block: add documentation for inflight

Complements v2.6.32 commit a9327ca ("Seperate read and write statistics of in_flight requests") and commit 316d315 ("block: Seperate read and write statistics of in_flight requests v2"). Signed-off-by: Steffen Maier <[email protected]> Reviewed-by: Jens Axboe <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
fracktal · Oct 19, 2021 · 7b5f801 · 7b5f801
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commit 7b5f801
Showing 1 changed file with 16 additions and 0 deletions.
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
@@ -28,6 +28,22 @@ Description:
 		For more details refer Documentation/admin-guide/iostats.rst
 
 
+What:		/sys/block/<disk>/inflight
+Date:		October 2009
+Contact:	Jens Axboe <[email protected]>, Nikanth Karthikesan <[email protected]>
+Description:
+		Reports the number of I/O requests currently in progress
+		(pending / in flight) in a device driver. This can be less
+		than the number of requests queued in the block device queue.
+		The report contains 2 fields: one for read requests
+		and one for write requests.
+		The value type is unsigned int.
+		Cf. Documentation/block/stat.rst which contains a single value for
+		requests in flight.
+		This is related to nr_requests in Documentation/block/queue-sysfs.rst
+		and for SCSI device also its queue_depth.
+
+
 What:		/sys/block/<disk>/diskseq
 Date:		February 2021
 Contact:	Matteo Croce <[email protected]>