From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: Speeding up dma_unmap
Date: Wed, 27 Jan 2016 18:09:45 +0000 [thread overview]
Message-ID: <20160127180944.GZ10826@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20160127160630.GQ14823@e104818-lin.cambridge.arm.com>
On Wed, Jan 27, 2016 at 04:06:30PM +0000, Catalin Marinas wrote:
> On Wed, Jan 27, 2016 at 01:23:27PM +0100, Arnd Bergmann wrote:
> > up reading cache lines back in randomly on a speculative prefetch,
> > but as far as I can tell, the Cortex-A8 (or A5/A7) won't do that.
>
> Are you sure about A5 and A7? I'm not even sure about the A8 but there
> are good chances that A7 and A5 do speculative prefetches.
I thought when I was re-implementing the DMA API on ARM (which was
around early v7 times) that there were CPUs that did speculative
prefetching, which included the A8. I seem to remember it was pretty
urgent to have the DMA API fixed for _any_ ARMv7 CPU because of the
speculative prefetching.
--
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next prev parent reply other threads:[~2016-01-27 18:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-27 8:32 Speeding up dma_unmap Jason Holt
2016-01-27 11:22 ` Ard Biesheuvel
2016-01-27 12:23 ` Arnd Bergmann
2016-01-27 16:06 ` Catalin Marinas
2016-01-27 18:09 ` Russell King - ARM Linux [this message]
2016-01-28 10:31 ` Catalin Marinas
2016-01-28 11:20 ` Arnd Bergmann
2016-01-28 11:49 ` Catalin Marinas
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