Re: [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb()
From: Linus Torvalds
Date: Mon Nov 17 2014 - 15:52:23 EST
On Mon, Nov 17, 2014 at 9:18 AM, Alexander Duyck
> 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.
Ugh. I absolutely despise the name.
It's not "fast". It's just limited. It's the same as "smp_*mb()", in
that it works on cacheable memory, but it actually stays around even
for non-SMP builds.
So I think the name is actively misleading.
Naming should be about what it does, not about some kind of PR thing
that confuses people into thinking it's "better".
Maybe "dma_*mb()" would be acceptable, and ends up having the same
naming convention as "smb_*mb()", and explains what it's about.
And yes, in the same spirit, it would probably be good to try to
eventually get rid of the plain "*mb()" functions, and perhaps call
them "mmio_*mb()" to clarify that they are about ordering memory wrt
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