Hm... not exactly the bug disappear, you observed no speedup with "binary packed" version in the first place. Notice that in my benchmark,
In your case, there was no speed-up in the first place. May I ask you to check also `stack exec performance-bug-pair-2` and `stack exec
#14980: Runtime performance regression with binary operations on vectors -------------------------------------+------------------------------------- Reporter: ttylec | Owner: bgamari Type: bug | Status: new Priority: high | Milestone: 8.8.1 Component: Compiler | Version: 8.2.2 Resolution: | Keywords: vector | bitwise operations Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): Replying to [comment:7 ttylec]: the "binary packed" version is an order of magnitude faster that the "unbox vectors" and the bug is about loosing that speed-up when we compile with 8.2.2 (and later) Indeed, I noticed. performance-bug-2`? Stack failed on a cassava thing, I'm not exactly sure how to fix it, so I tried cabal first. If stack vs. cabal is the problem, however, then most likely that means it's a library problem rather than a GHC bug. I'll see if I can sort it out though, so that maybe I can reproduce your results. However, I don't think optimization settings could be the problem - after all, these are specified in the .cabal file, not stack.yaml, I have not overridden anything, and I verified that -O2 actually gets passed to GHC. I have even compiled the programs manually, merely pointing GHC to the cabal sandbox's package cache, and got the same results regardless. Results for `performance-bug-2` are similar. 8.0.2: {{{ "Generated" benchmarking 64 columns/raw unbox vectors time 445.2 μs (445.1 μs .. 445.4 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 443.4 μs (442.9 μs .. 443.8 μs) std dev 1.366 μs (1.077 μs .. 1.655 μs) benchmarking 64 columns/binary packed time 51.16 μs (51.09 μs .. 51.24 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 50.95 μs (50.90 μs .. 51.01 μs) std dev 204.4 ns (159.7 ns .. 264.0 ns) benchmarking 256 columns/raw unbox vectors time 443.9 μs (443.6 μs .. 444.4 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 442.7 μs (442.1 μs .. 444.1 μs) std dev 2.711 μs (1.414 μs .. 5.048 μs) benchmarking 256 columns/binary packed time 260.4 μs (255.3 μs .. 266.2 μs) 0.997 R² (0.996 R² .. 0.998 R²) mean 266.6 μs (263.1 μs .. 271.5 μs) std dev 9.366 μs (6.649 μs .. 13.29 μs) variance introduced by outliers: 24% (moderately inflated) }}} 8.2.2: {{{ "Generated" benchmarking 64 columns/raw unbox vectors time 445.0 μs (444.7 μs .. 445.2 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 444.0 μs (443.2 μs .. 447.0 μs) std dev 4.654 μs (1.118 μs .. 9.693 μs) benchmarking 64 columns/binary packed time 51.13 μs (51.11 μs .. 51.15 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 50.90 μs (50.86 μs .. 50.94 μs) std dev 146.1 ns (122.9 ns .. 181.2 ns) benchmarking 256 columns/raw unbox vectors time 440.4 μs (440.1 μs .. 440.5 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 437.9 μs (437.3 μs .. 438.4 μs) std dev 1.797 μs (1.576 μs .. 2.095 μs) benchmarking 256 columns/binary packed time 289.5 μs (285.1 μs .. 294.3 μs) 0.998 R² (0.998 R² .. 0.999 R²) mean 295.6 μs (292.0 μs .. 299.8 μs) std dev 8.814 μs (6.656 μs .. 11.69 μs) variance introduced by outliers: 19% (moderately inflated) }}}
I am curious on what machine/system you did tested it? Oh, and obviously optimization must be enabled (in case you didn't `stack build` it).
Debian 9, x86_64. Intel i5 CPU, 4 GB RAM, official GHC release builds. I have a few possible explanations as to why we're seeing these differences: - Stack may be pulling in other GHC versions than the release bundles - Stack may be pulling in different version of some crucial library - Whatever platform you run on might trigger different code paths in GHC I'll investigate further. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14980#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler