Re: [PATCH v5 2/4] arch: Add lightweight memory barriers dma_rmb() and dma_wmb()

Benjamin Herrenschmidt
2014-11-25T23:17:30Z

On Tue, 2014-11-18 at 17:24 -0800, Alexander Duyck wrote:
> There are a number of situations where the mandatory barriers rmb() and
> wmb() are used to order memory/memory operations in the device drivers
> and those barriers are much heavier than they actually need to be. For
> example in the case of PowerPC wmb() calls the heavy-weight sync
> instruction when for coherent memory operations all that is really needed
> is an lsync or eieio instruction.
> .../...

For powerpc:

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>