Re: [ANNOUNCE][RFC] PlugSched-6.4 for 2.6.18-rc2

From: Peter Williams
Date: Wed Jul 26 2006 - 01:40:07 EST

Al Boldi wrote:
Peter Williams wrote:
Al Boldi wrote:
Peter Williams wrote:
Al Boldi wrote:
Peter Williams wrote:
Al Boldi wrote:
[bits deleted]

It may be really great, to allow schedulers perPid parent, thus
allowing the stacking of different scheduler semantics. This could
aid flexibility a lot.
I'm don't understand what you mean here. Could you elaborate?
i.e: Boot the kernel with spa_no_frills, then start X with spa_ws.
It's probably not a good idea to have different schedulers managing the
same resource. The way to do different scheduling per process is to
use the scheduling policy mechanism i.e. SCHED_FIFO, SCHED_RR, etc.
(possibly extended) within each scheduler. On the other hand, on an
SMP system, having a different scheduler on each run queue (or sub set
of queues) might be interesting :-).
What's wrong with multiple run-queues on UP?
A really high likelihood of starvation of some tasks.

Maybe you are thinking of running independent run-queues, in which case it would probably be unwise to run multiple RQs on a single CPU.

No. I'm thinking about different schedulers on a single run queue. I don't think that it's a good idea.

But I was more thinking of a run-queue of run-queues, with the masterRQ scheduling slaveRQs, each RQ possible running its own scheduling semantic.

I think that you need to think a bit harder about the consequences of such a system. The word "chaos" springs to mind.

Peter Williams pwil3058@xxxxxxxxxxxxxx

"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
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