[GHC] #12032: Performance regression with large numbers of equation-style decls
#12032: Performance regression with large numbers of equation-style decls -------------------------------------+------------------------------------- Reporter: tommd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 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: -------------------------------------+------------------------------------- See the attached for a slice of code taken from Crypto-API that demonstrates a 2x regression in GHC compile times using -O2 (from 6.12.x to 7.10.x). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12032 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12032: Performance regression with large numbers of equation-style decls -------------------------------------+------------------------------------- Reporter: tommd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by tommd): * Attachment "regression-cpoly.hs" added. A slice of crypto-api that shows performance regression in GHC -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12032 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12032: Performance regression with large numbers of equation-style decls -------------------------------------+------------------------------------- Reporter: tommd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * failure: None/Unknown => Compile-time performance bug -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12032#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12032: Performance regression with large numbers of equation-style decls -------------------------------------+------------------------------------- Reporter: tommd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tommd): Things have improves since 7.10.x but are still behind 6.12.x: {{{ vagrant@debian-jessie:~$ time ghc-6.12.3 -O2 -c -fforce-recomp regression- cpoly.hs real 0m0.069s user 0m0.056s sys 0m0.004s vagrant@debian-jessie:~$ time ghc-7.10.3 -O2 -c -fforce-recomp regression- cpoly.hs real 0m0.498s user 0m0.160s sys 0m0.064s vagrant@debian-jessie:~$ time ghc-8.0.0.20160204 -O2 -c -fforce-recomp regression-cpoly.hs real 0m0.225s user 0m0.196s sys 0m0.028s }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12032#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12032: Performance regression with large numbers of equation-style decls -------------------------------------+------------------------------------- Reporter: tommd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): It looks like things initially regressed in 7.8, got much worse in 7.10, then recovered a bit in 8.0. Perhaps unsurprisingly most of the time is spent in renaming and typechecking on 8.0.1. Unfortunately, compile times are very short so it is very difficult to do reliable measurements. My suspicion here is that we have a constant factor regression which will be rather tricky to track down. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12032#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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