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, 7 insertions, 1 deletions

diff --git a/rts/sm/Storage.c b/rts/sm/Storage.c
index 86bd1c2bb3..865a890fcc 100644
--- a/rts/sm/Storage.c
+++ b/rts/sm/Storage.c
@@ -684,7 +684,10 @@ StgPtr allocate (Capability *cap, W_ n)
 
     TICK_ALLOC_HEAP_NOCTR(WDS(n));
     CCS_ALLOC(cap->r.rCCCS,n);
-    
+    if (cap->r.rCurrentTSO != NULL) {
+        cap->r.rCurrentTSO->alloc_limit -= n*sizeof(W_);
+    }
+
     if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
         W_ req_blocks =  (W_)BLOCK_ROUND_UP(n*sizeof(W_)) / BLOCK_SIZE;
 
@@ -821,6 +824,9 @@ allocatePinned (Capability *cap, W_ n)
 
     TICK_ALLOC_HEAP_NOCTR(WDS(n));
     CCS_ALLOC(cap->r.rCCCS,n);
+    if (cap->r.rCurrentTSO != NULL) {
+        cap->r.rCurrentTSO->alloc_limit -= n*sizeof(W_);
+    }
 
     bd = cap->pinned_object_block;