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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_wildcards wc;
61 struct flow flow;
62
63 random_bytes(&flow, sizeof flow);
64 memset(flow.zeros, 0, sizeof flow.zeros);
65 flow.mpls_depth = 0;
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 NOT_REACHED();
131 }
132 }
133
134 return ok ? 0 : 1;
135 }