On Sat, 2017-02-18 at 17:34 +0100, Jesper Dangaard Brouer wrote: > On Thu, 16 Feb 2017 14:36:41 -0800 > John Fastabend <john.fastab...@gmail.com> wrote: > > > On 17-02-16 12:41 PM, Alexander Duyck wrote: > > > So I'm in the process of working on enabling XDP for the Intel NICs > > > and I had a few questions so I just thought I would put them out here > > > to try and get everything sorted before I paint myself into a corner. > > > > > > So my first question is why does the documentation mention 1 frame per > > > page for XDP? > > Yes, XDP defines upfront a memory model where there is only one packet > per page[1], please respect that! > > This is currently used/needed for fast-direct recycling of pages inside > the driver for XDP_DROP and XDP_TX, _without_ performing any atomic > refcnt operations on the page. E.g. see mlx4_en_rx_recycle().
XDP_DROP does not require having one page per frame. (Look after my recent mlx4 patch series if you need to be convinced) Only XDP_TX is. This requirement makes XDP useless (very OOM likely) on arches with 64K pages.
