Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Nick Piggin
2007-04-17T07:12:04Z

On Mon, Apr 16, 2007 at 11:50:03PM -0700, Davide Libenzi wrote:
> On Tue, 17 Apr 2007, Nick Piggin wrote:
>
> > > All things are not equal; they all have different properties. I like
> >
> > Exactly. So we have to explore those properties and evaluate performance
> > (in all meanings of the word). That's only logical.
>
> I had a quick look at Ingo's code yesterday. Ingo is always smart to
> prepare a main dish (feature) with a nice sider (code cleanup) to Linus ;)
> And even this code does that pretty nicely. The deadline designs looks
> good, although I think the final "key" calculation code will end up quite
> different from what it looks now.
> I would suggest to thoroughly test all your alternatives before deciding.
> Some code and design may look very good and small at the beginning, but
> when you start patching it to cover all the dark spots, you effectively
> end up with another thing (in both design and code footprint).
> About O(1), I never thought it was a must (besides a good marketing
> material), and O(log(N)) *may* be just fine (to be verified, of course).

To be clear, I'm not saying O(logN) itself is a big problem. Type

plot [10:100] x with lines, log(x) with lines, 1 with lines

into gnuplot. I was just trying to point out that we need to evalute
things. Considering how long we've had this scheduler with its known
deficiencies, let's pick a new one wisely.