On Wed, 2008-04-23 at 23:33 +1000, Sonia Hamilton wrote: > A question about uptime. My understanding of the load average figures is > that a figure less than 2.0 on a 2 CPU machine means the CPUs don't have > more work than they can keep up with (on average).
As an aside, It is interesting to note that "maxing out" (1.0 on one CPU, 2.0 on two, etc) the load average does not necessarily imply the best use of a machine. I know the gent who runs the image farm at Amazon. Unsurprisingly, Amazon's high level IT people wanted all the systems to be fully utilized - but the point of the image servers is *not* to be running without any CPU idling, but to be serving images with extremely low latency. So in this case, they needed a very beefy set of machines that were running at as close to idle as they could so that any new request coming in could be acted on immediately. He had such a bad time of trying to explain latency to senior IT that finally he gave up and hacked the kernel so that it reported artificially high load averages to trick out the external monitoring agents so the IT managers wouldn't feel that they could lump more services onto the box, thereby increasing their "utilization" at the cost of completely destroying responsiveness. AfC Sydney -- Andrew Frederick Cowie Operational Dynamics is an operations and engineering consultancy focusing on IT strategy, organizational architecture, systems review, and effective procedures for change management. We actively carry out research and development in these areas on behalf of our clients, and enable successful use of open source in their mission critical enterprises, worldwide. http://www.operationaldynamics.com/ Sydney New York Toronto London
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