Re: [rfc][patch] i386: remove comment about barriers

[David Howells]

Nick Piggin <npiggin@xxxxxxx> wrote:

> [ This is true for x86's sfence/lfence, but raises a question about Linux's
> memory barriers. Does anybody expect that a sequence of smp_wmb and smp_rmb
> would ever provide a full smp_mb barrier? I've always assumed no, but I
> don't know if it is actually documented? ]

I think you have to assume that smp_wmb() only orders stores and write
barriers, and that smp_rmb() only orders reads and read barriers.

smp_mb() implies both smp_wmb() and smp_rmb(), but is greater than the
combination of the two.

David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/