#11285: Static linking is really slow sometimes -------------------------------------+------------------------------------- Reporter: ezyang | 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: -------------------------------------+------------------------------------- I'm testing on Cabal `Setup.hs`, which links against Cabal. On a beefy machine with many cores and lots of RAM, I see a x2 regression in linking time from GHC 7.10.2 to GHC 8.0 (a recent HEAD) using GNU ld (not gold): {{{ [ezyang@hs01 ezyang]$ rm A; time ghc --make A.hs -fforce-recomp [1 of 1] Compiling Main ( A.hs, A.o ) Linking A ... real 0m1.273s user 0m0.990s sys 0m0.210s [ezyang@hs01 ezyang]$ rm A; time ghc-8.0/usr/bin/ghc --make A.hs -fforce- recomp [1 of 1] Compiling Main ( A.hs, A.o ) Linking A ... real 0m3.270s user 0m2.727s sys 0m0.523s }}} On a puny eight year-old laptop, I see a x2 regression from 7.6 to 7.10 (with not much change with 8.0) {{{ ezyang@sabre:~$ rm A; time ghc --make -O0 A.hs -fforce-recomp rm: cannot remove ‘A’: No such file or directory [1 of 1] Compiling Main ( A.hs, A.o ) Linking A ... real 0m3.058s user 0m1.860s sys 0m1.164s ezyang@sabre:~$ rm A; time ghc-7.10 --make -O0 A.hs -fforce-recomp [1 of 1] Compiling Main ( A.hs, A.o ) Linking A ... real 0m7.139s user 0m4.616s sys 0m2.488s }}} There must be something which is causing the linker to run slowly in one case, and quickly in the other. It would be really good to figure out what this is. Slow linking is NOT NICE. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11285 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler