On Wed, Jun 10, 2015 at 09:00:31AM -0700, Dan Williams wrote: > > So sg_phys() turns out to be 'page_to_phys(sg_page(s)) + s->offset', > > which makes the above statement to: > > > > page_to_phys(sg_page(s)) + s->offset - s->offset; > > > > The compiler will probably optimize that away, but it still doesn't look > > like an improvement. > > The goal is to eventually stop leaking struct page deep into the i/o > stack. Anything that relies on being able to retrieve a struct page > out of an sg entry needs to be converted. I think we need a new > helper for this case "sg_phys_aligned()?". You still have a reference to a struct page, because sg_phys() calls sg_page() too. If you want to get rid of sg_page() something like sg_pfn() migth be a more workable solution than sg_phys_(page_)aligned. But maybe I am just missing the bigger scope of this, so I agree with Russell that it is better so see a patch series which shows the direction you want to go with this. Joerg -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
