Re: [PATCH] cpuset and sched domains: sched_load_balance flag

Nick Piggin
2007-10-03T12:25:14Z

On Wednesday 03 October 2007 22:14, Paul Jackson wrote:
> > These are what I'm worried about, and things like kswapd, pdflush,
> > could definitely use a huge amount of CPU.
> >
> > If you are interested in hard partitioning the system, you most
> > definitely want these things to be balanced across the non-isolated
> > CPUs.
>
> But these guys are pinned anyway (or else they would already be moved
> into a smaller load balanced cpuset), so why waste time load balancing
> what can't move?

They're not pinned (kswapds are pinned to a node, but still). pdflush
is not pinned at all and can be dynamically created and destroyed. Ditto
for kjournald, as well as many others.

Basically: it doesn't feel like a satisfactory solution to brush these under
the carpet.

> And on some of the systems I care about, we don't want to load balance
> these guys; rather we go to great lengths to see that they don't run at
> all when we don't want them to.

Most smaller realtime partitioned systems will want to, I'd expect.