| Does 2.6.18 support/account io wait cpu time [message #13136] |
Mon, 21 May 2007 12:01  |
rickb
Messages: 368
Registered: October 2006
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Senior Member |
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Hello. I have been upgrading my nodes from openvz 2.6.9 to 2.6.18. One of the major indicators of a nodes workload to me is the % of time spent in iowait over various time periods. I immediately noticed that 2.6.18 reported no iowait which I assumed was due to better fs caching, prioritization, per ve io fairness, etc. But, now I think that iowait is included in idle time. After running processes which undoubtedly introduce iowait (raid recovery, mkfs, bonnie++, etc) to a system, none is accounted.
Am I missing something, is this a bug?
sar, dstat, vmstat, etc all report 0% iowait (but I think theres some there!)
12:00:01 AM CPU %user %nice %system %iowait %idle
12:10:01 AM all 0.33 0.00 0.48 0.00 99.19
12:20:01 AM all 0.27 0.00 0.37 0.00 99.36
12:30:01 AM all 0.22 0.00 0.33 0.00 99.45
12:40:01 AM all 1.55 0.01 0.73 0.00 97.71
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I can approve that in current 2.6.18 OVZ kernel iowait statistic is broken, so I filled the bug report: 
