Re: [patch] sched-2.5.59-A2

Erich Focht
2003-01-17T15:21:10Z

On Friday 17 January 2003 16:11, Ingo Molnar wrote:
> On Fri, 17 Jan 2003, Erich Focht wrote:
> > I like the cleanup of the topology.h. Also the renaming to
> > prev_cpu_load. There was a mistake (I think) in the call to
> > load_balance() in the idle path, guess you wanted to have:
> > + load_balance(this_rq, 1, __node_to_cpu_mask(this_node));
> > instead of
> > + load_balance(this_rq, 1, this_cpumask);
> > otherwise you won't load balance at all for idle cpus.
>
> indeed - there was another bug as well, the 'idle' parameter to
> load_balance() was 1 even in the busy branch, causing too slow balancing.

I didn't see that, but it's impact is only that a busy cpu is stealing
at most one task from another node, otherwise the idle=1 leads to more
aggressive balancing.

> > From these results I would prefer to either leave the numa scheduler as
> > it is or to introduce an IDLE_NODEBALANCE_TICK and a
> > BUSY_NODEBALANCE_TICK instead of just having one NODE_REBALANCE_TICK
> > which balances very rarely.
>
> agreed, i've attached the -B0 patch that does this. The balancing rates
> are 1 msec, 2 msec, 200 and 400 msec (idle-local, idle-global, busy-local,
> busy-global).

This looks good! I'll see if I can rerun the tests today, anyway I'm
more optimistic about this version.

Regards,
Erich