Messages in this thread | | | Subject | PROBLEM: Heavy iowait on 2.6 kernels | From | Guy Van Sanden <> | Date | Fri, 11 Jun 2004 10:35:05 +0200 |
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I recently discovered why my new Gentoo server slows to a crawl on a intermediate load on the 2.6 kernel series. The reason seems to be an unusual amount of iowait. I can reproduce this on two systems, one with a KT400 and and one with Sis735 chipset.
iostat -c 1 (or vmstat) while running something like bonnie produces iowaits of 99%. Any 2.6 kernel responds the same (regardless of the patchset), even vanilla. (2.6.5-mm, 2.6.6-mm, 2.6.6-vanilla and 2.6.5-gentoo-r1). Any 2.4-series kernel is fine.
This is a sample iostat output -- avg-cpu: %user %nice %sys %iowait %idle 26.73 0.00 10.89 62.38 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.00 0.00 13.00 87.00 0.00 avg-cpu: %user %nice %sys %iowait %idle 1.01 0.00 16.16 82.83 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.00 0.00 11.88 88.12 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.00 0.00 1.01 98.99 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.99 0.00 2.97 96.04 0.00 -- -- ______________________________________________________________________
Guy Van Sanden http://unixmafia.port5.com
Registered Linux user #249404 - September 1997 ______________________________________________________________________
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