> Load is a very... debatable... metric. > http://www.teamquest.com/resources/gunther/display/5/index.htm
Great article, thanks! Unfortunately, it falls far short of addressing the current question. The article is all about what the words "load" and "average" mean in unix tools that show a "load average" metric. It clarifies two key points: 1. "load" refers to the CPU run queue length and is indirectly related to CPU utilization but not the same thing. It is basically the number of running processes over time.; 2. "average" means a damped, time-dependent average, not a simple numeric average. The article shows how often the kernel calculates the numbers and what calculation it performs. These facts are not so much debatable as just misunderstood. Unfortunately, it does not even begin to explain how the kernel could *incorrectly* report system load, causing sar and top to give grossly misleading output, and it does not address the critical "iowait" metric, which is what I mainly watch because it indicates situations when performance is disk bound. In my situation, heartbeat is having trouble sending local status updates, and it happens when the system *appears* to show high idle and low iowait metrics. Off to the kernel list... -- Eric Robinson Disclaimer - October 16, 2009 This email and any files transmitted with it are confidential and intended solely for General Linux-HA mailing list. If you are not the named addressee you should not disseminate, distribute, copy or alter this email. Any views or opinions presented in this email are solely those of the author and might not represent those of Physician Select Management and Physician's Managed Care. Warning: Although Physician Select Management and Physician's Managed Care have taken reasonable precautions to ensure no viruses are present in this email, the companies cannot accept responsibility for any loss or damage arising from the use of this email or attachments. This disclaimer was added by Policy Patrol: http://www.policypatrol.com/ _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
