diff --git a/tools/perf/Documentation/perf-list.txt b/tools/perf/Documentation/perf-list.txt
index 138fb6e..18ed1b0 100644
--- a/tools/perf/Documentation/perf-list.txt
+++ b/tools/perf/Documentation/perf-list.txt
@@ -199,6 +199,18 @@
 
   perf stat -C 0 -e 'hv_gpci/dtbp_ptitc,phys_processor_idx=0x2/' ...
 
+EVENT QUALIFIERS:
+
+It is also possible to add extra qualifiers to an event:
+
+percore:
+
+Sums up the event counts for all hardware threads in a core, e.g.:
+
+
+  perf stat -e cpu/event=0,umask=0x3,percore=1/
+
+
 EVENT GROUPS
 ------------