Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory barrier (v5)

Paul E. McKenney
2010-01-13T15:58:56Z

On Tue, Jan 12, 2010 at 09:39:56PM -0800, Nicholas Miell wrote:
> On Tue, 2010-01-12 at 21:31 -0800, Paul E. McKenney wrote:
> > Why is it OK to ignore the developer's request for an expedited
> > membarrer()? The guy who expected the syscall to complete in a few
> > microseconds might not be so happy to have it take many milliseconds.
> > By the same token, the guy who specified non-expedited so as to minimally
> > disturb other threads in the system might not be so happy to see them
> > all be IPIed for no good reason. ;-)
> >
> > Thanx, Paul
>
> Because the behavior is still correct, even if it is slower than you'd
> expect. It doesn't really matter where the expedited flag goes, though,
> because every future kernel will understand it.

In a real-time application, no shortage of which run on Linux, "going
slower than you expect" is a bug, right?

Thanx, Paul