Description of problem: Related to Bugzilla Bug 145950 â high loads / high iowait / up 100% cpu time for kscand on oracle box: We have 4 Oracle RAC cluster nodes running RHEL3 Update 6 x86, each having 8GB RAM and SGA is currently set to 1.7GB. The problem we are having is that we get periodic CPU spikes every 5 minutes where the kscand process take up to 100% of the CPU usage and the load shoots up to a value between 50 - 90. We are currently running Kernel 2.4.21-37.ELsmp which according to advisory RHSA-2005-663 addresses the problem we are having by supporting: - support for new "oom-kill" and "kscand_work_percent" sysctls We would like to know exactly how best to set the tunable "/proc/sys/vm/kscand_work_percent" to solve/alleviate the problem we presently have. We are running Oracle without hugepages. Currently it is set to the default setting: 100. Please provide recommendations for this value and instructions for how to set it. Also please indicate if there is anything new/other than the above that can be done to address this problem. Version-Release number of selected component (if applicable): 2.4.21-37.ELsmp How reproducible: It's ongoing. Any recommendation for how to possibly reproduce/further debug the problem? Steps to Reproduce: When the servers were idle we did not notice this problem. However when me moved the servers into production and started getting load, the problem became apparanet right away.
Please set /proc/sys/vm/kscand_work_percent to 100 and leave the oom-kill tunable with the default value. Please let me know if this solves your problem. Thanks, Larry Woodman
This bug is filed against RHEL 3, which is in maintenance phase. During the maintenance phase, only security errata and select mission critical bug fixes will be released for enterprise products. Since this bug does not meet that criteria, it is now being closed. For more information of the RHEL errata support policy, please visit: http://www.redhat.com/security/updates/errata/ If you feel this bug is indeed mission critical, please contact your support representative. You may be asked to provide detailed information on how this bug is affecting you.