249   json_attr_object_begin (&json_ctx, "pthread_mutex_locks");
 250
 251   /* The thread config begins from 1, and increases by 2x until nprocs.
 252      We also wants to test over-saturation case (1.25*nprocs).  */
 253   nprocs = get_nprocs ();
 254   th_num = 1;
 255   for (th_conf = 0; th_conf < (TH_CONF_MAX - 2) && th_num < nprocs; th_conf++)
 256     {
 257       threads[th_conf] = th_num;
 258       th_num <<= 1;
 259     }
 260   threads[th_conf++] = nprocs;
 261   threads[th_conf++] = nprocs + nprocs / 4;
 262
 263   pthread_mutexattr_init (&attr);
 264   pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
 265   snprintf (name, sizeof name, "type=adaptive");
 266
 267   for (k = 0; k < (sizeof (non_crt_lens) / sizeof (int)); k++)
 268     {
 269       int non_crt_len = non_crt_lens[k];
 270       for (j = 0; j < (sizeof (crt_lens) / sizeof (int)); j++)
 271         {
 272           int crt_len = crt_lens[j];
 273           for (i = 0; i < th_conf; i++)
 274             {
 275               th_num = threads[i];
 276               do_bench_one (name, th_num, crt_len, non_crt_len, &json_ctx);
 277             }
 278         }
 279     }
 280
 281   json_attr_object_end (&json_ctx);
 282
 283   return rv;
 284 }
 285
 286 #define TEST_FUNCTION do_bench ()
 287
 288 #include "../test-skeleton.c"