Re: unusually high load averages

On Fri, 30 Jan 2004, John Baldwin wrote:

> On Friday 30 January 2004 12:03 pm, Bruce Evans wrote:
> > High load average despite only idle processes running:
> > This seems to be scheduler-independent.  Running top to watch the load
> > average raises the load average by about 0.1.  I think the problem is
> > that loadav() is now a kthread that restarted by a timeout, so it now
> > sees a herd of other processes that are restarted by the same timeout.
> > Previously it was run as a timeout and other threads were put on the
> > run queue by a timeout; the ordering of the timeouts was hopefully
> > random so that loadav() saw the correct number of processes restarted
> > by timeouts, on average.  Now loadav() sees all lower priority processes
> > that are restarted by the same timeout (since they are all restarted but
> > loadav() runs first).
>
> If loadav is truly unimportant, we could give it a fairly low priority so
> other processes ran first.

Then it would be strongly biased in the opposite direction.

I just remembered that its table of exponentionals became slightly wrong
when jitter was added to its timeout.  The error increases with the amount
of jitter and the jitter could reach many seconds if it were a low priority
process.

Bruce