[GHC] #9706: New block-structured heap organization for 64-bit

[GHC]

#9706: New block-structured heap organization for 64-bit
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              Reporter:  ezyang      |            Owner:  simonmar
                  Type:  task        |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Runtime     |          Version:  7.8.3
  System                             |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by simonmar):

 Ok, so there's no problem with page tables for the reserved region on
 Linux.

 Using total memory + swap is a safe limit for the address space to
 reserve, since we never want to overcommit with actual heap memory.

 I still think we should separate this from the question of reorganising
 the block descriptors, which is probably a good idea and depends on this,
 but can be tackled separately.

 Open questions:

  * Does VirtualAlloc on Windows behave the same way?  That is, can we
 allocate as much address space as we want, without creating page tables
 and without getting an out of memory error?
  * What do we do when overcommit is disabled on Linux?
  * What about OS X?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9706#comment:13>
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