Herbert Valerio Riedel <hvriedel@gmail.com> writes:
On Wed, May 17, 2017 at 10:56 AM, Simon Peyton Jones via ghc-devs <ghc-devs@haskell.org> wrote:
That's great news! Faster than GHC 7.8! We should advertise this :-).
However, not everything is back to 7.8 levels when looking at the time-dimension, e.g. for regex-tdfa-1.2.2 (with reasonably similar versions of dependencies):
Interesting. I tried comparing build times of regex-tdfa-1.1.8 with GHC 8.0.2 and 8.2.1, yet was unable to reproduce this. Rather 8.2 was significantly faster than 8.0.2 (although not in the profiled build, it seems), 8.0.2: real 2m4.403s user 0m2.233s sys 4m49.319s normal build: <<ghc: 91089022760 bytes, 3544 GCs, 254983314/623313256 avg/max bytes residency (29 samples), 1777M in use, 0.000 INIT (0.001 elapsed), 0.277 MUT (49.941 elapsed), 0.972 GC (28.395 elapsed) :ghc>> profiled build: <<ghc: 53822322480 bytes, 2813 GCs, 152915198/391707624 avg/max bytes residency (24 samples), 1059M in use, 0.000 INIT (0.000 elapsed), 0.177 MUT (29.445 elapsed), 0.527 GC (15.834 elapsed) :ghc>> 8.2.1-rc2: real 1m37.004s user 0m1.690s sys 4m22.921s normal build: <<ghc: 74407995376 bytes, 2547 GCs, 188938069/574558856 avg/max bytes residency (29 samples), 1524M in use, 0.001 INIT (0.001 elapsed), 66.810 MUT (33.696 elapsed), 79.093 GC (21.746 elapsed) :ghc>> profiled build: <<ghc: 55111218888 bytes, 2272 GCs, 149652372/540904144 avg/max bytes residency (26 samples), 1336M in use, 0.001 INIT (0.001 elapsed), 51.072 MUT (25.140 elapsed), 58.298 GC (16.143 elapsed) :ghc>> My methodology was roughly, $ cabal unpack regex-tdfa-1.1.8 $ cd regex-tdfa-1.1.8 $ use_component ghc 8.0.2 $ cabal configure ; time cabal build --ghc-options='-fforce-recomp -v +RTS -t -RTS' >| 8.0.2 2>&1 $ use_component ghc 8.2.1-rc2 $ cabal configure ; time cabal build --ghc-options='-fforce-recomp -v +RTS -t -RTS' >| 8.2.1 2>&1 The "normal" and "profiled" build metrics are the +RTS -t lines extract from Cabal's profiled and unprofiled GHC invocations. I believe the RTS timings for 8.0.2 are broken due to a (fixed) RTS bug, although I can't come up with a reference at the moment. Herbert, did these timings come from a VPS? Cheers, - Ben