On Thu, 2002-02-21 at 15:29, Linus Torvalds wrote:
>
> On 20 Feb 2002, Robert Love wrote:
> >
> > With a preemptive kernel, explicit conditional schedules when
> > preempt_count is zero are a waste of cycles and code size.
>
> Hmm.. Are there any other kind?
>
> Another way of saying this: how can a conditional schedule _ever_ be
> nothing but a waste of cycles and code size with preemption enabled?
>
> If the reason is the BKL, then I would much prefer those paths to be
> BKL-fixed, than have two different conditional schedules.
>
> In short, I'd rather get a patch that just unconditionally makes the
> conditional schedules no-ops with preemption enabled. That would seem to
> make a lot more sense.
I assume (and hope) the reason is always the BKL.
I would rather not eliminate any explicit reschedules from the kernel
for the preemptive kernel case only. That sort of defeats a purpose
(response improvement) of the kernel.
And I wholeheartedly agree that the situations where the BKL is held
should be handled and an ideal solution is to just not explicitly
schedule anywhere in the kernel with a preemptive kernel. But I suspect
this will involve a lot of dark magic wrt BKL locking semantics.
What do you have in mind?
Robert Love
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This archive was generated by hypermail 2b29 : Sat Feb 23 2002 - 21:00:36 EST