Overhaul GC stats

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

1 files changed, 1 insertions, 32 deletions

diff --git a/includes/Rts.h b/includes/Rts.h
index be81b0d9c7..0599df655c 100644
--- a/includes/Rts.h
+++ b/includes/Rts.h
@@ -39,6 +39,7 @@ extern "C" {
 #endif
 
 #include "rts/Types.h"
+#include "rts/Time.h"
 
 #if __GNUC__ >= 3
 #define ATTRIBUTE_ALIGNED(n) __attribute__((aligned(n)))
@@ -145,38 +146,6 @@ void _assertFail(const char *filename, unsigned int linenum)
 #define FMT_HexSizeT "zx"
 
 /* -----------------------------------------------------------------------------
-   Time values in the RTS
-   -------------------------------------------------------------------------- */
-
-// For most time values in the RTS we use a fixed resolution of nanoseconds,
-// normalising the time we get from platform-dependent APIs to this
-// resolution.
-#define TIME_RESOLUTION 1000000000
-typedef StgInt64 Time;
-
-#define TIME_MAX HS_INT64_MAX
-
-#if TIME_RESOLUTION == 1000000000
-// I'm being lazy, but it's awkward to define fully general versions of these
-#define TimeToUS(t)      ((t) / 1000)
-#define TimeToNS(t)      (t)
-#define USToTime(t)      ((Time)(t) * 1000)
-#define NSToTime(t)      ((Time)(t))
-#else
-#error Fix TimeToNS(), TimeToUS() etc.
-#endif
-
-#define SecondsToTime(t) ((Time)(t) * TIME_RESOLUTION)
-#define TimeToSeconds(t) ((t) / TIME_RESOLUTION)
-
-// Use instead of SecondsToTime() when we have a floating-point
-// seconds value, to avoid truncating it.
-INLINE_HEADER Time fsecondsToTime (double t)
-{
-    return (Time)(t * TIME_RESOLUTION);
-}
-
-/* -----------------------------------------------------------------------------
    Include everything STG-ish
    -------------------------------------------------------------------------- */