netdev - Re: [PATCH v5 intel-next 2/9] ice: move ice_container_type onto ice_ring

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Date:   Mon, 16 Aug 2021 20:39:33 +0200
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     "Creeley, Brett" <brett.creeley@...el.com>
Cc:     "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "bjorn@...nel.org" <bjorn@...nel.org>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Lobakin, Alexandr" <alexandr.lobakin@...el.com>,
        "joamaki@...il.com" <joamaki@...il.com>,
        "toke@...hat.com" <toke@...hat.com>
Subject: Re: [PATCH v5 intel-next 2/9] ice: move ice_container_type onto
 ice_ring_container

On Mon, Aug 16, 2021 at 05:51:06PM +0100, Creeley, Brett wrote:
> > -----Original Message-----
> > From: Fijalkowski, Maciej <maciej.fijalkowski@...el.com>
> > Sent: Saturday, August 14, 2021 7:08 AM
> > To: intel-wired-lan@...ts.osuosl.org
> > Cc: netdev@...r.kernel.org; bpf@...r.kernel.org; davem@...emloft.net; Nguyen, Anthony L <anthony.l.nguyen@...el.com>;
> > kuba@...nel.org; bjorn@...nel.org; Karlsson, Magnus <magnus.karlsson@...el.com>; Brandeburg, Jesse
> > <jesse.brandeburg@...el.com>; Lobakin, Alexandr <alexandr.lobakin@...el.com>; joamaki@...il.com; toke@...hat.com; Creeley,
> > Brett <brett.creeley@...el.com>; Fijalkowski, Maciej <maciej.fijalkowski@...el.com>
> > Subject: [PATCH v5 intel-next 2/9] ice: move ice_container_type onto ice_ring_container
> >
> > Currently ice_container_type is scoped only for ice_ethtool.c. Next
> > commit that will split the ice_ring struct onto Rx/Tx specific ring
> > structs is going to also modify the type of linked list of rings that is
> > within ice_ring_container. Therefore, the functions that are taking the
> > ice_ring_container as an input argument will need to be aware of a ring
> > type that will be looked up.
> >
> > Embed ice_container_type within ice_ring_container and initialize it
> > properly when allocating the q_vectors.
> >
> > Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
> > ---
> >  drivers/net/ethernet/intel/ice/ice_base.c    |  2 ++
> >  drivers/net/ethernet/intel/ice/ice_ethtool.c | 36 ++++++++------------
> >  drivers/net/ethernet/intel/ice/ice_txrx.h    |  6 ++++
> >  3 files changed, 23 insertions(+), 21 deletions(-)
> 
> <snip>
> 
> > +enum ice_container_type {
> > +     ICE_RX_CONTAINER,
> > +     ICE_TX_CONTAINER,
> > +};
> > +
> >  struct ice_ring_container {
> >       /* head of linked-list of rings */
> >       struct ice_ring *ring;
> > @@ -347,6 +352,7 @@ struct ice_ring_container {
> >       u16 itr_setting:13;
> >       u16 itr_reserved:2;
> >       u16 itr_mode:1;
> > +     enum ice_container_type type;
> 
> It may not matter, but should you make sure
> the size of "type" doesn't negativelly affect this
> structure?

Seems that it doesn't matter.

Before:
struct ice_ring_container {
        struct ice_ring *          ring;                 /*     0     8 */
        struct dim                 dim;                  /*     8   120 */

        /* XXX last struct has 2 bytes of padding */

        /* --- cacheline 2 boundary (128 bytes) --- */
        u16                        itr_idx;              /*   128     2 */
        u16                        itr_setting:13;       /*   130: 0  2 */
        u16                        itr_reserved:2;       /*   130:13  2 */
        u16                        itr_mode:1;           /*   130:15  2 */

        /* size: 136, cachelines: 3, members: 6 */
        /* padding: 4 */
        /* paddings: 1, sum paddings: 2 */
        /* last cacheline: 8 bytes */


After:
struct ice_ring_container {
        union {
                struct ice_rx_ring * rx_ring;            /*     0     8 */
                struct ice_tx_ring * tx_ring;            /*     0     8 */
        };                                               /*     0     8 */
        struct dim                 dim;                  /*     8   120 */

        /* XXX last struct has 2 bytes of padding */

        /* --- cacheline 2 boundary (128 bytes) --- */
        u16                        itr_idx;              /*   128     2 */
        u16                        itr_setting:13;       /*   130: 0  2 */
        u16                        itr_reserved:2;       /*   130:13  2 */
        u16                        itr_mode:1;           /*   130:15  2 */
        enum ice_container_type    type;                 /*   132     4 */

        /* size: 136, cachelines: 3, members: 7 */
        /* paddings: 1, sum paddings: 2 */
        /* last cacheline: 8 bytes */

Still 3 cachelines and same sizes.


> 
> >  };
> >
> >  struct ice_coalesce_stored {
> > --
> > 2.20.1
>