From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
arnd@arndb.de, monstr@monstr.eu, dhowells@redhat.com,
broonie@linaro.org, paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH 00/18] Cross-architecture definitions of relaxed MMIO accessors
Date: Fri, 18 Apr 2014 07:36:58 +1000 [thread overview]
Message-ID: <1397770618.32730.81.camel@pasglop> (raw)
In-Reply-To: <20140417140036.GK11096@twins.programming.kicks-ass.net>
On Thu, 2014-04-17 at 16:00 +0200, Peter Zijlstra wrote:
> So the non-relaxed ops already imply the expensive I/O barrier (mmiowb?)
> and therefore, PPC can drop it from spin_unlock()?
We play a trick. We set a per-cpu flag in writeX and test it in unlock
before doing the barrier. Still better than having the barrier in every
MMIO at this stage for us.
Whether we want to change that with then new scheme ... we'll see.
> Also, I read mmiowb() as MMIO-write-barrier(), what do we have to
> order/contain mmio-reads?
>
> I have _0_ experience with MMIO, so I've no idea if ordering/containing
> reads is silly or not.
I will review the rest when I'm back from vacation (or maybe this
week-end).
Thanks Will for picking that up, it's long overdue :)
Cheers,
Ben.
next prev parent reply other threads:[~2014-04-17 21:37 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-17 13:44 [PATCH 00/18] Cross-architecture definitions of relaxed MMIO accessors Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 01/18] asm-generic: io: implement relaxed accessor macros as conditional wrappers Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 02/18] microblaze: io: remove dummy relaxed accessor macros Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-22 13:53 ` Michal Simek
2014-04-22 13:53 ` Michal Simek
2014-04-17 13:44 ` [PATCH 03/18] s390: io: remove dummy relaxed accessor macros for reads Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 04/18] xtensa: " Will Deacon
2014-04-17 13:44 ` [PATCH 05/18] alpha: io: implement relaxed accessor macros for writes Will Deacon
2014-04-17 13:44 ` [PATCH 06/18] frv: io: implement dummy " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 07/18] cris: " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-22 13:47 ` Jesper Nilsson
2014-04-22 13:47 ` Jesper Nilsson
2014-04-17 13:44 ` [PATCH 08/18] ia64: " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 09/18] m32r: " Will Deacon
2014-04-17 13:44 ` [PATCH 10/18] m68k: " Will Deacon
2014-04-17 16:07 ` Geert Uytterhoeven
2014-04-17 13:44 ` [PATCH 11/18] mn10300: " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 12/18] parisc: " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 13/18] powerpc: " Will Deacon
2014-04-17 13:44 ` [PATCH 14/18] sparc: " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 15/18] tile: " Will Deacon
2014-04-17 14:52 ` Chris Metcalf
2014-04-17 13:44 ` [PATCH 16/18] x86: " Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-22 16:08 ` Will Deacon
2014-05-21 1:53 ` Brian Norris
2014-05-21 9:22 ` Will Deacon
2014-04-17 13:44 ` [PATCH 17/18] documentation: memory-barriers: clarify relaxed io accessor semantics Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-17 13:44 ` [PATCH 18/18] asm-generic: io: define relaxed accessor macros unconditionally Will Deacon
2014-04-17 13:44 ` Will Deacon
2014-04-22 14:09 ` Michal Simek
2014-04-22 15:18 ` Will Deacon
2014-04-22 15:18 ` Will Deacon
2014-04-23 7:12 ` Michal Simek
2014-04-23 7:12 ` Michal Simek
2014-04-23 7:23 ` Sam Ravnborg
2014-04-23 7:23 ` Sam Ravnborg
2014-04-23 7:36 ` Michal Simek
2014-04-17 14:00 ` [PATCH 00/18] Cross-architecture definitions of relaxed MMIO accessors Peter Zijlstra
2014-04-17 14:15 ` Will Deacon
2014-04-17 14:15 ` Will Deacon
2014-04-17 21:36 ` Benjamin Herrenschmidt [this message]
2014-05-01 11:10 ` Will Deacon
2014-04-17 15:36 ` Sam Ravnborg
2014-04-17 15:47 ` Will Deacon
2014-04-17 19:15 ` Sam Ravnborg
2014-04-22 13:43 ` Will Deacon
2014-04-22 14:30 ` Sam Ravnborg
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