zpool-events.8: document zio_type and zio_priority

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Signed-off-by: Rob Norris <[email protected]>

Author: robn

man/man8/zpool-events.8

@@ -26,9 +26,9 @@
 .\" Copyright (c) 2018 George Melikov. All Rights Reserved.
 .\" Copyright 2017 Nexenta Systems, Inc.
 .\" Copyright (c) 2017 Open-E, Inc. All Rights Reserved.
-.\" Copyright (c) 2024, Klara Inc.
+.\" Copyright (c) 2024, 2025, Klara, Inc.
 .\"
-.Dd February 28, 2024
+.Dd May 27, 2025
 .Dt ZPOOL-EVENTS 8
 .Os
 .
@@ -308,6 +308,16 @@ The valid pipeline stages for the I/O.
 See the
 .Sy I/O STAGES
 section for a full list of all the I/O stages.
+.It Sy zio_priority
+The queue priority of the I/O request.
+See the
+.Sy I/O PRIORITIES
+section for a full list of all the I/O priorities.
+.It Sy zio_tyoe
+The type of the I/O request.
+See the
+.Sy I/O TYPES
+section for a full list of all the I/O types.
 .It Sy zio_delay
 The time elapsed (in nanoseconds) waiting for the block layer to complete the
 I/O request.
@@ -477,6 +487,51 @@ ZIO_FLAG_DELEGATED:0x40000000
 ZIO_FLAG_FASTWRITE:0x80000000
 .TE
 .
+.Sh I/O TYPES
+Every I/O request in the pipeline has a single type value.
+This value describes the kind of low-level work the I/O represents.
+This value will be set in an event as a
+.Sy zio_type
+payload entry.
+.Pp
+.TS
+tab(:);
+l l l .
+Type:Value:Description
+_:_:_
+ZIO_TYPE_NULL:0x0:internal I/O sync point
+ZIO_TYPE_READ:0x1:data read
+ZIO_TYPE_WRITE:0x2:data write
+ZIO_TYPE_FREE:0x3:block free
+ZIO_TYPE_CLAIM:0x4:block claim (ZIL replay)
+ZIO_TYPE_FLUSH:0x5:disk cache flush request
+ZIO_TYPE_TRIM:0x6:trim (discard)
+.TE
+.
+.Sh I/O PRIORITIES
+Every I/O request in the pipeline has a single priority value.
+This value is used by the queuing code to decide which I/O to issue next.
+This value will be set in an event as a
+.Sy zio_priority
+payload entry.
+.Pp
+.TS
+tab(:);
+l l l .
+Type:Value:Description
+_:_:_
+ZIO_PRIORITY_SYNC_READ:0x0:
+ZIO_PRIORITY_SYNC_WRITE:0x1:ZIL
+ZIO_PRIORITY_ASYNC_READ:0x2:prefetch
+ZIO_PRIORITY_ASYNC_WRITE:0x3:spa_sync()
+ZIO_PRIORITY_SCRUB:0x4:asynchronous scrub/resilver reads
+ZIO_PRIORITY_REMOVAL:0x5:reads/writes for vdev removal
+ZIO_PRIORITY_INITIALIZING:0x6:initializing I/O
+ZIO_PRIORITY_TRIM:0x7:trim I/O (discard)
+ZIO_PRIORITY_REBUILD:0x8:reads/writes for vdev rebuild
+ZIO_PRIORITY_NOW:0xa:non-queued i/os (e.g. free)
+.TE
+.
 .Sh SEE ALSO
 .Xr zfs 4 ,
 .Xr zed 8 ,