Does 2.6.18 support/account io wait cpu time
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
Re: Does 2.6.18 support/account io wait cpu time
Kir, dev, Vasily- can you give me your thoughts on this? Do you know if the 2.6.18 kernel records cpu accoutning differently and I need to update vmstat? This is rather important to me, because now I feel like I do not know how much cpu idle time there really is (as it could all be iowait). Thanks! Rick
Hello Rick, Sorry, I've somehow missed your message! I can approve that in current 2.6.18 OVZ kernel iowait statistic is broken, so I filled the bug report: http://bugzilla.openvz.org/show_bug.cgi?id=588 Thank you for the report, Vasily