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To: Yuanhan Liu <yuanhan.liu@linux.intel.com>, dev@dpdk.org
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From: Olivier Matz <olivier.matz@6wind.com>
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Date: Tue, 8 Nov 2016 09:43:14 +0100
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Subject: Re: [dpdk-dev] [PATCH v2] net/virtio: cache Rx/Tx offload ability
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Hi Yuanhan,

On 11/04/2016 03:29 PM, Yuanhan Liu wrote:
> It's not a good idea to do the check of whether Rx/Tx offload is
> enabled at the data path. Instead, we could do the check at init
> stage and store the result, so that we could avoid the check again
> and again at the critical datapath.
> 
> Cc: Olivier Matz <olivier.matz@6wind.com>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> ---
> v2: - rebase on top of the bug fix patches
>     - define rx/tx_offload as uint8_t instead of int
> 
>  drivers/net/virtio/virtio_ethdev.c | 19 +++++++++++++++++++
>  drivers/net/virtio/virtio_pci.h    |  2 ++
>  drivers/net/virtio/virtio_rxtx.c   | 31 +++++--------------------------
>  3 files changed, 26 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 1505f67..2adae58 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -1188,6 +1188,22 @@ rx_func_get(struct rte_eth_dev *eth_dev)
>  		eth_dev->rx_pkt_burst = &virtio_recv_pkts;
>  }
>  
> +static inline int
> +rx_offload_enabled(struct virtio_hw *hw)
> +{
> +	return vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_CSUM) ||
> +		vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO4) ||
> +		vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO6);
> +}
> +
> +static inline int
> +tx_offload_enabled(struct virtio_hw *hw)
> +{
> +	return vtpci_with_feature(hw, VIRTIO_NET_F_CSUM) ||
> +		vtpci_with_feature(hw, VIRTIO_NET_F_HOST_TSO4) ||
> +		vtpci_with_feature(hw, VIRTIO_NET_F_HOST_TSO6);
> +}

Do we need these functions to be inlined?

It looks better to do like this, but out of curiosity, do you see a
performance improvement?

Regards,
Olivier