8.2 and earlier build times

[Simon Peyton Jones]

|  We'll need to look at what is going on here as this is a pretty
|  significant regression.

Make a ticket with repro instructions?

s

|  -----Original Message-----
|  From: Ben Gamari [mailto:ben at smart-cactus.org]
|  Sent: 20 May 2017 18:20
|  To: Herbert Valerio Riedel <hvriedel at gmail.com>; Simon Peyton Jones
|  <simonpj at microsoft.com>
|  Cc: ghc-devs at haskell.org
|  Subject: Re: 8.2 and earlier build times
|  
|  Ben Gamari <ben at smart-cactus.org> writes:
|  
|  snip
|  >
|  > 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.
|  >
|  >
|  I tried this again with regex-tdfa-1.2.2 and indeed I was able to
|  reproduce Herbert's result,
|  
|  
|  8.0.2
|      normal:   <<ghc: 91199006664 bytes, 3573 GCs, 260839393/610327968
|  avg/max bytes residency (30 samples), 1687M in use, 0.000 INIT (0.001
|  elapsed), 0.319 MUT (49.441 elapsed), 0.858 GC (30.681 elapsed) :ghc>>
|      profiled: <<ghc: 73210356144 bytes, 3333 GCs, 225266643/599801320
|  avg/max bytes residency (26 samples), 1731M in use, 0.000 INIT (0.001
|  elapsed), 0.352 MUT (39.318 elapsed), 0.685 GC (21.644 elapsed) :ghc>>
|  
|  8.2.1-rc2:
|      normal:   <<ghc: 90928069104 bytes, 3655 GCs, 256129517/594585536
|  avg/max bytes residency (29 samples), 1691M in use, 0.000 INIT (0.001
|  elapsed), 1.137 MUT (84.652 elapsed), 0.941 GC (47.811 elapsed) :ghc>>
|      profiled: <<ghc: 73010065480 bytes, 3228 GCs, 225992177/578697488
|  avg/max bytes residency (27 samples), 1649M in use, 0.000 INIT (0.001
|  elapsed), 0.318 MUT (53.871 elapsed), 0.728 GC (32.681 elapsed) :ghc>>
|  
|  We'll need to look at what is going on here as this is a pretty
|  significant regression.
|  
|  Cheers,
|  
|  - Ben