lib/coverage.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 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 #include "coverage.h"
  19 #include <inttypes.h>
  20 #include <stdlib.h>
  21 #include "dynamic-string.h"
  22 #include "hash.h"
  23 #include "svec.h"
  24 #include "timeval.h"
  25 #include "unixctl.h"
  26 #include "util.h"
  27 #include "vlog.h"
  28
  29 VLOG_DEFINE_THIS_MODULE(coverage);
  30
  31 /* The coverage counters. */
  32 #if USE_LINKER_SECTIONS
  33 extern struct coverage_counter *__start_coverage[];
  34 extern struct coverage_counter *__stop_coverage[];
  35 #define coverage_counters __start_coverage
  36 #define n_coverage_counters  (__stop_coverage - __start_coverage)
  37 #else  /* !USE_LINKER_SECTIONS */
  38 #define COVERAGE_COUNTER(COUNTER)                                       \
  39         DECLARE_EXTERN_PER_THREAD_DATA(unsigned int,                    \
  40                                        counter_##COUNTER);              \
  41         DEFINE_EXTERN_PER_THREAD_DATA(counter_##COUNTER, 0);            \
  42         static unsigned int COUNTER##_count(void)                       \
  43         {                                                               \
  44             unsigned int *countp = counter_##COUNTER##_get();           \
  45             unsigned int count = *countp;                               \
  46             *countp = 0;                                                \
  47             return count;                                               \
  48         }                                                               \
  49         extern struct coverage_counter counter_##COUNTER;               \
  50         struct coverage_counter counter_##COUNTER                       \
  51             = { #COUNTER, COUNTER##_count, 0 };
  52 #include "coverage.def"
  53 #undef COVERAGE_COUNTER
  54
  55 extern struct coverage_counter *coverage_counters[];
  56 struct coverage_counter *coverage_counters[] = {
  57 #define COVERAGE_COUNTER(NAME) &counter_##NAME,
  58 #include "coverage.def"
  59 #undef COVERAGE_COUNTER
  60 };
  61 #define n_coverage_counters ARRAY_SIZE(coverage_counters)
  62 #endif  /* !USE_LINKER_SECTIONS */
  63
  64 static struct ovs_mutex coverage_mutex = OVS_MUTEX_INITIALIZER;
  65
  66 static void coverage_read(struct svec *);
  67
  68 static void
  69 coverage_unixctl_show(struct unixctl_conn *conn, int argc OVS_UNUSED,
  70                      const char *argv[] OVS_UNUSED, void *aux OVS_UNUSED)
  71 {
  72     struct svec lines;
  73     char *reply;
  74
  75     svec_init(&lines);
  76     coverage_read(&lines);
  77     reply = svec_join(&lines, "\n", "\n");
  78     unixctl_command_reply(conn, reply);
  79     free(reply);
  80     svec_destroy(&lines);
  81 }
  82
  83 void
  84 coverage_init(void)
  85 {
  86     unixctl_command_register("coverage/show", "", 0, 0,
  87                              coverage_unixctl_show, NULL);
  88 }
  89
  90 /* Sorts coverage counters in descending order by total, within equal
  91  * totals alphabetically by name. */
  92 static int
  93 compare_coverage_counters(const void *a_, const void *b_)
  94 {
  95     const struct coverage_counter *const *ap = a_;
  96     const struct coverage_counter *const *bp = b_;
  97     const struct coverage_counter *a = *ap;
  98     const struct coverage_counter *b = *bp;
  99     if (a->total != b->total) {
 100         return a->total < b->total ? 1 : -1;
 101     } else {
 102         return strcmp(a->name, b->name);
 103     }
 104 }
 105
 106 static uint32_t
 107 coverage_hash(void)
 108 {
 109     struct coverage_counter **c;
 110     uint32_t hash = 0;
 111     int n_groups, i;
 112
 113     /* Sort coverage counters into groups with equal totals. */
 114     c = xmalloc(n_coverage_counters * sizeof *c);
 115     ovs_mutex_lock(&coverage_mutex);
 116     for (i = 0; i < n_coverage_counters; i++) {
 117         c[i] = coverage_counters[i];
 118     }
 119     ovs_mutex_unlock(&coverage_mutex);
 120     qsort(c, n_coverage_counters, sizeof *c, compare_coverage_counters);
 121
 122     /* Hash the names in each group along with the rank. */
 123     n_groups = 0;
 124     for (i = 0; i < n_coverage_counters; ) {
 125         int j;
 126
 127         if (!c[i]->total) {
 128             break;
 129         }
 130         n_groups++;
 131         hash = hash_int(i, hash);
 132         for (j = i; j < n_coverage_counters; j++) {
 133             if (c[j]->total != c[i]->total) {
 134                 break;
 135             }
 136             hash = hash_string(c[j]->name, hash);
 137         }
 138         i = j;
 139     }
 140
 141     free(c);
 142
 143     return hash_int(n_groups, hash);
 144 }
 145
 146 static bool
 147 coverage_hit(uint32_t hash)
 148 {
 149     enum { HIT_BITS = 1024, BITS_PER_WORD = 32 };
 150     static uint32_t hit[HIT_BITS / BITS_PER_WORD];
 151     BUILD_ASSERT_DECL(IS_POW2(HIT_BITS));
 152
 153     static long long int next_clear = LLONG_MIN;
 154
 155     unsigned int bit_index = hash & (HIT_BITS - 1);
 156     unsigned int word_index = bit_index / BITS_PER_WORD;
 157     unsigned int word_mask = 1u << (bit_index % BITS_PER_WORD);
 158
 159     /* Expire coverage hash suppression once a day. */
 160     if (time_msec() >= next_clear) {
 161         memset(hit, 0, sizeof hit);
 162         next_clear = time_msec() + 60 * 60 * 24 * 1000LL;
 163     }
 164
 165     if (hit[word_index] & word_mask) {
 166         return true;
 167     } else {
 168         hit[word_index] |= word_mask;
 169         return false;
 170     }
 171 }
 172
 173 /* Logs the coverage counters, unless a similar set of events has already been
 174  * logged.
 175  *
 176  * This function logs at log level VLL_INFO.  Use care before adjusting this
 177  * level, because depending on its configuration, syslogd can write changes
 178  * synchronously, which can cause the coverage messages to take several seconds
 179  * to write. */
 180 void
 181 coverage_log(void)
 182 {
 183     static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 3);
 184
 185     if (!VLOG_DROP_INFO(&rl)) {
 186         uint32_t hash = coverage_hash();
 187         if (coverage_hit(hash)) {
 188             VLOG_INFO("Skipping details of duplicate event coverage for "
 189                       "hash=%08"PRIx32, hash);
 190         } else {
 191             struct svec lines;
 192             const char *line;
 193             size_t i;
 194
 195             svec_init(&lines);
 196             coverage_read(&lines);
 197             SVEC_FOR_EACH (i, line, &lines) {
 198                 VLOG_INFO("%s", line);
 199             }
 200             svec_destroy(&lines);
 201         }
 202     }
 203 }
 204
 205 /* Adds coverage counter information to 'lines'. */
 206 static void
 207 coverage_read(struct svec *lines)
 208 {
 209     unsigned long long int *totals;
 210     size_t n_never_hit;
 211     uint32_t hash;
 212     size_t i;
 213
 214     hash = coverage_hash();
 215
 216     n_never_hit = 0;
 217     svec_add_nocopy(lines,
 218                     xasprintf("Event coverage, hash=%08"PRIx32":", hash));
 219
 220     totals = xmalloc(n_coverage_counters * sizeof *totals);
 221     ovs_mutex_lock(&coverage_mutex);
 222     for (i = 0; i < n_coverage_counters; i++) {
 223         totals[i] = coverage_counters[i]->total;
 224     }
 225     ovs_mutex_unlock(&coverage_mutex);
 226
 227     for (i = 0; i < n_coverage_counters; i++) {
 228         if (totals[i]) {
 229             svec_add_nocopy(lines, xasprintf("%-24s %9llu",
 230                                              coverage_counters[i]->name,
 231                                              totals[i]));
 232         } else {
 233             n_never_hit++;
 234         }
 235     }
 236     svec_add_nocopy(lines, xasprintf("%zu events never hit", n_never_hit));
 237     free(totals);
 238 }
 239
 240 void
 241 coverage_clear(void)
 242 {
 243     size_t i;
 244
 245     ovs_mutex_lock(&coverage_mutex);
 246     for (i = 0; i < n_coverage_counters; i++) {
 247         struct coverage_counter *c = coverage_counters[i];
 248         c->total += c->count();
 249     }
 250     ovs_mutex_unlock(&coverage_mutex);
 251 }