Re: Maximum frequency of re-scheduling (minimum time quantum ) que stio n

[Andrew Morton <akpm@osdl.org>]

Con Kolivas <kernel@kolivas.org> wrote:
>
> Andrew Morton writes:
> 
> > Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> >>
> >> However well tested your scheduler might be, it needs several
> >>  orders of magnitude more testing ;) Maybe the best we can hope
> >>  for is compile time selectable alternatives.
> > 
> > At this stage in the kernel lifecycle, for something as fiddly as the CPU
> > scheduler we really should be 100% driven by problem reporting.
> > 
> > If someone can identify a particular misbehaviour in the CPU scheduler then
> > they should put their editor away and work to produce a solid testcase. 
> > Armed with that, we can then identify the source of the particular problem.
> > 
> > It is at this point, and no earlier, that we can decide what an appropriate
> > solution is.  We then balance the risk of that solution against the severity
> > of the problem which it solves and make a decision as to whether to proceed.
> > 
> > Right now, the ratio of quality bug reporting to scheduler patching is
> > bizarrely small.
> 
> Is "for fun" not reason enough?

Sure.   "For 2.7" is a good reason, too.

> I'm still keeping an eye out for firm "behavioural" bug reports on 2.6 and 
> would discuss or address them.

OK, thanks.

> Seriously the only reason I went down the rewrite path was to address 
> complaints about the complexity of the current design. It was also an 
> opportunity to start implementing some requested features. I certainly have 
> never suggested it should even be considered for 2.6.

Yeah, I tend to think that the CPU scheduler is currently 90% good enough,
and does seem to have become rather opaque.

I wouldn't mind having a new "for fun" scheduler in -mm, except there's
ongoing futzing with the current one to be sorted out.