Re: [PATCH v3 2/4] videobuf2-dma-streaming: new videobuf2 memoryallocator
From: Alessandro Rubini
Date: Sun Jan 06 2013 - 18:10:41 EST
> 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
> I will propose V4 patches soon.
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