diff -r 3f46ab998f18 -r fa02c2ef7a70 hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Tue Nov 10 11:32:48 2009 -0800
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Fri Nov 13 11:55:26 2009 -0800
@@ -1516,8 +1516,31 @@
       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
     update_recent_gc_times(end_time_sec, elapsed_ms);
     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
-    // using 1.01 to account for floating point inaccuracies
-    assert(recent_avg_pause_time_ratio() < 1.01, "All GC?");
+    if (recent_avg_pause_time_ratio() < 0.0 ||
+        (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
+#ifndef PRODUCT
+      // Dump info to allow post-facto debugging
+      gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
+      gclog_or_tty->print_cr("-------------------------------------------");
+      gclog_or_tty->print_cr("Recent GC Times (ms):");
+      _recent_gc_times_ms->dump();
+      gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
+      _recent_prev_end_times_for_all_gcs_sec->dump();
+      gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
+                             _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
+      // TEMPORARY: In debug mode, terminate the JVM, so nightly testing explicitly
+      // flags the sighting by failing the test.
+      assert(false, "Debugging data for CR 6898948 has been dumped above");
+#else  // PRODUCT
+      // Clip ratio between 0.0 and 1.0
+      if (_recent_avg_pause_time_ratio < 0.0) {
+        _recent_avg_pause_time_ratio = 0.0;
+      } else {
+        assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
+        _recent_avg_pause_time_ratio = 1.0;
+      }
+#endif  // PRODUCT
+    }
   }
 
   if (G1PolicyVerbose > 1) {