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-rw-r--r--Documentation/accounting/psi.rst3
1 files changed, 2 insertions, 1 deletions
diff --git a/Documentation/accounting/psi.rst b/Documentation/accounting/psi.rst
index f2b3439edcc2..860fe651d645 100644
--- a/Documentation/accounting/psi.rst
+++ b/Documentation/accounting/psi.rst
@@ -92,7 +92,8 @@ Triggers can be set on more than one psi metric and more than one trigger
for the same psi metric can be specified. However for each trigger a separate
file descriptor is required to be able to poll it separately from others,
therefore for each trigger a separate open() syscall should be made even
-when opening the same psi interface file.
+when opening the same psi interface file. Write operations to a file descriptor
+with an already existing psi trigger will fail with EBUSY.
Monitors activate only when system enters stall state for the monitored
psi metric and deactivates upon exit from the stall state. While system is