tests/test-multipath.c

   1 /*
   2  * Copyright (c) 2010, 2012, 2013, 2014 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #undef NDEBUG
  19 #include <assert.h>
  20 #include <getopt.h>
  21 #include <math.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include "flow.h"
  25 #include "multipath.h"
  26 #include "openvswitch/ofp-actions.h"
  27 #include "ovstest.h"
  28 #include "util.h"
  29
  30 static void
  31 test_multipath_main(int argc, char *argv[])
  32 {
  33     enum { MP_MAX_LINKS = 63 };
  34     struct ofpact_multipath mp;
  35     bool ok = true;
  36     char *error;
  37     int n;
  38
  39     set_program_name(argv[0]);
  40
  41     if (argc != 2) {
  42         ovs_fatal(0, "usage: %s multipath_action", program_name);
  43     }
  44
  45     error = multipath_parse(&mp, argv[1]);
  46     if (error) {
  47         ovs_fatal(0, "%s", error);
  48     }
  49
  50     for (n = 1; n <= MP_MAX_LINKS; n++) {
  51         enum { N_FLOWS = 65536 };
  52         double disruption, perfect, distribution;
  53         int histogram[MP_MAX_LINKS];
  54         double sum_dev2, stddev;
  55         int changed;
  56         int i;
  57
  58         changed = 0;
  59         memset(histogram, 0, sizeof histogram);
  60         for (i = 0; i < N_FLOWS; i++) {
  61             int old_link, new_link;
  62             struct flow_wildcards wc;
  63             struct flow flow;
  64
  65             flow_random_hash_fields(&flow);
  66
  67             mp.max_link = n - 1;
  68             multipath_execute(&mp, &flow, &wc);
  69             old_link = flow.regs[0];
  70
  71             mp.max_link = n;
  72             multipath_execute(&mp, &flow, &wc);
  73             new_link = flow.regs[0];
  74
  75             assert(old_link >= 0 && old_link < n);
  76             assert(new_link >= 0 && new_link < n + 1);
  77
  78             histogram[old_link]++;
  79             changed += old_link != new_link;
  80         }
  81
  82         sum_dev2 = 0.0;
  83         for (i = 0; i < n; i++) {
  84             double mean = (double) N_FLOWS / n;
  85             double deviation = histogram[i] - mean;
  86
  87             sum_dev2 += deviation * deviation;
  88         }
  89         stddev = sqrt(sum_dev2 / n);
  90
  91         disruption = (double) changed / N_FLOWS;
  92         perfect = 1.0 / (n + 1);
  93         distribution = stddev / ((double) N_FLOWS / n);
  94         printf("%2d -> %2d: disruption=%.2f (perfect=%.2f); "
  95                "stddev/expected=%.4f\n",
  96                n, n + 1, disruption, perfect, distribution);
  97
  98         switch (mp.algorithm) {
  99         case NX_MP_ALG_MODULO_N:
 100             if (disruption < (n < 2 ? .25 : .5)) {
 101                 fprintf(stderr, "%d -> %d: disruption=%.2f < .5\n",
 102                         n, n + 1, disruption);
 103                 ok = false;
 104             }
 105             break;
 106
 107         case NX_MP_ALG_HASH_THRESHOLD:
 108             if (disruption < .48 || disruption > .52) {
 109                 fprintf(stderr, "%d -> %d: disruption=%.2f not approximately "
 110                         ".5\n", n, n + 1, disruption);
 111                 ok = false;
 112             }
 113             break;
 114
 115         case NX_MP_ALG_ITER_HASH:
 116             if (!(n & (n - 1))) {
 117                 break;
 118             }
 119             /* Fall through. */
 120         case NX_MP_ALG_HRW:
 121             if (fabs(disruption - perfect) >= .01) {
 122                 fprintf(stderr, "%d -> %d: disruption=%.5f differs from "
 123                         "perfect=%.5f by more than .01\n",
 124                         n, n + 1, disruption, perfect);
 125                 ok = false;
 126             }
 127             break;
 128
 129         default:
 130             OVS_NOT_REACHED();
 131         }
 132     }
 133
 134     exit(ok ? 0 : 1);
 135 }
 136
 137 OVSTEST_REGISTER("test-multipath", test_multipath_main);