#13304: GHC 8.0.* is slow when run on Windows 10 Ubuntu subsystem -------------------------------------+------------------------------------- Reporter: sukhmel | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: invalid | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #9706 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: new => closed * resolution: => invalid * related: => #9706 Comment: This is indeed a BashOnWindows bug. The original issue reported in comment:1 has been closed in favor of this one (https://github.com/Microsoft/BashOnWindows/issues/1671). In that thread, a BashOnWindows dev [https://github.com/Microsoft/BashOnWindows/issues/1671#issuecomment-27776485... notes]:
This is on our backlog but is unlikely to make the Creators Update. I know we're planning on looking at this soon though.
For some context, I've looked at what causes this slowdown. For some reason stack has mapped an mind-bogglingly huge region of memory (I'm talking dozens of terabytes). When we fork we walk the entire address range to set up the new process's state. We have a design that should vastly speed this up, but we're approaching "pencils down" date for Creators Update.
The "some reason" is #9706, which explains why this can't be reproduced in GHC 7.10. There's not much that GHC can do from its end (besides waiting for BashOnWindows to apply a fix), so I'm going to close this as invalid. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13304#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler