#14545: -prof causes -N to default to 1 -------------------------------------+------------------------------------- Reporter: gelisam | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: MacOS X | Architecture: x86_64 Type of failure: Incorrect result | (amd64) at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by gelisam: Old description:

Given a simple test program which prints `getNumCapabilities`:

{{{#!hs import Control.Concurrent

main :: IO () main = print =<< getNumCapabilities }}}

Compiling this with `-threaded` and running the program with `+RTS -N` is supposed to set the number of capabilities to the number of cores on the machine. This normally prints 8 on my machine:

{{{#!bash $ rm -rf Main Main.hi Main.o && ghc -threaded Main.hs && ./Main +RTS -N [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... 8 }}}

But when I compile with `-prof`, it prints 1 instead! Expected output: still 8.

{{{#!bash $ rm -rf Main Main.hi Main.o && ghc -prof -threaded Main.hs && ./Main +RTS -N [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... 1 }}}

If I use `+RTS -N8` instead, it prints 8 as expected.

Reproduced with GHC 8.0.2 and GHC 8.8.2.

New description: Given a simple test program which prints `getNumCapabilities`: {{{#!hs import Control.Concurrent main :: IO () main = print =<< getNumCapabilities }}} Compiling this with `-threaded` and running the program with `+RTS -N` is supposed to set the number of capabilities to the number of cores on the machine. This normally prints 8 on my machine: {{{#!bash $ rm -rf Main Main.hi Main.o && ghc -threaded Main.hs && ./Main +RTS -N [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... 8 }}} But when I compile with `-prof`, it prints 1 instead! Expected output: still 8. {{{#!bash $ rm -rf Main Main.hi Main.o && ghc -prof -threaded Main.hs && ./Main +RTS -N [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... 1 }}} If I use `+RTS -N8` instead, it prints 8 as expected. Reproduced with GHC 8.0.2 and GHC 8.2.2. -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14545#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#14545: -prof causes -N to default to 1 -------------------------------------+------------------------------------- Reporter: gelisam | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: MacOS X | Architecture: x86_64 Type of failure: Incorrect result | (amd64) at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4245 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"4bfff7a507b5807736e9c6ce9814a9cfa60faeff/ghc" 4bfff7a/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="4bfff7a507b5807736e9c6ce9814a9cfa60faeff" rts: Don't default to single capability when profiled This was presumably a vestige of the days when the profiled RTS couldn't run threaded. Fixes #14545. Test Plan: simonmar Reviewers: erikd, simonmar Reviewed By: simonmar Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14545 Differential Revision: https://phabricator.haskell.org/D4245 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14545#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler