[GHC] #15976: Can't run nofib in parallel

[GHC]

#15976: Can't run nofib in parallel
-------------------------------------+-------------------------------------
           Reporter:  sgraf          |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  ⊥
          Component:  NoFib          |           Version:
  benchmark suite                    |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 I was under the impression that `make -j$n` within `nofib` would run
 benchmarks in parallel, but it doesn't. The following warning is
 indicative:

 {{{
 make[1]: warning: -jN forced in submake: disabling jobserver mode.
 }}}

 Whenever `make` is called recursively, any `-j` flags will lead to this
 warning and consequently disable parallelisation (which would lead to a
 number of jobs exponential in the depth of recursive calls).

 Parallel benchmarks are useful to get deterministic metrics such as
 allocations or counted instructions really fast.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15976>
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