From: Christoph Hellwig <hch@infradead.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>,
Robin Murphy <robin.murphy@arm.com>,
Tomasz Figa <tfiga@chromium.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Pawel Osciak <pawel@osciak.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
corbet@lwn.net, akpm@linux-foundation.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/3] common: DMA-mapping: add DMA_ATTR_NOHUGEPAGE attribute
Date: Fri, 8 Jan 2016 05:42:01 -0800 [thread overview]
Message-ID: <20160108134201.GA20665@infradead.org> (raw)
In-Reply-To: <1452213405-22942-3-git-send-email-dianders@chromium.org>
On Thu, Jan 07, 2016 at 04:36:44PM -0800, Douglas Anderson wrote:
> This patch adds the DMA_ATTR_NOHUGEPAGE attribute to the DMA-mapping
> subsystem.
>
> This attribute can be used as a hint to the DMA-mapping subsystem that
> it's likely not worth it to try to allocation large pages behind the
> scenes. Large pages are likely to make an IOMMU TLB work more
> efficiently but may not be worth it. See the Documentation contained in
> this patch for more details about this attribute and when to use it.
>
> Note that the name of the hint (DMA_ATTR_NOHUGEPAGE) is based on the
> name MADV_NOHUGEPAGE, which has the same meaning. If we have expected
> users, we could also add MADV_HUGEPAGE which has the opposite meaning of
> this hint.
A user of this features seems to be missing in the series. Please don't
add any clutter with unclear usage to the kernel unless there is a real
need which can be deonstrated in form of patches and numbers.
next prev parent reply other threads:[~2016-01-08 13:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-08 0:36 [PATCH v4 0/3] dma-mapping: Patches for speeding up allocation Douglas Anderson
2016-01-08 0:36 ` Douglas Anderson
2016-01-08 0:36 ` [PATCH v4 1/3] ARM: dma-mapping: Optimize allocation Douglas Anderson
2016-01-08 0:36 ` Douglas Anderson
2016-01-08 0:36 ` [PATCH v4 2/3] common: DMA-mapping: add DMA_ATTR_NOHUGEPAGE attribute Douglas Anderson
2016-01-08 13:10 ` Robin Murphy
2016-01-08 23:04 ` Doug Anderson
2016-01-08 13:35 ` Russell King - ARM Linux
2016-01-08 23:05 ` Doug Anderson
2016-01-08 23:18 ` Russell King - ARM Linux
2016-01-08 23:31 ` Doug Anderson
2016-01-09 7:55 ` Christoph Hellwig
2016-01-09 16:24 ` Tomasz Figa
2016-01-08 13:42 ` Christoph Hellwig [this message]
2016-01-08 23:05 ` Doug Anderson
2016-01-09 7:54 ` Christoph Hellwig
2016-01-08 0:36 ` [PATCH v4 3/3] ARM: dma-mapping: Use DMA_ATTR_NOHUGEPAGE hint to optimize allocation Douglas Anderson
2016-01-08 0:36 ` Douglas Anderson
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