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[GHC] #8862: forkProcess does not play well with heap or time profiling
by GHC 08 Mar '14

08 Mar '14

#8862: forkProcess does not play well with heap or time profiling --------------------------+------------------------------------------------ Reporter: | Owner: simonmar bennofs | Status: new Type: bug | Milestone: Priority: normal | Version: 7.6.3 Component: | Operating System: Unknown/Multiple Runtime System | Type of failure: Incorrect result at runtime Keywords: | Test Case: Architecture: | Blocking: Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | --------------------------+------------------------------------------------ This is similar to #4512. When doing heap or time profiling, the forked process and the parent process both write to the same `.hp` or `.prof` file. I think this also applies to program coverage using hpc (didn't test this). I was able to reproduce the bug with the attached source code, but some other people were not. Just run `space-profiling +RTS -h` and try to convert the generated heap profile using `hp2ps`, I get the following error message: {{{ hp2ps: space-profiling.hp, line 186: integer must follow identifier }}} I attached the generated hp file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8862> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8860: Optimized Cmm isn't
by GHC 08 Mar '14

08 Mar '14

#8860: Optimized Cmm isn't ------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- The optimizer seems to miss very basic optimizations. For example, look at this segment (full source below): {{{ _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); }}} I'd expect all these temporaries (that are only used ones) to be inlined, but they are not and thus we fail to see the static arguments to the `MO_Memset` call, which leads to further missed optimizations. This used to work in the old codegen. Furthermore, there are useless basic blocks in the output: {{{ c1Cm: goto c1C4; c1C4: }}} I'd expect them to be eliminated. .dump-cmm file: {{{ ==================== Cmm produced by new codegen ==================== 2014-03-08 08:25:31.728672 UTC [section "data" { a_r1za_closure: const a_r1za_info; }, a_r1za_entry() // [] { info_tbl: [(c1Cm, label: a_r1za_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 3} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c1Cm: goto c1C4; c1C4: if ((old + 0) - <highSp> < SpLim) goto c1Cp; else goto c1Cq; c1Cq: goto c1C3; c1C3: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; goto c1Ch; c1Ch: _s1C1::P64 = _s1BY::P64; goto c1Ck; c1Ck: R1 = ()_closure+1; call (P64[(old + 8)])(R1) args: 8, res: 0, upd: 8; } }] ==================== Post control-flow optimisations ==================== 2014-03-08 08:25:31.729764 UTC {offset c1Cm: if ((old + 0) - <highSp> < SpLim) goto c1Cp; else goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; _s1C1::P64 = _s1BY::P64; R1 = ()_closure+1; call (P64[(old + 8)])(R1) args: 8, res: 0, upd: 8; } ==================== Layout Stack ==================== 2014-03-08 08:25:31.730253 UTC {offset c1Cm: goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; _s1C1::P64 = _s1BY::P64; R1 = ()_closure+1; call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } ==================== CAFEnv ==================== 2014-03-08 08:25:31.73074 UTC [(c1C8, {}), (c1C9, {}), (c1Ca, {}), (c1Cm, {}), (c1Cp, {}), (c1Cq, {}), (c1Cr, {}), (c1Cs, {})] ==================== after setInfoTableStackMap ==================== 2014-03-08 08:25:31.730895 UTC a_r1za_entry() // [] { info_tbl: [(c1Cm, label: a_r1za_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 3} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c1Cm: goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; _s1C1::P64 = _s1BY::P64; R1 = ()_closure+1; call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } } ==================== Post control-flow optimisations ==================== 2014-03-08 08:25:31.731383 UTC a_r1za_entry() // [] { info_tbl: [(c1Cm, label: a_r1za_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 3} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c1Cm: goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; _s1C1::P64 = _s1BY::P64; R1 = ()_closure+1; call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } } ==================== Post CPS Cmm ==================== 2014-03-08 08:25:31.731772 UTC [section "data" { a_r1za_closure: const a_r1za_info; }, a_r1za_entry() // [] { info_tbl: [(c1Cm, label: a_r1za_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 3} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c1Cm: goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; _s1C1::P64 = _s1BY::P64; R1 = ()_closure+1; call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } }] ==================== Output Cmm ==================== 2014-03-08 08:25:31.73228 UTC [section "data" { a_r1za_closure: const a_r1za_info; }, a_r1za_entry() // [] { info_tbl: [(c1Cm, label: a_r1za_info rep:HeapRep static { Fun {arity: 1 fun_type: ArgSpec 3} })] stack_info: arg_space: 8 updfr_space: Just 8 } {offset c1Cm: goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > HpLim) goto c1Cs; else goto c1Cr; c1Cs: HpAlloc = 152; goto c1Cp; c1Cp: R1 = a_r1za_closure; call (stg_gc_fun)(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = stg_MUT_ARR_PTRS_DIRTY_info; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: P64[_c1C7::I64] = ()_closure+1; _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; _s1BY::P64 = _s1BY::P64; _s1C1::P64 = _s1BY::P64; R1 = ()_closure+1; call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } }] }}} .dump-opt-cmm file: {{{ ==================== Optimised Cmm ==================== 2014-03-08 08:25:31.732971 UTC a_r1za_entry() // [] { [(c1Cm, a_r1za_info: const 4294967299; const 0; const 15;)] } {offset c1Cm: goto c1Cq; c1Cq: Hp = Hp + 152; if (Hp > I64[BaseReg + 856]) goto c1Cs; else goto c1Cr; c1Cs: I64[BaseReg + 904] = 152; goto c1Cp; c1Cp: R1 = PicBaseReg + a_r1za_closure; call (I64[BaseReg - 8])(R1) args: 8, res: 0, upd: 8; c1Cr: I64[Hp - 144] = I64[PicBaseReg + stg_MUT_ARR_PTRS_DIRTY_info@GOTPCREL]; I64[Hp - 136] = 16; I64[Hp - 128] = 16; _c1C6::I64 = Hp - 144; _c1C7::I64 = _c1C6::I64 + 24; goto c1C8; c1C8: if (_c1C7::I64 < (_c1C6::I64 + 128)) goto c1Ca; else goto c1C9; c1Ca: I64[_c1C7::I64] = PicBaseReg + (()_closure+1); _c1C7::I64 = _c1C7::I64 + 8; goto c1C8; c1C9: _c1Cb::I64 = _c1C6::I64 + 24; _c1Cc::I64 = _c1Cb::I64 + 128; _c1Cd::I64 = 0; _c1Ce::I64 = 0; _c1Cf::I64 = 8; call MO_Memset(_c1Cc::I64, _c1Cd::I64, _c1Ce::I64, _c1Cf::I64); _s1BY::P64 = _c1C6::I64; // nop _s1C1::P64 = _s1BY::P64; R1 = PicBaseReg + (()_closure+1); call (P64[Sp])(R1) args: 8, res: 0, upd: 8; } } }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8860> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5925: Add inline version of newArray#
by GHC 08 Mar '14

08 Mar '14

#5925: Add inline version of newArray# -------------------------------------+------------------------------------ Reporter: tibbe | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: 4258 Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by tibbe): I got this working I think, except that the Cmm optimizer does such a poor job on the Cmm I generate (which is simple) that I'm not sure if we can get anywhere here without first fixing that problem. See e.g #8860. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5925#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6018: Injective type families
by GHC 08 Mar '14

08 Mar '14

#6018: Injective type families -------------------------------+------------------------------------------- Reporter: lunaris | Owner: simonpj Type: feature | Status: new request | Milestone: 7.8.1 Priority: normal | Version: 7.4.1 Component: Compiler | Keywords: TypeFamilies, Injective Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #4259 None/Unknown | Test Case: | Blocking: | -------------------------------+------------------------------------------- Changes (by dmcclean): * cc: douglas.mcclean@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6018#comment:19> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8824: cloning from https://github.com/ghc/ghc.git is broken
by GHC 08 Mar '14

08 Mar '14

#8824: cloning from https://github.com/ghc/ghc.git is broken ------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Specifically the clone works, but then `./sync-all get` fails; {{{ Cloning into 'libraries/Cabal'... fatal: repository 'https://github.com/ghc/packages/Cabal.git/' not found Clone of 'https://github.com/ghc/packages/Cabal.git' into submodule path 'libraries/Cabal' failed }}} It was broken by b755c7bd6af9f2bee47427b1eaa6c29c72b2b17a which (around lines 587-588) assumes the protocol is `git://`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8824> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8678: Derivin `Functor` complains about existential type
by GHC 07 Mar '14

07 Mar '14

#8678: Derivin `Functor` complains about existential type ------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- When deriving a functor with !DataKinds enabled {{{ {-# LANGUAGE DataKinds, DeriveFunctor, FlexibleInstances, GADTs, KindSignatures, StandaloneDeriving #-} data {- kind -} Nat = Z | S Nat data NonStandard :: Nat -> * -> * where Standard :: a -> NonStandard (S n) a Non :: NonStandard n a -> a -> NonStandard (S n) a deriving instance Show a => Show (NonStandard n a) deriving instance Functor (NonStandard n) }}} I get following error message {{{ NonStandard.hs:10:1: Can't make a derived instance of ‛Functor (NonStandard n)’: Constructor ‛Standard’ must not have existential arguments In the stand-alone deriving instance for ‛Functor (NonStandard n)’ }}} But the `Standard` constructor is not at all existential in the last type argument! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8678> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7316: GHC segfaults on ARM
by GHC 07 Mar '14

07 Mar '14

#7316: GHC segfaults on ARM -------------------------------------+--------------------------- Reporter: laney | Owner: bgamari Type: bug | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.4.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: arm Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: 3658 Blocking: 7623 | Related Tickets: -------------------------------------+--------------------------- Changes (by bgamari): * priority: high => normal Comment: At this point it seems like dynamic linking works pretty well with the LLVM backend on ARM. We can keep this bug open as the bug likely still lurks in GHC's linker, but it's not nearly as critical now. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7316#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7651: Buiding GHC with parallel IO manager freezes on Mac (not on FreeBSD)
by GHC 07 Mar '14

07 Mar '14

#7651: Buiding GHC with parallel IO manager freezes on Mac (not on FreeBSD) ----------------------------------------+---------------------------------- Reporter: kazu-yamamoto | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Build System | Version: 7.7 Resolution: | Keywords: Operating System: MacOS X | Architecture: Type of failure: Building GHC failed | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ----------------------------------------+---------------------------------- Comment (by kazu-yamamoto): Which does "fail" mean, freeze (non stopping) or stop with an error? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7651#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7651: Buiding GHC with parallel IO manager freezes on Mac (not on FreeBSD)
by GHC 07 Mar '14

07 Mar '14

#7651: Buiding GHC with parallel IO manager freezes on Mac (not on FreeBSD) ----------------------------------------+---------------------------------- Reporter: kazu-yamamoto | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Build System | Version: 7.7 Resolution: | Keywords: Operating System: MacOS X | Architecture: Type of failure: Building GHC failed | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ----------------------------------------+---------------------------------- Comment (by George): wrt building GHC on Mac sometimes fails, see #8620, building in parallel on Mavericks is failing for some users -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7651#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5925: Add inline version of newArray#
by GHC 07 Mar '14

07 Mar '14

#5925: Add inline version of newArray# -------------------------------------+------------------------------------ Reporter: tibbe | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: 4258 Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by jberryman): Replying to [comment:12 tibbe]: > ...So the task at this point is to come up with some good benchmarks. There are essentially two ways to attack that problem. Either we can try to show a speed-up in allocation or we can try to show a speed-up due to the better locality (e.g. constructor wrapping an array can now be allocated next to the array.) I don't understand this issue very well, but I wonder if you'd see any difference in running something like this through criterion: {{{ do let payload = P.newArray 32 0 :: IO (P.MutableArray (PrimState IO) Int) x <- newEmptyMVar y <- newEmptyMVar forkIO $ (replicateM_ 500 payload) >> putMVar x () forkIO $ (replicateM_ 500 payload) >> putMVar y () -- ... etc, for number of cores - 1 or so takeMVar x takeMVar y }}} ..using `payload = return ()` as the baseline measurement? Or maybe microbenchmark newArray followed by a read? Re. better locality, I have a real application: a Chan-like IORef linked list of small `MutableArray`s. Maybe creating/traversing a structure like that would show some improvement? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5925#comment:13> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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