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Date: Mon, 17 Nov 2014 12:52:17 -0800 From: Linus Torvalds <torvalds@...ux-foundation.org> To: Alexander Duyck <alexander.h.duyck@...hat.com> Cc: "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>, Network Development <netdev@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>, Peter Zijlstra <peterz@...radead.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Heiko Carstens <heiko.carstens@...ibm.com>, Ingo Molnar <mingo@...nel.org>, Michael Neuling <mikey@...ling.org>, Russell King - ARM Linux <linux@....linux.org.uk>, donald.c.skidmore@...el.com, matthew.vick@...el.com, Geert Uytterhoeven <geert@...ux-m68k.org>, Jeff Kirsher <jeffrey.t.kirsher@...el.com>, Francois Romieu <romieu@...zoreil.com>, Paul McKenney <paulmck@...ux.vnet.ibm.com>, nic_swsd@...ltek.com, Will Deacon <will.deacon@....com>, Michael Ellerman <michael@...erman.id.au>, Tony Luck <tony.luck@...el.com>, Oleg Nesterov <oleg@...hat.com>, Martin Schwidefsky <schwidefsky@...ibm.com>, Frédéric Weisbecker <fweisbec@...il.com>, David Miller <davem@...emloft.net> Subject: Re: [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb() On Mon, Nov 17, 2014 at 9:18 AM, Alexander Duyck <alexander.h.duyck@...hat.com> 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. 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 mmio. Hmm? Linus -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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