Re: [PATCH] Load balancing problem in 2.6.2-mm1

[Nick Piggin]

Martin J. Bligh wrote:

> > > It's the classic fairness vs throughput thing we've argued about before.
> > > Most workloads don't have that static a number of processes, but it 
> > > probably does need to do it if the imbalance is persistent ... but much
> > > more reluctantly than normal balancing. See the patch I sent out a bit
> > > earlier to test it - that may be *too* extreme in the other direction,
> > > but it should confirm what's going on, at least.
> > Yep. I've argued for fairness here, and that is presently what
> > we get. Between nodes the threshold should probably be higher
> > though.
>
> OK, but do you agree that the rate we rebalance things like 2 vs 1 should
> be slower than the rate we rebalance 3 vs 1 ? Fairness is only relevant
> over a long term imbalance anyway, so there should be a big damper on
> "fairness only" rebalances.

Well presently it happens at the same rate. This isn't bad though,
because you just use the more conservative rate. Its probably not
worth distinguishing the two cases.

If a CPU becomes idle, it will attempt to balance immediately.

> Moreover, as Rick pointed out, it's particularly futile over idle cpus ;-)

I don't follow...

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/