load average with multi-core CPU's

Ivan Voras ivoras at freebsd.org
Mon Sep 26 15:14:07 UTC 2011


On 22/09/2011 22:59, Rodrigo Gonzalez wrote:

> It is the number of task waiting in queue to be run....but IO is
> important...if 2 processes are waiting for IO and it is completely
> saturated they will be kept in queue so load will get higher

No, this is how Linux does the calculation. For FreeBSD, if a process is
waiting or IO, it is sleeping and thus not runnable.

Linux has the "iowait" ("w") state in addition to usr/sys/idle states
and counts processes waiting for IO as runnable - which never made sense
to me as it is counting apples as oranges. (yes, IO saturation is
important for server status but it needs to be inspected separately -
the LA number is too coarse for this).


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