On Thu, 13 Jun 2019 14:01:39 +0000, Maxim Mikityanskiy wrote: > On 2019-06-12 23:10, Jakub Kicinski wrote: > > On Wed, 12 Jun 2019 15:56:43 +0000, Maxim Mikityanskiy wrote: > >> The typical XDP memory scheme is one packet per page. Change the AF_XDP > >> frame size in libbpf to 4096, which is the page size on x86, to allow > >> libbpf to be used with the drivers with the packet-per-page scheme. > > > > This is slightly surprising. Why does the driver care about the bufsz? > > The classic XDP implementation supports only the packet-per-page scheme. > mlx5e implements this scheme, because it perfectly fits with xdp_return > and page pool APIs. AF_XDP relies on XDP, and even though AF_XDP doesn't > really allocate or release pages, it works on top of XDP, and XDP > implementation in mlx5e does allocate and release pages (in general > case) and works with the packet-per-page scheme. Yes, okay, I get that. But I still don't know what's the exact use you have for AF_XDP buffers being 4k.. Could you point us in the code to the place which relies on all buffers being 4k in any XDP scenario? > > You're not supposed to so page operations on UMEM pages, anyway. > > And the RX size filter should be configured according to MTU regardless > > of XDP state. > > Yes, of course, MTU is taken into account. > > > Can you explain? > > > >> Add a command line option -f to xdpsock to allow to specify a custom > >> frame size. > >> > >> Signed-off-by: Maxim Mikityanskiy <maximmi@xxxxxxxxxxxx> > >> Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxxxx> > >> Acked-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
