Don't traverse the entire list of threads on every GC (phase 1)

Instead of keeping a single list of all threads, keep one per step
and only look at the threads belonging to steps that we are
collecting.

1 files changed, 3 insertions, 1 deletions

diff --git a/rts/sm/Compact.c b/rts/sm/Compact.c
index fa6efa9f4e..c5f0c37130 100644
--- a/rts/sm/Compact.c
+++ b/rts/sm/Compact.c
@@ -986,7 +986,9 @@ compact(StgClosure *static_objects)
     }
 
     // the global thread list
-    thread((void *)&all_threads);
+    for (s = 0; s < total_steps; s++) {
+        thread((void *)&all_steps[s].threads);
+    }
 
     // any threads resurrected during this GC
     thread((void *)&resurrected_threads);