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Bug 88085

Summary:	top reports 0% iowait even when disk heavily used
Product:	[Retired] Red Hat Linux	Reporter:	Michael Young <m.a.young>
Component:	procps	Assignee:	Alexander Larsson <alexl>
Status:	CLOSED DEFERRED	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	9	CC:	anielsen, riel, wtogami
Target Milestone:	---
Target Release:	---
Hardware:	i386
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2003-08-05 09:13:22 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Michael Young 2003-04-05 12:02:37 UTC

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20030225

Description of problem:
The iowait field in top seems to be stuck at 0.0% even when the machine is under
heavy hard disk load. It looks like what should be reported as iowait is instead
included in the idle figure.

Comment 1 Alexander Larsson 2003-04-07 10:11:44 UTC

Looking at the code it seems top reads the iowait data from the fifth numeric
filed in the /proc/stat cpu line.

However, that field doesn't seem to exist. What's up with this?

Comment 2 Alexander Larsson 2003-04-07 10:15:50 UTC

Ah, this is apparently a 2.5.x kernel extension....

Comment 3 Rik van Riel 2003-07-14 12:45:48 UTC

indeed, iowait statistics is something in the 2.5 kernel (and RHEL)

it is not present in the standard 2.4 kernel

Comment 4 Alexander Larsson 2003-08-05 09:13:22 UTC

So, this will be fixed when we move to 2.6.

Comment 5 Michael Young 2003-08-05 10:03:57 UTC

Yes, indeed it does work if you boot with arjan's test 2.6 kernels.