From: Christoph Hellwig <hch@infradead.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Nicolin Chen <nicoleotsuka@gmail.com>,
joro@8bytes.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/dma: Zero pages manually in a length of scatterlist
Date: Thu, 8 Nov 2018 23:45:10 -0800 [thread overview]
Message-ID: <20181109074510.GA27623@infradead.org> (raw)
In-Reply-To: <afdc0e33-db18-6ad9-61cd-919fe3df1b4e@arm.com>
On Tue, Nov 06, 2018 at 02:39:26PM +0000, Robin Murphy wrote:
> ...and I have some significant objections to that simplification which I
> plan to respond with ;)
>
> (namely that it defaults the whole higher-order page allocation business
> which will have varying degrees of performance impact on certain cases)
Well, please place your objection there. The behavior does match what
every other iommu-based dma ops implementation ouside of arm/arm64 does,
so there is some precedent for it to say the least. But if the only
current users objects I'll surely find a way to accomodate it, but a
good rationale including numbers would be useful to document it.
next prev parent reply other threads:[~2018-11-09 7:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 21:35 [PATCH] iommu/dma: Zero pages manually in a length of scatterlist Nicolin Chen
2018-11-02 16:54 ` Robin Murphy
2018-11-02 23:36 ` Nicolin Chen
2018-11-05 14:58 ` Christoph Hellwig
2018-11-06 14:39 ` Robin Murphy
2018-11-09 7:45 ` Christoph Hellwig [this message]
2018-11-06 18:27 ` Robin Murphy
2018-11-07 0:11 ` Nicolin Chen
2018-11-04 15:50 ` Christoph Hellwig
2018-11-06 23:46 ` Nicolin Chen
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