Per-thread allocation counters and limits

This tracks the amount of memory allocation by each thread in a
counter stored in the TSO.  Optionally, when the counter drops below
zero (it counts down), the thread can be sent an asynchronous
exception: AllocationLimitExceeded.  When this happens, given a small
additional limit so that it can handle the exception.  See
documentation in GHC.Conc for more details.

Allocation limits are similar to timeouts, but

  - timeouts use real time, not CPU time.  Allocation limits do not
    count anything while the thread is blocked or in foreign code.

  - timeouts don't re-trigger if the thread catches the exception,
    allocation limits do.

  - timeouts can catch non-allocating loops, if you use
    -fno-omit-yields.  This doesn't work for allocation limits.

I couldn't measure any impact on benchmarks with these changes, even
for nofib/smp.

1 files changed, 5 insertions, 1 deletions

diff --git a/rts/RaiseAsync.h b/rts/RaiseAsync.h
index 1f61b8c72d..65ca4f5103 100644
--- a/rts/RaiseAsync.h
+++ b/rts/RaiseAsync.h
@@ -28,7 +28,11 @@ void throwToSingleThreaded_ (Capability *cap,
 			     StgClosure *exception, 
 			     rtsBool stop_at_atomically);
 
-void suspendComputation (Capability *cap, 
+void throwToSelf (Capability *cap,
+                  StgTSO *tso,
+                  StgClosure *exception);
+
+void suspendComputation (Capability *cap,
 			 StgTSO *tso, 
 			 StgUpdateFrame *stop_here);