X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FThreads.c;h=0dee734baa0edfc15903a437c5e191c266c33067;hb=fff1f6194c3c39de53cd645bda9865fb131b1c68;hp=6635ed51e550f174f1342d73cf8bb305906b44d3;hpb=fd316eba4747cf8bb9381e06c7afc3c024e1e5c1;p=ghc-hetmet.git

diff --git a/rts/Threads.c b/rts/Threads.c
index 6635ed5..0dee734 100644
--- a/rts/Threads.c
+++ b/rts/Threads.c
@@ -284,6 +284,19 @@ unblock:
     // we'll block again.
     tso->why_blocked = NotBlocked;
     appendToRunQueue(cap,tso);
+
+    // We used to set the context switch flag here, which would
+    // trigger a context switch a short time in the future (at the end
+    // of the current nursery block).  The idea is that we have just
+    // woken up a thread, so we may need to load-balance and migrate
+    // threads to other CPUs.  On the other hand, setting the context
+    // switch flag here unfairly penalises the current thread by
+    // yielding its time slice too early.
+    //
+    // The synthetic benchmark nofib/smp/chan can be used to show the
+    // difference quite clearly.
+
+    // cap->context_switch = 1;
 }
 
 /* ----------------------------------------------------------------------------
@@ -492,8 +505,8 @@ printThreadBlockage(StgTSO *tso)
   case BlockedOnCCall:
     debugBelch("is blocked on an external call");
     break;
-  case BlockedOnCCall_NoUnblockExc:
-    debugBelch("is blocked on an external call (exceptions were already blocked)");
+  case BlockedOnCCall_Interruptible:
+    debugBelch("is blocked on an external call (but may be interrupted)");
     break;
   case BlockedOnSTM:
     debugBelch("is blocked on an STM operation");