[GHC] #750: Set -M and -c values based on available virtual memory

[GHC]

#750: Set -M and -c values based on available virtual memory
-----------------------------+----------------------------------------------
 Reporter:  simonmar         |          Owner:             
     Type:  feature request  |         Status:  new        
 Priority:  normal           |      Milestone:  _|_        
Component:  Runtime System   |        Version:  6.4.1      
 Severity:  normal           |     Resolution:             
 Keywords:                   |     Difficulty:  Easy (1 hr)
 Testcase:  N/A              |   Architecture:  Unknown    
       Os:  Unknown          |  
-----------------------------+----------------------------------------------
Changes (by igloo):

  * summary:  Set -M value based on available virtual memory => Set -M and
              -c values based on available virtual memory

Old description:

> From John Meacham:
>
>   perhaps if -M is not otherwise set, {{{getrlimit(RLIMIT_AS,..)}}} could
> be
>   called and the maximum heap size set to just under that, since it is
> the
>   point that the OS will forcefully kill the program anyway.

New description:

 From John Meacham:

   perhaps if `-M` is not otherwise set, {{{getrlimit(RLIMIT_AS,..)}}}
 could be
   called and the maximum heap size set to just under that, since it is the
   point that the OS will forcefully kill the program anyway.

 Ravi Nanavati would like to be able to set the value to a percentage of
 physical RAM, e.g. `prog +RTS -H256m -M95% -RTS'.

 Bulat Ziganshin would like to be able to do the same with `-c`.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/750>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler