tests/test-multipath.c

   1 /*
   2  * Copyright (c) 2010, 2012, 2013 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     char *error;
  39     int n;
  40
  41     set_program_name(argv[0]);
  42     random_init();
  43
  44     if (argc != 2) {
  45         ovs_fatal(0, "usage: %s multipath_action", program_name);
  46     }
  47
  48     error = multipath_parse(&mp, argv[1]);
  49     if (error) {
  50         ovs_fatal(0, "%s", error);
  51     }
  52
  53     for (n = 1; n <= MP_MAX_LINKS; n++) {
  54         enum { N_FLOWS = 65536 };
  55         double disruption, perfect, distribution;
  56         int histogram[MP_MAX_LINKS];
  57         double sum_dev2, stddev;
  58         int changed;
  59         int i;
  60
  61         changed = 0;
  62         memset(histogram, 0, sizeof histogram);
  63         for (i = 0; i < N_FLOWS; i++) {
  64             int old_link, new_link;
  65             struct flow_wildcards wc;
  66             struct flow flow;
  67
  68             random_bytes(&flow, sizeof flow);
  69             memset(flow.zeros, 0, sizeof flow.zeros);
  70             flow.mpls_depth = 0;
  71
  72             mp.max_link = n - 1;
  73             multipath_execute(&mp, &flow, &wc);
  74             old_link = flow.regs[0];
  75
  76             mp.max_link = n;
  77             multipath_execute(&mp, &flow, &wc);
  78             new_link = flow.regs[0];
  79
  80             assert(old_link >= 0 && old_link < n);
  81             assert(new_link >= 0 && new_link < n + 1);
  82
  83             histogram[old_link]++;
  84             changed += old_link != new_link;
  85         }
  86
  87         sum_dev2 = 0.0;
  88         for (i = 0; i < n; i++) {
  89             double mean = (double) N_FLOWS / n;
  90             double deviation = histogram[i] - mean;
  91
  92             sum_dev2 += deviation * deviation;
  93         }
  94         stddev = sqrt(sum_dev2 / n);
  95
  96         disruption = (double) changed / N_FLOWS;
  97         perfect = 1.0 / (n + 1);
  98         distribution = stddev / ((double) N_FLOWS / n);
  99         printf("%2d -> %2d: disruption=%.2f (perfect=%.2f); "
 100                "stddev/expected=%.4f\n",
 101                n, n + 1, disruption, perfect, distribution);
 102
 103         switch (mp.algorithm) {
 104         case NX_MP_ALG_MODULO_N:
 105             if (disruption < (n < 2 ? .25 : .5)) {
 106                 fprintf(stderr, "%d -> %d: disruption=%.2f < .5\n",
 107                         n, n + 1, disruption);
 108                 ok = false;
 109             }
 110             break;
 111
 112         case NX_MP_ALG_HASH_THRESHOLD:
 113             if (disruption < .48 || disruption > .52) {
 114                 fprintf(stderr, "%d -> %d: disruption=%.2f not approximately "
 115                         ".5\n", n, n + 1, disruption);
 116                 ok = false;
 117             }
 118             break;
 119
 120         case NX_MP_ALG_ITER_HASH:
 121             if (!(n & (n - 1))) {
 122                 break;
 123             }
 124             /* Fall through. */
 125         case NX_MP_ALG_HRW:
 126             if (fabs(disruption - perfect) >= .01) {
 127                 fprintf(stderr, "%d -> %d: disruption=%.5f differs from "
 128                         "perfect=%.5f by more than .01\n",
 129                         n, n + 1, disruption, perfect);
 130                 ok = false;
 131             }
 132             break;
 133
 134         default:
 135             NOT_REACHED();
 136         }
 137     }
 138
 139     return ok ? 0 : 1;
 140 }