tests/test-multipath.c

   1 /*
   2  * Copyright (c) 2010, 2012 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
  19 #include "multipath.h"
  20
  21 #include <assert.h>
  22 #include <getopt.h>
  23 #include <math.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26
  27 #include "flow.h"
  28 #include "ofp-actions.h"
  29 #include "random.h"
  30 #include "util.h"
  31
  32 int
  33 main(int argc, char *argv[])
  34 {
  35     enum { MP_MAX_LINKS = 63 };
  36     struct ofpact_multipath mp;
  37     bool ok = true;
  38     int n;
  39
  40     set_program_name(argv[0]);
  41     random_init();
  42
  43     if (argc != 2) {
  44         ovs_fatal(0, "usage: %s multipath_action", program_name);
  45     }
  46
  47     multipath_parse(&mp, argv[1]);
  48     for (n = 1; n <= MP_MAX_LINKS; n++) {
  49         enum { N_FLOWS = 65536 };
  50         double disruption, perfect, distribution;
  51         int histogram[MP_MAX_LINKS];
  52         double sum_dev2, stddev;
  53         int changed;
  54         int i;
  55
  56         changed = 0;
  57         memset(histogram, 0, sizeof histogram);
  58         for (i = 0; i < N_FLOWS; i++) {
  59             int old_link, new_link;
  60             struct flow flow;
  61
  62             random_bytes(&flow, sizeof flow);
  63
  64             mp.max_link = n - 1;
  65             multipath_execute(&mp, &flow);
  66             old_link = flow.regs[0];
  67
  68             mp.max_link = n;
  69             multipath_execute(&mp, &flow);
  70             new_link = flow.regs[0];
  71
  72             assert(old_link >= 0 && old_link < n);
  73             assert(new_link >= 0 && new_link < n + 1);
  74
  75             histogram[old_link]++;
  76             changed += old_link != new_link;
  77         }
  78
  79         sum_dev2 = 0.0;
  80         for (i = 0; i < n; i++) {
  81             double mean = (double) N_FLOWS / n;
  82             double deviation = histogram[i] - mean;
  83
  84             sum_dev2 += deviation * deviation;
  85         }
  86         stddev = sqrt(sum_dev2 / n);
  87
  88         disruption = (double) changed / N_FLOWS;
  89         perfect = 1.0 / (n + 1);
  90         distribution = stddev / ((double) N_FLOWS / n);
  91         printf("%2d -> %2d: disruption=%.2f (perfect=%.2f); "
  92                "stddev/expected=%.4f\n",
  93                n, n + 1, disruption, perfect, distribution);
  94
  95         switch (mp.algorithm) {
  96         case NX_MP_ALG_MODULO_N:
  97             if (disruption < (n < 2 ? .25 : .5)) {
  98                 fprintf(stderr, "%d -> %d: disruption=%.2f < .5\n",
  99                         n, n + 1, disruption);
 100                 ok = false;
 101             }
 102             break;
 103
 104         case NX_MP_ALG_HASH_THRESHOLD:
 105             if (disruption < .48 || disruption > .52) {
 106                 fprintf(stderr, "%d -> %d: disruption=%.2f not approximately "
 107                         ".5\n", n, n + 1, disruption);
 108                 ok = false;
 109             }
 110             break;
 111
 112         case NX_MP_ALG_ITER_HASH:
 113             if (!(n & (n - 1))) {
 114                 break;
 115             }
 116             /* Fall through. */
 117         case NX_MP_ALG_HRW:
 118             if (fabs(disruption - perfect) >= .01) {
 119                 fprintf(stderr, "%d -> %d: disruption=%.5f differs from "
 120                         "perfect=%.5f by more than .01\n",
 121                         n, n + 1, disruption, perfect);
 122                 ok = false;
 123             }
 124             break;
 125
 126         default:
 127             NOT_REACHED();
 128         }
 129     }
 130
 131     return ok ? 0 : 1;
 132 }