[GHC] #9232: Stats file has wrong numbers
#9232: Stats file has wrong numbers ------------------------------------+----------------------------- Reporter: augustss | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.8.2 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+----------------------------- The summary numbers in the file generated with the -S flag cannot be right. Here's an example: {{{ 1,943,795,468 bytes allocated in the heap 17,587,189,232 bytes copied during GC }}} The corresponding numbers with ghc 7.2 are {{{ 193,859,474,520 bytes allocated in the heap 17,766,908,288 bytes copied during GC }}} While it's theoretically possible that allocation has improved that much, I don't believe it. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9232 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9232: Stats file has wrong numbers -----------------------------------+------------------------------------ Reporter: augustss | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Windows | Architecture: Unknown/Multiple Type of failure: Other | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -----------------------------------+------------------------------------ Comment (by simonpj): Does time improve? Does allocation rate change? It's unusual, but entirely possible. Eg better let-floating or whatnot. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9232#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9232: Stats file has wrong numbers -----------------------------------+------------------------------------ Reporter: augustss | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Windows | Architecture: Unknown/Multiple Type of failure: Other | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -----------------------------------+------------------------------------ Comment (by augustss): No, the overall time is worse. And the number of garbage collections has increased. ghc 7.6: {{{ Gen 0 1389 colls, 0 par 60.28s 60.75s 0.0437s 0.6840s Gen 1 21 colls, 0 par 27.11s 27.68s 1.3182s 4.0802s }}} ghc 7.8: {{{ Gen 0 1438 colls, 0 par 58.84s 58.68s 0.0408s 0.6828s Gen 1 21 colls, 0 par 29.31s 30.59s 1.4566s 4.5564s }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9232#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9232: Stats file has wrong numbers -----------------------------------+------------------------------------ Reporter: augustss | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Windows | Architecture: Unknown/Multiple Type of failure: Other | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -----------------------------------+------------------------------------ Comment (by simonpj): OK, so the displayed allocation rate (displayed by -S) must be much, much, much lower? After all, you are saying that GHC 7.8 allocates 100x less data, but takes longer, so the allocation rate must be much lower too. Would you like to show the actual output? A useful thing to do is to compile everything (libraries and all, ideally, but not essential) with `-ticky`. That has no effect on optimisation but does gather per-function allocation counts. Then run with `+RTS -rfoo.ticky`. Results in file `foo.ticky`. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9232#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9232: Stats file has wrong numbers -----------------------------------+------------------------------------ Reporter: augustss | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Windows | Architecture: Unknown/Multiple Type of failure: Other | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -----------------------------------+------------------------------------ Comment (by simonmar): We know that this isn't happening consistently, because our allocation measurements for e.g. nofib runs aren't showing any weirdness. Which means it's something more specific. I take it you can't share the program, and don't have a smaller example that demonstrates the problem? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9232#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9232: Stats file has wrong numbers -----------------------------------+------------------------------------ Reporter: augustss | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Windows | Architecture: Unknown/Multiple Type of failure: Other | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -----------------------------------+------------------------------------ Comment (by augustss): Sorry, we can't share the program. If I have time I'll try the -ticky. I'm not very concerned about this bug, but I do keep an eye on allocation numbers when making changes. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9232#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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