#12455: Compact Regions -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: task | Status: new Priority: high | Milestone: 8.2.1 Component: Runtime System | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Marlow ): In [changeset:"55d535da10dd63bbaf03fb176ced7179087cd0d4/ghc" 55d535d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="55d535da10dd63bbaf03fb176ced7179087cd0d4" Remove CONSTR_STATIC Summary: We currently have two info tables for a constructor * XXX_con_info: the info table for a heap-resident instance of the constructor, It has type CONSTR, or one of the specialised types like CONSTR_1_0 * XXX_static_info: the info table for a static instance of this constructor, which has type CONSTR_STATIC or CONSTR_STATIC_NOCAF. I'm getting rid of the latter, and using the `con_info` info table for both static and dynamic constructors. For rationale and more details see Note [static constructors] in SMRep.hs. I also removed these macros: `isSTATIC()`, `ip_STATIC()`, `closure_STATIC()`, since they relied on the CONSTR/CONSTR_STATIC distinction, and anyway HEAP_ALLOCED() does the same job. Test Plan: validate Reviewers: bgamari, simonpj, austin, gcampax, hvr, niteria, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2690 GHC Trac Issues: #12455 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12455#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#12455: Compact Regions -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: task | Status: new Priority: high | Milestone: 8.2.1 Component: Runtime System | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2751 Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonmar): * differential: => Phab:D2751 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12455#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#12455: Compact Regions -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: task | Status: patch Priority: high | Milestone: 8.2.1 Component: Runtime System | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2751 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Marlow ): In [changeset:"7036fde9df61b6eae9719c7f6c656778c756bec9/ghc" 7036fde/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="7036fde9df61b6eae9719c7f6c656778c756bec9" Overhaul of Compact Regions (#12455) Summary: This commit makes various improvements and addresses some issues with Compact Regions (aka Compact Normal Forms). This was the most important thing I wanted to fix. Compaction previously prevented GC from running until it was complete, which would be a problem in a multicore setting. Now, we compact using a hand-written Cmm routine that can be interrupted at any point. When a GC is triggered during a sharing-enabled compaction, the GC has to traverse and update the hash table, so this hash table is now stored in the StgCompactNFData object. Previously, compaction consisted of a deepseq using the NFData class, followed by a traversal in C code to copy the data. This is now done in a single pass with hand-written Cmm (see rts/Compact.cmm). We no longer use the NFData instances, instead the Cmm routine evaluates components directly as it compacts. The new compaction is about 50% faster than the old one with no sharing, and a little faster on average with sharing (the cost of the hash table dominates when we're doing sharing). Static objects that don't (transitively) refer to any CAFs don't need to be copied into the compact region. In particular this means we often avoid copying Char values and small Int values, because these are static closures in the runtime. Each Compact# object can support a single compactAdd# operation at any given time, so the Data.Compact library now enforces mutual exclusion using an MVar stored in the Compact object. We now get exceptions rather than killing everything with a barf() when we encounter an object that cannot be compacted (a function, or a mutable object). We now also detect pinned objects, which can't be compacted either. The Data.Compact API has been refactored and cleaned up. A new compactSize operation returns the size (in bytes) of the compact object. Most of the documentation is in the Haddock docs for the compact library, which I've expanded and improved here. Various comments in the code have been improved, especially the main Note [Compact Normal Forms] in rts/sm/CNF.c. I've added a few tests, and expanded a few of the tests that were there. We now also run the tests with GHCi, and in a new test way that enables sanity checking (+RTS -DS). There's a benchmark in libraries/compact/tests/compact_bench.hs for measuring compaction speed and comparing sharing vs. no sharing. The field totalDataW in StgCompactNFData was unnecessary. Test Plan: * new unit tests * validate * tested manually that we can compact Data.Aeson data Reviewers: gcampax, bgamari, ezyang, austin, niteria, hvr, erikd Subscribers: thomie, simonpj Differential Revision: https://phabricator.haskell.org/D2751 GHC Trac Issues: #12455 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12455#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler