third_party/tcmalloc/chromium/src/profiledata.cc

   1 // Copyright (c) 2007, Google Inc.
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  10 //     * Redistributions in binary form must reproduce the above
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  29 //
  30 // ---
  31 // Author: Sanjay Ghemawat
  32 //         Chris Demetriou (refactoring)
  33 //
  34 // Collect profiling data.
  35
  36 #include <config.h>
  37 #include <assert.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <errno.h>
  41 #ifdef HAVE_UNISTD_H
  42 #include <unistd.h>
  43 #endif
  44 #include <sys/time.h>
  45 #include <string.h>
  46 #include <fcntl.h>
  47
  48 #include "profiledata.h"
  49
  50 #include "base/logging.h"
  51 #include "base/sysinfo.h"
  52
  53 // All of these are initialized in profiledata.h.
  54 const int ProfileData::kMaxStackDepth;
  55 const int ProfileData::kAssociativity;
  56 const int ProfileData::kBuckets;
  57 const int ProfileData::kBufferLength;
  58
  59 ProfileData::Options::Options()
  60     : frequency_(1) {
  61 }
  62
  63 // This function is safe to call from asynchronous signals (but is not
  64 // re-entrant).  However, that's not part of its public interface.
  65 void ProfileData::Evict(const Entry& entry) {
  66   const int d = entry.depth;
  67   const int nslots = d + 2;     // Number of slots needed in eviction buffer
  68   if (num_evicted_ + nslots > kBufferLength) {
  69     FlushEvicted();
  70     assert(num_evicted_ == 0);
  71     assert(nslots <= kBufferLength);
  72   }
  73   evict_[num_evicted_++] = entry.count;
  74   evict_[num_evicted_++] = d;
  75   memcpy(&evict_[num_evicted_], entry.stack, d * sizeof(Slot));
  76   num_evicted_ += d;
  77 }
  78
  79 ProfileData::ProfileData()
  80     : hash_(0),
  81       evict_(0),
  82       num_evicted_(0),
  83       out_(-1),
  84       count_(0),
  85       evictions_(0),
  86       total_bytes_(0),
  87       fname_(0),
  88       start_time_(0) {
  89 }
  90
  91 bool ProfileData::Start(const char* fname,
  92                         const ProfileData::Options& options) {
  93   if (enabled()) {
  94     return false;
  95   }
  96
  97   // Open output file and initialize various data structures
  98   int fd = open(fname, O_CREAT | O_WRONLY | O_TRUNC, 0666);
  99   if (fd < 0) {
 100     // Can't open outfile for write
 101     return false;
 102   }
 103
 104   start_time_ = time(NULL);
 105   fname_ = strdup(fname);
 106
 107   // Reset counters
 108   num_evicted_ = 0;
 109   count_       = 0;
 110   evictions_   = 0;
 111   total_bytes_ = 0;
 112
 113   hash_ = new Bucket[kBuckets];
 114   evict_ = new Slot[kBufferLength];
 115   memset(hash_, 0, sizeof(hash_[0]) * kBuckets);
 116
 117   // Record special entries
 118   evict_[num_evicted_++] = 0;                     // count for header
 119   evict_[num_evicted_++] = 3;                     // depth for header
 120   evict_[num_evicted_++] = 0;                     // Version number
 121   CHECK_NE(0, options.frequency());
 122   int period = 1000000 / options.frequency();
 123   evict_[num_evicted_++] = period;                // Period (microseconds)
 124   evict_[num_evicted_++] = 0;                     // Padding
 125
 126   out_ = fd;
 127
 128   return true;
 129 }
 130
 131 ProfileData::~ProfileData() {
 132   Stop();
 133 }
 134
 135 // Dump /proc/maps data to fd.  Copied from heap-profile-table.cc.
 136 #define NO_INTR(fn)  do {} while ((fn) < 0 && errno == EINTR)
 137
 138 static void FDWrite(int fd, const char* buf, size_t len) {
 139   while (len > 0) {
 140     ssize_t r;
 141     NO_INTR(r = write(fd, buf, len));
 142     RAW_CHECK(r >= 0, "write failed");
 143     buf += r;
 144     len -= r;
 145   }
 146 }
 147
 148 static void DumpProcSelfMaps(int fd) {
 149   ProcMapsIterator::Buffer iterbuf;
 150   ProcMapsIterator it(0, &iterbuf);   // 0 means "current pid"
 151
 152   uint64 start, end, offset;
 153   int64 inode;
 154   char *flags, *filename;
 155   ProcMapsIterator::Buffer linebuf;
 156   while (it.Next(&start, &end, &flags, &offset, &inode, &filename)) {
 157     int written = it.FormatLine(linebuf.buf_, sizeof(linebuf.buf_),
 158                                 start, end, flags, offset, inode, filename,
 159                                 0);
 160     FDWrite(fd, linebuf.buf_, written);
 161   }
 162 }
 163
 164 void ProfileData::Stop() {
 165   if (!enabled()) {
 166     return;
 167   }
 168
 169   // Move data from hash table to eviction buffer
 170   for (int b = 0; b < kBuckets; b++) {
 171     Bucket* bucket = &hash_[b];
 172     for (int a = 0; a < kAssociativity; a++) {
 173       if (bucket->entry[a].count > 0) {
 174         Evict(bucket->entry[a]);
 175       }
 176     }
 177   }
 178
 179   if (num_evicted_ + 3 > kBufferLength) {
 180     // Ensure there is enough room for end of data marker
 181     FlushEvicted();
 182   }
 183
 184   // Write end of data marker
 185   evict_[num_evicted_++] = 0;         // count
 186   evict_[num_evicted_++] = 1;         // depth
 187   evict_[num_evicted_++] = 0;         // end of data marker
 188   FlushEvicted();
 189
 190   // Dump "/proc/self/maps" so we get list of mapped shared libraries
 191   DumpProcSelfMaps(out_);
 192
 193   Reset();
 194   fprintf(stderr, "PROFILE: interrupts/evictions/bytes = %d/%d/%" PRIuS "\n",
 195           count_, evictions_, total_bytes_);
 196 }
 197
 198 void ProfileData::Reset() {
 199   if (!enabled()) {
 200     return;
 201   }
 202
 203   // Don't reset count_, evictions_, or total_bytes_ here.  They're used
 204   // by Stop to print information about the profile after reset, and are
 205   // cleared by Start when starting a new profile.
 206   close(out_);
 207   delete[] hash_;
 208   hash_ = 0;
 209   delete[] evict_;
 210   evict_ = 0;
 211   num_evicted_ = 0;
 212   free(fname_);
 213   fname_ = 0;
 214   start_time_ = 0;
 215
 216   out_ = -1;
 217 }
 218
 219 // This function is safe to call from asynchronous signals (but is not
 220 // re-entrant).  However, that's not part of its public interface.
 221 void ProfileData::GetCurrentState(State* state) const {
 222   if (enabled()) {
 223     state->enabled = true;
 224     state->start_time = start_time_;
 225     state->samples_gathered = count_;
 226     int buf_size = sizeof(state->profile_name);
 227     strncpy(state->profile_name, fname_, buf_size);
 228     state->profile_name[buf_size-1] = '\0';
 229   } else {
 230     state->enabled = false;
 231     state->start_time = 0;
 232     state->samples_gathered = 0;
 233     state->profile_name[0] = '\0';
 234   }
 235 }
 236
 237 // This function is safe to call from asynchronous signals (but is not
 238 // re-entrant).  However, that's not part of its public interface.
 239 void ProfileData::FlushTable() {
 240   if (!enabled()) {
 241     return;
 242   }
 243
 244   // Move data from hash table to eviction buffer
 245   for (int b = 0; b < kBuckets; b++) {
 246     Bucket* bucket = &hash_[b];
 247     for (int a = 0; a < kAssociativity; a++) {
 248       if (bucket->entry[a].count > 0) {
 249         Evict(bucket->entry[a]);
 250         bucket->entry[a].depth = 0;
 251         bucket->entry[a].count = 0;
 252       }
 253     }
 254   }
 255
 256   // Write out all pending data
 257   FlushEvicted();
 258 }
 259
 260 void ProfileData::Add(int depth, const void* const* stack) {
 261   if (!enabled()) {
 262     return;
 263   }
 264
 265   if (depth > kMaxStackDepth) depth = kMaxStackDepth;
 266   RAW_CHECK(depth > 0, "ProfileData::Add depth <= 0");
 267
 268   // Make hash-value
 269   Slot h = 0;
 270   for (int i = 0; i < depth; i++) {
 271     Slot slot = reinterpret_cast<Slot>(stack[i]);
 272     h = (h << 8) | (h >> (8*(sizeof(h)-1)));
 273     h += (slot * 31) + (slot * 7) + (slot * 3);
 274   }
 275
 276   count_++;
 277
 278   // See if table already has an entry for this trace
 279   bool done = false;
 280   Bucket* bucket = &hash_[h % kBuckets];
 281   for (int a = 0; a < kAssociativity; a++) {
 282     Entry* e = &bucket->entry[a];
 283     if (e->depth == depth) {
 284       bool match = true;
 285       for (int i = 0; i < depth; i++) {
 286         if (e->stack[i] != reinterpret_cast<Slot>(stack[i])) {
 287           match = false;
 288           break;
 289         }
 290       }
 291       if (match) {
 292         e->count++;
 293         done = true;
 294         break;
 295       }
 296     }
 297   }
 298
 299   if (!done) {
 300     // Evict entry with smallest count
 301     Entry* e = &bucket->entry[0];
 302     for (int a = 1; a < kAssociativity; a++) {
 303       if (bucket->entry[a].count < e->count) {
 304         e = &bucket->entry[a];
 305       }
 306     }
 307     if (e->count > 0) {
 308       evictions_++;
 309       Evict(*e);
 310     }
 311
 312     // Use the newly evicted entry
 313     e->depth = depth;
 314     e->count = 1;
 315     for (int i = 0; i < depth; i++) {
 316       e->stack[i] = reinterpret_cast<Slot>(stack[i]);
 317     }
 318   }
 319 }
 320
 321 // This function is safe to call from asynchronous signals (but is not
 322 // re-entrant).  However, that's not part of its public interface.
 323 void ProfileData::FlushEvicted() {
 324   if (num_evicted_ > 0) {
 325     const char* buf = reinterpret_cast<char*>(evict_);
 326     size_t bytes = sizeof(evict_[0]) * num_evicted_;
 327     total_bytes_ += bytes;
 328     FDWrite(out_, buf, bytes);
 329   }
 330   num_evicted_ = 0;
 331 }