Bug 88085 - top reports 0% iowait even when disk heavily used
Summary: top reports 0% iowait even when disk heavily used
Keywords:
Status: CLOSED DEFERRED
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: procps
Version: 9
Hardware: i386
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Alexander Larsson
QA Contact: Brian Brock
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2003-04-05 12:02 UTC by Michael Young
Modified: 2007-04-18 16:52 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2003-08-05 09:13:22 UTC
Embargoed:

Attachments (Terms of Use)

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.
Note You need to log in before you can comment on or make changes to this bug.