Make clearNursery free

Summary:
clearNursery resets all the bd->free pointers of nursery blocks to
make the blocks empty.  In profiles we've seen clearNursery taking
significant amounts of time particularly with large -N and -A values.

This patch moves the work of clearNursery to the point at which we
actually need the new block, thereby introducing an invariant that
blocks to the right of the CurrentNursery pointer still need their
bd->free pointer reset.  This should make things faster overall,
because we don't need to clear blocks that we don't use.

Test Plan: validate

Reviewers: AndreasVoellmy, ezyang, austin

Subscribers: thomie, carter, ezyang, simonmar

Differential Revision: https://phabricator.haskell.org/D318

1 files changed, 1 insertions, 20 deletions

diff --git a/rts/Stats.c b/rts/Stats.c
index ed345c2894..d5efaa2330 100644
--- a/rts/Stats.c
+++ b/rts/Stats.c
@@ -291,27 +291,8 @@ stat_startGC (Capability *cap, gc_thread *gct)
     {
         gct->gc_start_faults = getPageFaults();
     }
-}
-
-/* -----------------------------------------------------------------------------
- * Calculate the total allocated memory since the start of the
- * program.  Also emits events reporting the per-cap allocation
- * totals.
- * -------------------------------------------------------------------------- */
-
-static StgWord
-calcTotalAllocated(void)
-{
-    W_ tot_alloc = 0;
-    W_ n;
-    for (n = 0; n < n_capabilities; n++) {
-        tot_alloc += capabilities[n]->total_allocated;
-        traceEventHeapAllocated(capabilities[n],
-                                CAPSET_HEAP_DEFAULT,
-                                capabilities[n]->total_allocated * sizeof(W_));
-    }
 
-    return tot_alloc;
+    updateNurseriesStats();
 }
 
 /* -----------------------------------------------------------------------------