I'm afraid so - I am just creating the ticket. / jost
On 07/19/2014 09:07 PM, Carter Schonwald wrote:
Wait, does that mean the corresponding constants in base for 7.8.3 are busted? On Saturday, July 19, 2014, Jost Berthold <berth...@mathematik.uni-marburg.de <mailto:berth...@mathematik.uni-marburg.de>> wrote: Message: 2 Date: Sat, 19 Jul 2014 15:00:17 +1000 From: Kyle Van Berendonck <kvanberendo...@gmail.com> To: "ghc-devs@haskell.org" <ghc-devs@haskell.org> Subject: Thread status constants Message-ID: <CAFSvR6A3maSWngY=__GJdATvGPjTAyuPokXZ5=rLtLT=ebyds...@mail.gmail.com> Content-Type: text/plain; charset="utf-8" Hi, I found these: https://github.com/ghc/ghc/__blob/__5f3c5384df59717ca8013c5df8d1f6__5692867825/includes/rts/__Constants.h#L194 <https://github.com/ghc/ghc/blob/5f3c5384df59717ca8013c5df8d1f65692867825/includes/rts/Constants.h#L194> They go only 0-14, so there's some long chains of branches and stuff in hot paths that could be cleaned up into single &-masked branches by changing these into a set of flags. And then I saw these: https://github.com/ghc/ghc/__blob/master/libraries/base/__GHC/Conc/Sync.lhs#L483 <https://github.com/ghc/ghc/blob/master/libraries/base/GHC/Conc/Sync.lhs#L483> Where does 16 and 17 come from -- I couldn't find them in the header files anywhere? Kyle Hi Kyle, I had a look at these constants just recently. About 16 and 17, see here: https://github.com/ghc/ghc/__blob/master/rts/PrimOps.cmm#__L853 <https://github.com/ghc/ghc/blob/master/rts/PrimOps.cmm#L853> About the others:The block reasons received two updates just recently. Turns out that the eventlog (GHC's post-mortem tracing for threadscope et al.) expects these states to have particular values (those in includes/rts/Constants.h, consider them a fixed ABI for the time being). See here for the story: https://ghc.haskell.org/trac/__ghc/ticket/9003 <https://ghc.haskell.org/trac/ghc/ticket/9003> NB: Darn... base still uses GHC-7.8.2 constants. Thanks for the pointer! About your proposal to use bit masks: Did you find some of those hot paths? I believe (believe, unchecked...) that there are not too many places where a complete switch over all possible reasons is done (apart from debug output maybe); the typical use is rather to compare to one single constant than to all. So the performance might not increase too much from optimisations. Again, just a hunch, not verified. If the RTS contains code specialised to the current constants, these places need to be kept symbolic, to avoid future breakage when new states are added. A fix which removes the tight implicit dependency of ghc-events from the constants in includes/rts/Constants.h is pending, btw. / Jost _________________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://www.haskell.org/__mailman/listinfo/ghc-devs <http://www.haskell.org/mailman/listinfo/ghc-devs>
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