On Wed, Mar 05, 2025 at 12:43:02PM +0100, Hannes Reinecke wrote: > Oh, sure. But what annoys me: why do we have to care? > > When doing I/O _all_ data is stuffed into bvecs via > bio_add_page(), and after that information about the > origin is lost; any iteration on the bio will be a bvec > iteration. > Previously we could just do a bvec iteration, get a reference > for each page, and start processing. > Now suddenly the caller has to check if it's a slab page and don't > get a reference for that. Not only that, he also has to remember > to _not_ drop the reference when he's done. > And, of course, tracing get_page() and the corresponding put_page() > calls through all the layers. Networking needs to follow block's lead and STOP GETTING REFCOUNTS ON PAGES. That will speed up networking (eliminates two atomic operations per page). And of course, it will eliminate this hack in the MM. I think we do need to put this hack into the MM for now, but it needs to go away again as quickly as possible. What worries me is that nobody in networking has replied to this thread yet. Do they not care? Let's see if a subject line change will help with that.
