On Tue, Feb 23, 2021 at 08:44:52AM -0800, Dan Williams wrote: > > The downside would be one extra lookup in dev_pagemap tree > > for other pgmap->types (P2P, FSDAX, PRIVATE). But just one > > per gup-fast() call. > > I'd guess a dev_pagemap lookup is faster than a get_user_pages slow > path. It should be measurable that this change is at least as fast or > faster than falling back to the slow path, but it would be good to > measure. What is the dev_pagemap thing doing in gup fast anyhow? I've been wondering for a while.. Jason
