> On Wed, 30 Jan 2002, Rusty Russell wrote:
> > In message <Pine.LNX.email@example.com> you write:
> > > Nearly as good would be replacing the current logic for figuring out the
> > > current processor id through current with logic to access the per-cpu
> > > data. The primary use of that id is indexing that data anyway.
> > And if you'd been reading this thread, you would have already seen
> > this idea, and if you'd read the x86 code, you'd have realised that
> > the tradeoff is arch-specific.
> Looking closer, I've found an issue with your patch related to the above,
> so I think it bears closer examination.
Looking closer again (and not at 1am), I see I missed this line in reading
your patch, sorry:
+#define this_cpu(var) per_cpu(var,smp_processor_id())
I still think that tracking per_cpu_offset in task struct to eventually
replace current->processor is a win. Basically everyone except Sparc goes
through current anyway for smp_processor_id and Sparc caches current in a
register. Please elucidate your reference to "arch-specific tradeoffs".
Also, it'd be nice to unmap the original copy of the area or at least
poison it to catch silent references to var without going through
this_cpu, which will probably prove very hard to find. If there were a way
to do this at the C source level and catch such things at compile time,
that'd be even better, but I can't see a way to do it without grotty
-- "Love the dolphins," she advised him. "Write by W.A.S.T.E.."
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to firstname.lastname@example.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/