On Wed, 21 Sep 2016 11:50:06 -0700, Tom Herbert wrote:
> On Wed, Sep 21, 2016 at 11:45 AM, Jakub Kicinski <kubak...@wp.pl> wrote:
> > On Wed, 21 Sep 2016 10:39:40 -0700, Tom Herbert wrote:
> >> On Wed, Sep 21, 2016 at 10:26 AM, Jakub Kicinski <kubak...@wp.pl> wrote:
> >> > On Tue, 20 Sep 2016 17:01:39 -0700, Alexei Starovoitov wrote:
> >> >> > - Reduces the amount of code and complexity needed in drivers to
> >> >> > manage XDP
> >> >>
> >> >> hmm:
> >> >> 534 insertions(+), 144 deletions(-)
> >> >> looks like increase in complexity instead.
> >> >
> >> > and more to come to tie this with HW offloads.
> >> The amount of driver code did decrease with these patches:
> >> drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 64
> >> ++++----------------------
> >> drivers/net/ethernet/mellanox/mlx4/en_rx.c | 25 ++++------
> >> drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 1 -
> >> Minimizing complexity being added to drivers for XDP is critical since
> >> we basically asking every driver to replicate the function. This
> >> property also should also apply to HW offloads, the more complexity we
> >> can abstract out drivers into a common backend infrastructure the
> >> better for supporting across different drivers.
> > I'm in the middle of writing/testing XDP support for the Netronome's
> > driver and generic infra is very much appreciated ;) In my experience
> > the 50 lines of code which are required for assigning the programs and
> > freeing them aren't really a big deal, though.
> 50 lines in one driver is not a big deal, 50 lines in a hundred
> drivers is! I learned this lesson in BQL which was well abstracted out
> to be minimally invasive but we still saw many issues because of the
> pecularities of different drivers.
Agreed, I just meant to say that splitting rings and rewritting RX path
to behave differently for XDP vs non-XDP case is way more brain
consuming than a bit of boilerplate code so if anyone could solve those
two it would be much appreciated :) My main point was what I wrote
> > Let's also separate putting xdp_prog in netdevice/napi_struct from the
> > generic hook infra. All the simplifications to the driver AFAICS come
> > from the former. If everyone is fine with growing napi_struct we can do
> > that but IMHO this is not an argument for the generic infra :)