title: When profiling my fortran program, Acxtrnal.dll is the part using most of the CPU time! What is that dll.?
body: <p>Hi I am profiling with VTUNE (an intel visual studio extension) my 2D numerical model I wrote for my research, in order to speed it up a little. I already sped up my 1D model this way (i.e. identifying the "hotspot" of my model). This time though, after running the profiler I see that the most time consuming part is not a fortran subroutine I wrote (as it occured for my 1D model) but it is a dll called Acxtrnal.dll. I googled the name of this dll but I could not find better information. Does anybody know why this dll is taking so much and what it is needed for?
  thanks
  A.</p>
  
  <p>EDIT: So I was able to add download the symbols for the DLL from Microsoft website so now when debugging it shows that the CPU time is lost here. 
  NS_FaultTolerantHeap::APIHook_RtlFreeHeap. If I expand it shows (uppercase subroutines are mine):</p>
  
  <p>free&lt;-for__free_vm<br>
      for_write_int_fmt_xmit&lt;-for_write_int_fmt&lt;-LIMITERSUBR&lt;-RECMUSCL&lt;-MAIN__&lt;-main&lt;-_tmainCRTStartup&lt;-BaseThreadInitThunk&lt;-<strong>RtlUserThreadStart&lt;-<em>RtlUserThreadStart<br>
      for</em>_release_lun&lt;-for_write_int_fmt_xmit&lt;-for_write_int_fmt&lt;-LIMITERSUBR&lt;-RECMUSCL&lt;-MAIN</strong>&lt;-main&lt;-<em>tmainCRTStartup&lt;-BaseThreadInitThunk&lt;-</em>_RtlUserThreadStart&lt;-_RtlUserThreadStart</p>