IO statistics - Revision history

Finist at 10:52, 12 May 2017

2017-05-12T10:52:21Z

2017-05-12T10:32:31Z

2015-08-31T23:16:01Z

‎See also: fix link

2015-08-07T09:24:07Z

Wrong "waiting" calculation

2015-07-08T19:45:53Z

‎See also: fix a link

2015-07-08T19:45:34Z

‎See also: added I/O limits

2013-06-25T23:38:20Z

formatting

2013-06-25T23:37:22Z

‎Format: reword

2013-06-25T23:35:58Z

‎Format: add unused fields, flush and fuse

2013-06-25T23:23:46Z

link to IO acct

← Older revision		Revision as of 10:52, 12 May 2017
Line 46:		Line 46:

	Example of parsing code: parse_proc_iostat() function in [https://src.openvz.org/projects/OVZ/repos/vzstat/browse/src/vzstat.c vzstat.c]		Example of parsing code: parse_proc_iostat() function in [https://src.openvz.org/projects/OVZ/repos/vzstat/browse/src/vzstat.c vzstat.c]
		+
		+	=== I/O schedulers ===
		+	Check available/active I/O schedulers for block device "sda":
		+	# cat /sys/block/sda/queue/scheduler
		+	noop deadline [cfq]
		+
		+	* for "cfq" I/O scheduler: a separate block device line is added in iostat proc file
		+	# cat /proc/bc/100/iostat
		+	flush 100 . 0 0 0 0 0 7389 1893968 0 0
		+	fuse 100 . 0 0 0 0 0 0 0 0 0
		+	sda 100 . 0 0 0 9000 1843380 245216 55845488 245028 188
		+
		+	* for "deadline" I/O scheduler: no additional per-device line is added, iops counters for such devices are added to "flush" line counters (iops limit works)
		+
		+	* for "noop" I/O scheduler: iops are not counted (iops limit does not work)
		+
		+	* for devices with no I/O scheduler (like logical devices, ceph rbd devices, etc): iops are not counted (iops limit does not work)
		+	# cat /sys/block/dm-0/queue/scheduler
		+	none
		+
		+	# cat /sys/block/rbd0/queue/scheduler
		+	none

	=== Queues ===		=== Queues ===

← Older revision		Revision as of 10:32, 12 May 2017
Line 44:		Line 44:

	Separate stats exist for fuse and flush, that only report requests and sectors stats (others are always 0).		Separate stats exist for fuse and flush, that only report requests and sectors stats (others are always 0).
		+
		+	Example of parsing code: parse_proc_iostat() function in [https://src.openvz.org/projects/OVZ/repos/vzstat/browse/src/vzstat.c vzstat.c]

	=== Queues ===		=== Queues ===

@@ Line 88: / Line 88: @@
 * [[IO accounting]]
 * [[I/O priorities]]
-* [[I/O_limits]]
+* [[I/O limits]]

@@ Line 62: / Line 62: @@
   active  = sum(b.used_time - a.used_time) * 100 / interval;
-  waiting = sum(b.wait_time - b.wait_time) * 100 / interval;
+  waiting = sum(b.wait_time - a.wait_time) * 100 / interval;
   idle    = 100 - (active + waiting);

@@ Line 87: / Line 87: @@
 == See also ==
 * [[IO accounting]]
-* [[I/O priorities for containers]]
+* [[I/O priorities]]
 * [[I/O_limits]]

← Older revision		Revision as of 19:45, 8 July 2015
Line 88:		Line 88:
	* [[IO accounting]]		* [[IO accounting]]
	* [[I/O priorities for containers]]		* [[I/O priorities for containers]]
		+	* [[I/O_limits]]

@@ Line 3: / Line 3: @@
 == Kernel interface  ==
-The stats in question are reported via the proc files. Currently it is available in kernels starting from 028stab069.1.
+The stats are reported via the proc files. Currently it is available in kernels starting from 028stab069.1.
 === Files ===
-* /proc/bc/$id/iostat
+* <code>/proc/bc/$id/iostat</code>
 : statistics for beancounter $id
-* /proc/bc/iostat
+* <code>/proc/bc/iostat</code>
 : statistics for all beancounters

@@ Line 43: / Line 43: @@
 New columns might be added at the end of row in future.
-Separate stats exist for fuse and flush, with the only numeric fields shown are 9 and 10, others are set to 0.
+Separate stats exist for fuse and flush, that only report requests and sectors stats (others are always 0).
 === Queues ===

@@ Line 20: / Line 20: @@
 ! N	!! name	!! type	!! description
 |-
-| 1	|| disk	|| string	|| Disk device name, e.g. sda or hda
+| 1	|| disk	|| string	|| Disk device name, e.g. sda or hda, or a special queue (like fuse or flush)
 |-
 | 2	|| ub id || integer	|| Beancounter id
 |-
-| 3	|| state || char	|| currently unused
+| 3	|| state || char	|| currently unused (always '.')
 |-
 | 4	|| busy queues	|| integer	|| The number of queues with requests (see below)
 |-
-| 5	|| on dispatch	|| integer	|| The number of requests dispatched to a hardware
+| 5	|| on dispatch	|| integer	|| currently unused (always '0')
 |-
-| 6	|| activations count	|| integer	|| The number of switches to active state
+| 6	|| activations count	|| integer	|| currently unused (always '0')
 |-
 | 7	|| wait time	 || integer	 || Total time in waiting state in milliseconds
@@ Line 41: / Line 41: @@
 |}
-New columns might be added at the end of row in future!
+New columns might be added at the end of row in future.
 === Queues ===

@@ Line 1: / Line 1: @@
-This page describes the IO statistics that is collected at the IO-scheduler level. It describes the information about the container's real work with disks.
+This page describes the IO statistics that is collected at the IO-scheduler level. It describes the information about the container's real work with disks. This is different from what shown by [[IO accounting]].
 == Kernel interface  ==
@@ Line 82: / Line 82: @@
 denotes the average request size for a beancounter to a particular disk.