diff --git a/doc/source/zuul.rst b/doc/source/zuul.rst
index 6e9fb05..8a6120d 100644
--- a/doc/source/zuul.rst
+++ b/doc/source/zuul.rst
@@ -1050,9 +1050,11 @@
   ./tools/zuul-changes.py --review-host=review.openstack.org \
       http://zuul.openstack.org/ check 'recheck no bug'
 
-If you send a SIGUSR2 to the zuul-server process, Zuul will dump a stack
-trace for each running thread into its debug log. This is useful for
-tracking down deadlock or otherwise slow threads.
+If you send a SIGUSR2 to the zuul-server process, or the forked process
+that runs the Gearman daemon, Zuul will dump a stack trace for each
+running thread into its debug log. It is written under the log bucket
+``zuul.stack_dump``.  This is useful for tracking down deadlock or
+otherwise slow threads.
 
 When `yappi <https://code.google.com/p/yappi/>`_ (Yet Another Python
 Profiler) is available, additional functions' and threads' stats are