[GHC] #10455: No detail for profiling costs atributed to SYSTEM / PINNED / ARR_WORDS

[GHC]

#10455: No detail for profiling costs atributed to SYSTEM / PINNED / ARR_WORDS
-------------------------------------+-------------------------------------
              Reporter:  duncan      |             Owner:
                  Type:  feature     |            Status:  new
  request                            |         Milestone:
              Priority:  normal      |           Version:  7.10.1
             Component:  Profiling   |  Operating System:  Unknown/Multiple
              Keywords:              |   Type of failure:  Other
          Architecture:              |        Blocked By:
  Unknown/Multiple                   |   Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------
 When using ghc's heap profiling, some allocations are treated specially in
 such a way that we get no useful information for them.

  * For +RTS -hc "cost centre stack", the allocations are classed as
 PINNED, which means we cannot see which cost centre allocated them.

  * For +RTS -hm "module", the allocations are classed as SYSTEM, which
 means we cannot see which module allocated them.

  * For +RTS -hy "type description" and +RTS -hd "closure description", the
 allocations are classed as ARR_WORDS, which means we cannot see what type
 they are (ByteArray#?).

 So none of these modes help us see what these allocations are or where
 they come from. Do these allocations have to be treated in this special
 way such that we loose all useful information?

 Presumably they are pinned ByteArray#s, but surely we can still track
 which cost centre to assign them to, and hence the module, and shouldn't
 the type/closure description be "ByteArray#" or "pinned ByteArray#" or
 something?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10455>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler