On Wed, Oct 9, 2024 at 3:19 AM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
Hi Jakub,
Thanks a lot for your reviews!
> On Thu, 3 Oct 2024 16:06:15 +0000 Taehee Yoo wrote:
> > diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
> > index fdecdf8894b3..e9ef65dd2e7b 100644
> > --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
> > +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
> > @@ -829,12 +829,16 @@ static void bnxt_get_ringparam(struct net_device *dev,
> > if (bp->flags & BNXT_FLAG_AGG_RINGS) {
> > ering->rx_max_pending = BNXT_MAX_RX_DESC_CNT_JUM_ENA;
> > ering->rx_jumbo_max_pending = BNXT_MAX_RX_JUM_DESC_CNT;
> > - kernel_ering->tcp_data_split = ETHTOOL_TCP_DATA_SPLIT_ENABLED;
> > } else {
> > ering->rx_max_pending = BNXT_MAX_RX_DESC_CNT;
> > ering->rx_jumbo_max_pending = 0;
> > - kernel_ering->tcp_data_split = ETHTOOL_TCP_DATA_SPLIT_DISABLED;
> > }
> > +
> > + if (bp->flags & BNXT_FLAG_HDS)
> > + kernel_ering->tcp_data_split = ETHTOOL_TCP_DATA_SPLIT_ENABLED;
> > + else
> > + kernel_ering->tcp_data_split = ETHTOOL_TCP_DATA_SPLIT_DISABLED;
>
> This breaks previous behavior. The HDS reporting from get was
> introduced to signal to user space whether the page flip based
> TCP zero-copy (the one added some years ago not the recent one)
> will be usable with this NIC.
>
> When HW-GRO is enabled HDS will be working.
>
> I think that the driver should only track if the user has set the value
> to ENABLED (forced HDS), or to UKNOWN (driver default). Setting the HDS
> to disabled is not useful, don't support it.
Okay, I will remove the disable feature in a v4 patch.
Before this patch, hds_threshold was rx-copybreak value.
How do you think hds_threshold should still follow rx-copybreak value
if it is UNKNOWN mode?
I think hds_threshold need to follow new tcp-data-split-thresh value in
ENABLE/UNKNOWN and make rx-copybreak pure software feature.
But if so, it changes the default behavior.
How do you think about it?
>
> > ering->tx_max_pending = BNXT_MAX_TX_DESC_CNT;
> >
> > ering->rx_pending = bp->rx_ring_size;
> > @@ -854,9 +858,25 @@ static int bnxt_set_ringparam(struct net_device *dev,
> > (ering->tx_pending < BNXT_MIN_TX_DESC_CNT))
> > return -EINVAL;
> >
> > + if (kernel_ering->tcp_data_split != ETHTOOL_TCP_DATA_SPLIT_DISABLED &&
> > + BNXT_RX_PAGE_MODE(bp)) {
> > + NL_SET_ERR_MSG_MOD(extack, "tcp-data-split can not be enabled with XDP");
> > + return -EINVAL;
> > + }
>
> Technically just if the XDP does not support multi-buffer.
> Any chance we could do this check in the core?
I think we can access xdp_rxq_info with netdev_rx_queue structure.
However, xdp_rxq_info is not sufficient to distinguish mb is supported
by the driver or not. I think prog->aux->xdp_has_frags is required to
distinguish it correctly.
So, I think we need something more.
Do you have any idea?
