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Simon Marlow authored
Summary: Visible API changes: * The C struct `GCDetails` gives the stats about a single GC. This is passed to the `gcDone()` callback if one is set via the RtsConfig. (previously we just passed a collection of values, so this is more extensible, at the expense of breaking the existing API) * `RTSStats` gives cumulative stats since the start of the program, and includes the `GCDetails` for the most recent GC. This struct can be obtained via `getRTSStats()` (the old `getGCStats()` has been removed, and `getGCStatsEnabled()` has been renamed to `getRTSStatsEnabled()`) Improvements: * The per-GC stats and cumulative stats are now cleanly separated. * Inside the RTS we have a top-level `RTSStats` struct to keep all our stats in, previously this was just a collection of strangely-named variables. This struct is mostly just copied in `getRTSStats()`, so the implementation of that function is a lot shorter. * Types are more consistent. We use a uint64_t byte count for all memory values, and Time for all time values. * Names are more consistent. We use a suffix `_bytes` for all byte counts and `_ns` for all time values. * We now collect information about the amount of memory in large objects and compact objects in `GCDetails`. (the latter was the reason I started doing this patch but it seems to have ballooned a bit!) * I fixed a bug in the calculation of the elapsed MUT time, and added an ASSERT to stop the calculations going wrong in the future. For now I kept the Haskell API in `GHC.Stats` the same, by impedence-matching with the new API. We could either break that API and make it match the C API more closely, or we could add a new API and deprecate the old one. Opinions welcome. This stuff is very easy to get wrong, and it's hard to test. Reviews welcome! Test Plan: manual testing validate Reviewers: bgamari, niteria, austin, ezyang, hvr, erikd, rwbarton, Phyx Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2756
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