Re: [Valgrind-users] Expected slowdown

[Christoph B. <bar...@or...>]

Finally the result of opannotate on the most timeconsuming function:

               :ExeContext* VG_(record_ExeContext) ( ThreadId tid )
7296101 23.2144 :{ /* vgPlain_record_ExeContext total: 28374282 90.2800 */
               :   Int         i;
               :   Addr        ips[VG_DEEPEST_BACKTRACE];
               :   Bool        same;
               :   UWord       hash;
               :   ExeContext* new_ec;
               :   ExeContext* list;
               :   UInt        n_ips;
               :
     7 2.2e-05 :   init_ExeContext_storage();
   276 8.8e-04 :   vg_assert(VG_(clo_backtrace_size) >= 1 &&
               :             VG_(clo_backtrace_size) <= VG_DEEPEST_BACKTRACE);
               :
     61 1.9e-04 :   n_ips = VG_(get_StackTrace) (tid, ips 
VG_(clo_backtrace_size) );
   104 3.3e-04 :   tl_assert(n_ips >= 1);
               :
               :   /* Now figure out if we've seen this one before.  First 
hash it so
               :      as to determine the list number. */
               :
               :   hash = 0;
   333  0.0011 :   for (i = 0; i < n_ips; i++) {
   541  0.0017 :      hash ^= ips[i];
   225 7.2e-04 :      hash = (hash << 29) | (hash >> 3);
               :   }
   171 5.4e-04 :   hash = hash % N_EC_LISTS;
               :
               :   /* And (the expensive bit) look a matching entry in the 
list. */
               :
               :   ec_searchreqs++;
               :
     2 6.4e-06 :   list = ec_list[hash];
               :
               :   while (True) {
688333  2.1901 :      if (list == NULL) break;
               :      ec_searchcmps++;
               :      same = True;
6002376 19.0981 :      for (i = 0; i < n_ips; i++) {
11124624 35.3958 :         if (list->ips[i] != ips[i]) {
               :            same = False;
               :            break;
               :         }
               :      }
               :      if (same) break;
3260252 10.3733 :      list = list->next;
               :   }
               :
    15 4.8e-05 :   if (list != NULL) {
               :      /* Yay!  We found it.  */
               :      return list;
               :   }
               :
               :   /* Bummer.  We have to allocate a new context record. */
               :   ec_totstored++;
               :
               :   new_ec = VG_(arena_malloc)( VG_AR_EXECTXT,
               :                               sizeof(struct _ExeContext)
               :                               + n_ips * sizeof(Addr) );
               :
               :   for (i = 0; i < n_ips; i++)
               :      new_ec->ips[i] = ips[i];
               :
               :   new_ec->n_ips = n_ips;
               :   new_ec->next  = ec_list[hash];
   818  0.0026 :   ec_list[hash] = new_ec;
               :
               :   return new_ec;
    43 1.4e-04 :}