Re: [PATCH 3/4] x86,asm: Re-work smp_store_mb()
From: Peter Zijlstra
Date: Tue Oct 27 2015 - 20:11:17 EST
On Wed, Oct 28, 2015 at 06:33:56AM +0900, Linus Torvalds wrote:
> On Wed, Oct 28, 2015 at 4:53 AM, Davidlohr Bueso <dave@xxxxxxxxxxxx> wrote:
> > Note that this might affect callers that could/would rely on the
> > atomicity semantics, but there are no guarantees of that for
> > smp_store_mb() mentioned anywhere, plus most archs use this anyway.
> > Thus we continue to be consistent with the memory-barriers.txt file,
> > and more importantly, maintain the semantics of the smp_ nature.
> So with this patch, the whole thing becomes pointless, I feel. (Ok, so
> it may have been pointless before too, but at least before this patch
> it generated special code, now it doesn't). So why carry it along at
So I suppose this boils down to if: XCHG ends up being cheaper than
PeterA, any idea?
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/