run-queue length question

[Konstantin Belousov]

On Sun, Jul 06, 2014 at 02:32:12PM +0300, Stefan Parvu wrote:
> Hi,
> 
> Im trying to understand what FreeBSD kernel counts for run-queue length. 
> 
> Traditional we count as queue length: number of processes which are running plus 
> the number that are runnable (waiting to execute) - we *dont* count processes waiting 
> for storage, network etc. 
> 
> Linux kernel has added into run-queue length the iowait processes which makes
> load average values big and disproportionate to the reality for example during 
> disk io tests.
> 
> How does FreeBSD handle this part ? Is the queue length simple the number of 
> running processes + waiting to run or not as we used to have in UNIX world ?

It is the Linux which follows the traditional definition of the load,
by counting running, ready to run and 'blocked on the fast i/o' processes
as adding to the load average.  Also, I remember that FreeBSD up to 4.x
followed this definition.

Sometime during the 5.x rewrites the load was redefined to only count
running + ready to run threads, which is the current definition, used by LA.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-hackers/attachments/20140706/4f46c2d0/attachment.sig>