Re: [Lse-tech] Re: [PATCH for 2.5] preemptible kernel

[Rusty Russell]

In message <OF42269F5F.CDF56B0F-ON88256A27.0083566F@LocalDomain> you write:
> > Already preempted tasks.
> 
> But if you are suppressing preemption in all read-side critical sections,
> then wouldn't any already-preempted tasks be guaranteed to -not- be in
> a read-side critical section, and therefore be guaranteed to be unaffected
> by the update (in other words, wouldn't such tasks not need to be waited
> for)?

Ah, if you want to inc and dec all the time, yes.  But even if the
performance isn't hurt, it's unneccessary, and something else people
have to remember to do.

Simplicity is very nice.  And in the case of module unload, gives us
the ability to avoid the distinction between "am I calling into a
module?" and "is this fixed in the kernel?" at runtime.  A very good
thing 8)

Rusty.
--
Premature optmztion is rt of all evl. --DK