[GHC] #13944: Introduce synchronized FFI

[GHC]

#13944: Introduce synchronized FFI
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        Reporter:  winter            |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 > Yes, i mean all the thread pause stuff. I want to understand what is the
 minimum preparation before we can make FFI calls which doesn't get in GC's
 way. I believe this helps to reduce GC pause.

 I don't believe there is anything that we do currently that can simply be
 omitted without careful consideration at very least.

 Have you confirmed that `safe` is really as slow as you think it is? I
 think that we should better characterise the problem before we begin
 discussing possible solutions. I think it would be helpful if you had a
 benchmark and could use it answer a few questions,

  a. What overhead is incurred by a `unsafe` call?
  b. What overhead is incurred by a `safe` call?
  c. Where specifically is the additional overhead of the `safe` call
 coming from?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13944#comment:10>
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