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

Mark Glines
2007-04-18T18:14:32Z

On Wed, 18 Apr 2007 10:22:59 -0700 (PDT)
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> So if you have 2 users on a machine running CPU hogs, you should
> *first* try to be fair among users. If one user then runs 5 programs,
> and the other one runs just 1, then the *one* program should get 50%
> of the CPU time (the users fair share), and the five programs should
> get 10% of CPU time each. And if one of them uses two threads, each
> thread should get 5%.

This sounds great, to me.

One minor question: is it even possible to be completely fair on SMP?
For instance, if you have a 2-way SMP box running 3 applications, one of
which has 2 threads, will the threaded app have an advantage here? (The
current system seems to try to keep each thread on a specific CPU, to
reduce cache thrashing, which means threads and processes alike each
get 50% of the CPU.)

Mark