[GHC] #14981: GHC parallel GC is not doing well on modern many-core machine

[GHC]

#14981: GHC parallel GC is not doing well on modern many-core machine
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           Reporter:  varosi         |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Runtime        |           Version:  8.4.1
  System                             |
           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'm testing a small ray-tracer on different many-core machines, like x64
 88 core and Aarch64 96 core (on https://packet.net). Parallel GC seems to
 have throughput problems on more than 24-32 cores.

 See this Reddit thread about -
 https://www.reddit.com/r/haskell/comments/85vwlq/our_lovely_ghc_parallel_gc_on_96_core_arm/

 There you may find .eventlog file and PNG with a screenshot.

 May be it's time to resurrect Concurrent GC project again?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14981>
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