On (21/02/16 09:49), Christoph Hellwig wrote: > > When working on the videobuf2 integration with Sergey I noticed that > > we always pass 0 as DMA attrs here, which removes the ability for > > drivers to use DMA_ATTR_ALLOC_SINGLE_PAGES. > > > > It's quite important from a system stability point of view, because by > > default the iommu_dma allocator would prefer big order allocations for > > TLB locality reasons. For many devices, though, it doesn't really > > affect the performance, because of random access patterns, so single > > pages are good enough and reduce the risk of allocation failures or > > latency due to fragmentation. > > > > Do you think we could add the attrs parameter to the > > dma_alloc_noncontiguous() API? > > Yes, we could probably do that. I can cook a patch, unless somebody is already looking into it. -ss
