On 2023/8/17 19:43, Ilias Apalodimas wrote: >>>>>> >>>>>> In order to simplify the driver's work when using frag API >>>>>> this patch allows page_pool_alloc_frag() to call >>>>>> page_pool_alloc_pages() to return pages for those arches. >>>>> >>>>> Do we have any use cases of people needing this? Those architectures >>>>> should be long dead and although we have to support them in the >>>>> kernel, I don't personally see the advantage of adjusting the API to >>>>> do that. Right now we have a very clear separation between allocating >>>>> pages or fragments. Why should we hide a page allocation under a >>>>> frag allocation? A driver writer can simply allocate pages for those >>>>> boards. Am I the only one not seeing a clean win here? >>>> >>>> It is also a part of removing the per page_pool PP_FLAG_PAGE_FRAG flag >>>> in this patchset. >>> >>> Yes, that happens *because* of this patchset. I am not against the >>> change. In fact, I'll have a closer look tomorrow. I am just trying >>> to figure out if we really need it. When the recycling patches were >>> introduced into page pool we had a very specific reason. Due to the >>> XDP verifier we *had* to allocate a packet per page. That was >> >> Did you mean a xdp frame containing a frag page can not be passed to the >> xdp core? >> What is exact reason why the XDP verifier need a packet per page? >> Is there a code block that you can point me to? > > It's been a while since I looked at this, but doesn't __xdp_return() > still sync the entire page if the mem type comes from page_pool? Yes, I checked that too. It is supposed to sync the entire page if the mem type comes from page_pool, as it depend on the last freed frag to do the sync_for_device operation.
