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

[Benjamin Herrenschmidt]

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@xxxxxxxxxxxxxxxxxxx>



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