[GHC] #14492: Tiered memory allocation restricts available memory

[GHC]

#14492: Tiered memory allocation restricts available memory
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        Reporter:  unode             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Runtime System    |              Version:  8.0.2
      Resolution:                    |             Keywords:  memory ulimit
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Poor/confusing    |  (amd64)
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by bgamari):

 * cc: Jaffacake (added)
 * milestone:   => 8.4.1


Comment:

 > A simple solution is to replace `*len /= 2` by `*len -= *len/8`. The max
 number of calls to `mmap()` goes up from 14 to 67, but wastage is now at
 most 1/8th of the final allocated memory.

 Indeed this sounds like a pretty simple solution. I don't even think the
 increase in number of `mmap` calls is all that bad since these are failed
 `mmap`s, so they shouldn't incur the usual overhead.

 What do you think, simonmar?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14492#comment:5>
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