2 * Copyright (c) 2010, 2012, 2013 Nicira, Inc.
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:
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 #include "multipath.h"
28 #include "ofp-actions.h"
33 main(int argc, char *argv[])
35 enum { MP_MAX_LINKS = 63 };
36 struct ofpact_multipath mp;
41 set_program_name(argv[0]);
45 ovs_fatal(0, "usage: %s multipath_action", program_name);
48 error = multipath_parse(&mp, argv[1]);
50 ovs_fatal(0, "%s", error);
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;
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;
68 random_bytes(&flow, sizeof flow);
71 multipath_execute(&mp, &flow, &wc);
72 old_link = flow.regs[0];
75 multipath_execute(&mp, &flow, &wc);
76 new_link = flow.regs[0];
78 assert(old_link >= 0 && old_link < n);
79 assert(new_link >= 0 && new_link < n + 1);
81 histogram[old_link]++;
82 changed += old_link != new_link;
86 for (i = 0; i < n; i++) {
87 double mean = (double) N_FLOWS / n;
88 double deviation = histogram[i] - mean;
90 sum_dev2 += deviation * deviation;
92 stddev = sqrt(sum_dev2 / n);
94 disruption = (double) changed / N_FLOWS;
95 perfect = 1.0 / (n + 1);
96 distribution = stddev / ((double) N_FLOWS / n);
97 printf("%2d -> %2d: disruption=%.2f (perfect=%.2f); "
98 "stddev/expected=%.4f\n",
99 n, n + 1, disruption, perfect, distribution);
101 switch (mp.algorithm) {
102 case NX_MP_ALG_MODULO_N:
103 if (disruption < (n < 2 ? .25 : .5)) {
104 fprintf(stderr, "%d -> %d: disruption=%.2f < .5\n",
105 n, n + 1, disruption);
110 case NX_MP_ALG_HASH_THRESHOLD:
111 if (disruption < .48 || disruption > .52) {
112 fprintf(stderr, "%d -> %d: disruption=%.2f not approximately "
113 ".5\n", n, n + 1, disruption);
118 case NX_MP_ALG_ITER_HASH:
119 if (!(n & (n - 1))) {
124 if (fabs(disruption - perfect) >= .01) {
125 fprintf(stderr, "%d -> %d: disruption=%.5f differs from "
126 "perfect=%.5f by more than .01\n",
127 n, n + 1, disruption, perfect);