Re: [patch] HT scheduler, sched-2.5.68-B2

Martin J. Bligh
2003-04-24T22:38:43Z

> Sorry if I misunderstand, but if HT is present, I would think that you
> would want to start the child of a fork on the same runqueue, because the
> cache is loaded, and to run the child first because in many cases the
> child will do and exac. At that point it is probable that the exec'd
> process run on another CPU would leave the cache useful to the parent.
>
> I fully admit that this is "seems to me" rather than measured, but
> protecting the cache is certainly a good thing in general.

We don't do balance on exec for SMP. I think we should ;-)
AFAIK, fork always stays on the same runqueue anyway.

>> The key is that we want to agressively steal when
>> nr_active(remote) - nr_active(idle) > 1 ... not > 0.
>> This will implicitly *never* happen on non HT machines, so it seems
>> like a nice algorithm ... ?
>
> Is it really that simple?

Well, *I* think so (obviously) ;-)
Feel free to poke holes in the argument ...

M.