app/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_bounded_best_case,
  24         rand_type_bounded_worst_case
  25 };
  26
  27 static const char *
  28 rand_type_desc(enum rand_type rand_type)
  29 {
  30         switch (rand_type) {
  31         case rand_type_64:
  32                 return "Full 64-bit [rte_rand()]";
  33         case rand_type_bounded_best_case:
  34                 return "Bounded average best-case [rte_rand_max()]";
  35         case rand_type_bounded_worst_case:
  36                 return "Bounded average worst-case [rte_rand_max()]";
  37         default:
  38                 return NULL;
  39         }
  40 }
  41
  42 static __rte_always_inline void
  43 test_rand_perf_type(enum rand_type rand_type)
  44 {
  45         uint64_t start;
  46         uint32_t i;
  47         uint64_t end;
  48         uint64_t sum = 0;
  49         uint64_t op_latency;
  50
  51         start = rte_rdtsc();
  52
  53         for (i = 0; i < ITERATIONS; i++) {
  54                 switch (rand_type) {
  55                 case rand_type_64:
  56                         sum += rte_rand();
  57                         break;
  58                 case rand_type_bounded_best_case:
  59                         sum += rte_rand_max(BEST_CASE_BOUND);
  60                         break;
  61                 case rand_type_bounded_worst_case:
  62                         sum += rte_rand_max(WORST_CASE_BOUND);
  63                         break;
  64                 }
  65         }
  66
  67         end = rte_rdtsc();
  68
  69         /* to avoid an optimizing compiler removing the whole loop */
  70         vsum = sum;
  71
  72         op_latency = (end - start) / ITERATIONS;
  73
  74         printf("%s: %"PRId64" TSC cycles/op\n", rand_type_desc(rand_type),
  75                op_latency);
  76 }
  77
  78 static int
  79 test_rand_perf(void)
  80 {
  81         rte_srand(42);
  82
  83         printf("Pseudo-random number generation latencies:\n");
  84
  85         test_rand_perf_type(rand_type_64);
  86         test_rand_perf_type(rand_type_bounded_best_case);
  87         test_rand_perf_type(rand_type_bounded_worst_case);
  88
  89         return 0;
  90 }
  91
  92 REGISTER_TEST_COMMAND(rand_perf_autotest, test_rand_perf);