[commit: ghc] master: Call busy_wait_nop() in the spin-wait loop in shutdown_gc_threads() (9c3c152)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/9c3c1527860cda84b1395f6936937cd094fb7744/ghc

>---------------------------------------------------------------

commit 9c3c1527860cda84b1395f6936937cd094fb7744
Author: Patrick Palka <patrick at parcs.ath.cx>
Date:   Fri Nov 29 20:01:27 2013 -0500

    Call busy_wait_nop() in the spin-wait loop in shutdown_gc_threads()


>---------------------------------------------------------------

9c3c1527860cda84b1395f6936937cd094fb7744
 rts/sm/GC.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/rts/sm/GC.c b/rts/sm/GC.c
index 58698e9..8cae2c9 100644
--- a/rts/sm/GC.c
+++ b/rts/sm/GC.c
@@ -1182,7 +1182,10 @@ shutdown_gc_threads (nat me USED_IF_THREADS)
 
     for (i=0; i < n_gc_threads; i++) {
         if (i == me || gc_threads[i]->idle) continue;
-        while (gc_threads[i]->wakeup != GC_THREAD_WAITING_TO_CONTINUE) { write_barrier(); }
+        while (gc_threads[i]->wakeup != GC_THREAD_WAITING_TO_CONTINUE) {
+            busy_wait_nop();
+            write_barrier();
+        }
     }
 #endif
 }