Linux: High Idle Load Average

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When a Linux user reported a repeatedly high load average on an idle server, tracking the problem to a specific patch labeled, "user of the jiffies rounding code", Andrew Morton replied, "this is unexpected. High load average is due to either a task chewing a lot of CPU time or a task stuck in uninterruptible sleep."

Linus Torvalds disagreed, explaining, "We saw high loadaverages with the timer bogosity with 'gettimeofday()' and 'select()' not agreeing, so they would do things like 'date = time(..); select(.. , timeout = );' and when 'date' wasn't taking the jiffies offset into account, and thus mixing these kinds of different time sources, the select ended up returning immediately because they effectively used different clocks, and suddenly we had some applications chewing up 30% CPU time, because they were in a loop that *tried* to sleep."

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