test/test_rand_perf.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2019 Ericsson AB
   3  */
   4
   5 #include <inttypes.h>
   6 #include <stdio.h>
   7
   8 #include <rte_common.h>
   9 #include <rte_cycles.h>
  10 #include <rte_random.h>
  11
  12 #include "test.h"
  13
  14 static volatile uint64_t vsum;
  15
  16 #define ITERATIONS (100000000)
  17
  18 #define BEST_CASE_BOUND (1<<16)
  19 #define WORST_CASE_BOUND (BEST_CASE_BOUND + 1)
  20
  21 enum rand_type {
  22         rand_type_64,
  23         rand_type_float,
  24         rand_type_bounded_best_case,
  25         rand_type_bounded_worst_case
  26 };
  27
  28 static const char *
  29 rand_type_desc(enum rand_type rand_type)
  30 {
  31         switch (rand_type) {
  32         case rand_type_64:
  33                 return "Full 64-bit [rte_rand()]";
  34         case rand_type_float:
  35                 return "Floating point [rte_drand()]";
  36         case rand_type_bounded_best_case:
  37                 return "Bounded average best-case [rte_rand_max()]";
  38         case rand_type_bounded_worst_case:
  39                 return "Bounded average worst-case [rte_rand_max()]";
  40         default:
  41                 return NULL;
  42         }
  43 }
  44
  45 static __rte_always_inline void
  46 test_rand_perf_type(enum rand_type rand_type)
  47 {
  48         uint64_t start;
  49         uint32_t i;
  50         uint64_t end;
  51         uint64_t sum = 0;
  52         uint64_t op_latency;
  53
  54         start = rte_rdtsc();
  55
  56         for (i = 0; i < ITERATIONS; i++) {
  57                 switch (rand_type) {
  58                 case rand_type_64:
  59                         sum += rte_rand();
  60                         break;
  61                 case rand_type_float:
  62                         sum += 1000. * rte_drand();
  63                         break;
  64                 case rand_type_bounded_best_case:
  65                         sum += rte_rand_max(BEST_CASE_BOUND);
  66                         break;
  67                 case rand_type_bounded_worst_case:
  68                         sum += rte_rand_max(WORST_CASE_BOUND);
  69                         break;
  70                 }
  71         }
  72
  73         end = rte_rdtsc();
  74
  75         /* to avoid an optimizing compiler removing the whole loop */
  76         vsum = sum;
  77
  78         op_latency = (end - start) / ITERATIONS;
  79
  80         printf("%s: %"PRId64" TSC cycles/op\n", rand_type_desc(rand_type),
  81                op_latency);
  82 }
  83
  84 static int
  85 test_rand_perf(void)
  86 {
  87         rte_srand(42);
  88
  89         printf("Pseudo-random number generation latencies:\n");
  90
  91         test_rand_perf_type(rand_type_64);
  92         test_rand_perf_type(rand_type_float);
  93         test_rand_perf_type(rand_type_bounded_best_case);
  94         test_rand_perf_type(rand_type_bounded_worst_case);
  95
  96         return 0;
  97 }
  98
  99 REGISTER_TEST_COMMAND(rand_perf_autotest, test_rand_perf);