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-rw-r--r--Documentation/block/stat.rst14
1 files changed, 12 insertions, 2 deletions
diff --git a/Documentation/block/stat.rst b/Documentation/block/stat.rst
index 9c07bc22b0bc..77311335c08b 100644
--- a/Documentation/block/stat.rst
+++ b/Documentation/block/stat.rst
@@ -41,6 +41,8 @@ discard I/Os requests number of discard I/Os processed
discard merges requests number of discard I/Os merged with in-queue I/O
discard sectors sectors number of sectors discarded
discard ticks milliseconds total wait time for discard requests
+flush I/Os requests number of flush I/Os processed
+flush ticks milliseconds total wait time for flush requests
=============== ============= =================================================
read I/Os, write I/Os, discard I/0s
@@ -48,6 +50,14 @@ read I/Os, write I/Os, discard I/0s
These values increment when an I/O request completes.
+flush I/Os
+==========
+
+These values increment when an flush I/O request completes.
+
+Block layer combines flush requests and executes at most one at a time.
+This counts flush requests executed by disk. Not tracked for partitions.
+
read merges, write merges, discard merges
=========================================
@@ -62,8 +72,8 @@ discarded from this block device. The "sectors" in question are the
standard UNIX 512-byte sectors, not any device- or filesystem-specific
block size. The counters are incremented when the I/O completes.
-read ticks, write ticks, discard ticks
-======================================
+read ticks, write ticks, discard ticks, flush ticks
+===================================================
These values count the number of milliseconds that I/O requests have
waited on this block device. If there are multiple I/O requests waiting,