From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Doug Anderson <dianders@chromium.org>
Cc: 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>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@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 23:18:06 +0000 [thread overview]
Message-ID: <20160108231806.GP19062@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAD=FV=WnxzvSYFb5cWVLR7O_PRw8niENDg2DXLX+o0F6FH-E7w@mail.gmail.com>
On Fri, Jan 08, 2016 at 03:05:13PM -0800, Doug Anderson wrote:
> 1. I have to go and touch all existing DMA-mapping code to set
> DMA_ATTR_HUGE_PAGE. That will be a big patchset and touch more code,
> making it more likely to break something.
...
Indeed, I was actually thinking of a positive "prefer/only use/force
smaller pages" thing rather than "allow huge pages" as a way to get
rid of the "no huge pages" negative as a way to get around that.
It has the same meaning when set as DMA_ATTR_NO_HUGE_PAGE but
avoids the problem of wondering what
!dma_get_attr(DMA_ATTR_NO_HUGE_PAGE, attrs)
means.
I wasn't thinking of DMA_ATTR_HUGE_PAGE as that would certainly be
wrong when CONFIG_HAVE_DMA_ATTRS is disabled (when dma_get_attr()
always returns 0.)
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2016-01-08 23:20 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 [this message]
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
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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