From: Simon Marlow <marlowsd@gmail.com>
Date: Thu, 23 Oct 2008 15:50:17 +0000 (+0000)
Subject: Fix a bug in the new scheduler
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=bd6fe3a37cefc235c5abf08557635031678d65e4

Fix a bug in the new scheduler
If the current thread blocks, we should yield the Capability
immediately, because the thread and hence possibly the current Task
are now owned by someone else.  This worked in the old scheduler, but
we moved where the yield happens in the new scheduler which broke it.
---

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 2e9d0dd..cc5cbb4 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -399,6 +399,7 @@ schedule (Capability *initialCapability, Task *task)
     //     ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);
     }
 
+  yield:
     scheduleYield(&cap,task);
     if (emptyRunQueue(cap)) continue; // look for work again
 #endif
@@ -565,7 +566,7 @@ run_thread:
 	debugTrace(DEBUG_sched,
 		   "--<< thread %lu (%s) stopped: blocked",
 		   (unsigned long)t->id, whatNext_strs[t->what_next]);
-	continue;
+        goto yield;
     }
 #endif