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From: Alessandro Rubini <rubini@gnudd.com>
To: federico.vaga@gmail.com
Cc: mchehab@redhat.com, m.szyprowski@samsung.com,
	mchehab@infradead.org, pawel@osciak.com, hans.verkuil@cisco.com,
	giancarlo.asnaghi@st.com, linux-media@vger.kernel.org,
	linux-kernel@vger.kernel.org, corbet@lwn.net,
	s.nawrocki@samsung.com
Subject: Re: [PATCH v3 2/4] videobuf2-dma-streaming: new videobuf2 memory allocator
Date: Mon, 7 Jan 2013 00:09:47 +0100	[thread overview]
Message-ID: <20130106230947.GA17979@mail.gnudd.com> (raw)
In-Reply-To: <3892735.vLSnhhCRFi@harkonnen>

> The problem is that on the sta2x11 architecture only the first 
> 512MB are available through the PCI bus, but the allocator can allocate memory 
> for DMA above this limit. By using GFP_DMA flags the allocation take place 
> under the 16MB so it works.

Still, you are not running the upstream allocator.  IIUC, you added a
"gfp_t" field in the platform data or somewhere, so the sta2x11 can
request GFP_DMA to be OR'd, while other users remain unaffected.  Will
you please submit the patch to achieve that?

> I cannot do performance test at the moment because I don't have the time, so I 
> cannot personally justify the presence of a new allocator.

I don't expect you'll see serious performance differences on the PC. I
think ARM users will have better benefits, due to the different cache
architecture.  You told me Jon measured meaningful figures on a Marvel
CPU.

> I will propose V4 patches soon.

thanks
/alessandro

  parent reply	other threads:[~2013-01-06 23:10 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-24 10:58 [PATCH v3 1/4] v4l: vb2: add prepare/finish callbacks to allocators Federico Vaga
2012-09-24 10:58 ` [PATCH v3 2/4] videobuf2-dma-streaming: new videobuf2 memory allocator Federico Vaga
2012-09-24 12:44   ` Marek Szyprowski
2012-12-04 16:04     ` Mauro Carvalho Chehab
2012-12-05 12:50       ` Federico Vaga
2012-12-05 14:25         ` Mauro Carvalho Chehab
2012-12-11 13:54           ` Federico Vaga
2012-12-18 14:41             ` Marek Szyprowski
2012-12-20 15:37               ` Federico Vaga
2013-01-01 12:52                 ` Mauro Carvalho Chehab
2013-01-03 16:13                   ` Federico Vaga
2013-01-04 13:30                     ` Federico Vaga
2013-01-06 17:04                       ` Federico Vaga
2013-01-06 23:09                       ` Alessandro Rubini [this message]
2013-01-07 19:40                         ` Jonathan Corbet
2013-01-07 20:15                           ` Mauro Carvalho Chehab
2013-01-08  6:50                             ` Marek Szyprowski
2013-01-08 14:31                               ` Jonathan Corbet
2013-01-09  7:48                                 ` Michael Olbrich
2012-09-24 10:58 ` [PATCH v3 3/4] sta2x11_vip: convert to videobuf2 and control framework Federico Vaga
2012-12-04 16:15   ` Mauro Carvalho Chehab
2012-12-05  1:12     ` Federico Vaga
2012-12-05 11:34       ` Mauro Carvalho Chehab
2012-12-05 12:24         ` Federico Vaga
2012-12-05 13:10           ` Mauro Carvalho Chehab
2012-12-05 13:27             ` Federico Vaga
2012-12-05 13:37               ` Mauro Carvalho Chehab
2012-12-05 13:45                 ` Federico Vaga
2012-12-06 18:59             ` Federico Vaga
2012-09-24 10:58 ` [PATCH v3 4/4] adv7180: remove {query/g_/s_}ctrl Federico Vaga
2012-09-24 12:46 ` [PATCH v3 1/4] v4l: vb2: add prepare/finish callbacks to allocators Marek Szyprowski
2012-09-25 15:04 ` Federico Vaga

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