From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: Alexander Duyck <alexander.h.duyck@redhat•com>
Cc: linux-arch@vger•kernel.org, netdev@vger•kernel.org,
linux-kernel@vger•kernel.org, mathieu.desnoyers@polymtl•ca,
peterz@infradead•org, heiko.carstens@de•ibm.com,
mingo@kernel•org, mikey@neuling•org, linux@arm•linux.org.uk,
donald.c.skidmore@intel•com, matthew.vick@intel•com,
geert@linux-m68k•org, jeffrey.t.kirsher@intel•com,
romieu@fr•zoreil.com, paulmck@linux•vnet.ibm.com,
nic_swsd@realtek•com, will.deacon@arm•com,
michael@ellerman•id.au, tony.luck@intel•com,
torvalds@linux-foundation•org, oleg@redhat•com,
schwidefsky@de•ibm.com, fweisbec@gmail•com, davem@davemloft•net
Subject: Re: [PATCH v5 2/4] arch: Add lightweight memory barriers dma_rmb() and dma_wmb()
Date: Wed, 26 Nov 2014 10:15:28 +1100 [thread overview]
Message-ID: <1416957328.5089.17.camel@kernel.crashing.org> (raw)
In-Reply-To: <20141119012400.9563.21117.stgit@ahduyck-server>
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>
next prev parent reply other threads:[~2014-11-25 23:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-19 1:23 [PATCH v5 0/4] arch: Add lightweight memory barriers for coherent memory access Alexander Duyck
2014-11-19 1:23 ` [PATCH v5 1/4] arch: Cleanup read_barrier_depends() and comments Alexander Duyck
2014-11-19 1:24 ` [PATCH v5 2/4] arch: Add lightweight memory barriers dma_rmb() and dma_wmb() Alexander Duyck
2014-11-25 14:01 ` Will Deacon
2014-11-25 16:26 ` Alexander Duyck
2014-11-26 16:04 ` Will Deacon
2014-11-25 23:15 ` Benjamin Herrenschmidt [this message]
2014-11-19 1:24 ` [PATCH v5 3/4] r8169: Use dma_rmb() and dma_wmb() for DescOwn checks Alexander Duyck
2014-11-19 1:24 ` [PATCH v5 4/4] fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads Alexander Duyck
2014-11-19 1:28 ` Jeff Kirsher
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