X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FThreads.c;h=0dee734baa0edfc15903a437c5e191c266c33067;hb=fff1f6194c3c39de53cd645bda9865fb131b1c68;hp=7344134a7d5a0d54e6a1d6bc60aa66c7c8277842;hpb=83d563cb9ede0ba792836e529b1e2929db926355;p=ghc-hetmet.git

diff --git a/rts/Threads.c b/rts/Threads.c
index 7344134..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;
 }
 
 /* ----------------------------------------------------------------------------