Re: High load average on disk I/O on 2.6.17-rc3

On Mon, 2006-05-08 at 17:22 +0200, Erik Mouw wrote:
On Mon, May 08, 2006 at 04:55:48PM +0200, Arjan van de Ven wrote:
On Mon, 2006-05-08 at 07:24 -0700, Martin J. Bligh wrote:
It's pretty harmless though. The "load average" thing just means that the
extra pdflush threads are twiddling thumbs waiting on some disk I/O -
they'll later exit and clean themselves up. They won't be consuming
significant resources.

If they're waiting on disk I/O, they shouldn't be runnable, and thus
should not be counted as part of the load average, surely?

yes they are, since at least a decade. "load average" != "cpu
utilisation" by any means. It's "tasks waiting for a hardware resource
to become available". CPU is one such resource (runnable) but disk is
another. There are more ...

... except that any kernel < 2.6 didn't account tasks waiting for disk
IO.

they did. It was "D" state, which counted into load average.



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