From: Stephen Hemminger <stephen@networkplumber.org>
To: Dey <sodey@sonusnet.com>
Cc: <mark.b.kavanagh@intel.com>, <yuanhan.liu@linux.intel.com>,
<dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v6] net/virtio: add set_mtu in virtio
Date: Wed, 21 Sep 2016 16:22:13 -0700 [thread overview]
Message-ID: <20160921162213.4b79d1ce@xeon-e3> (raw)
In-Reply-To: <20160921231147.26820-1-sodey@sonusnet.com>
On Wed, 21 Sep 2016 19:11:47 -0400
Dey <sodey@sonusnet.com> wrote:
>
> +
> +#define VLAN_TAG_SIZE 4 /* 802.3ac tag (not DMA'd) */
> +
> +static int virtio_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
> +{
> + struct rte_eth_dev_info dev_info;
> + uint32_t ether_hdr_len = ETHER_HDR_LEN + ETHER_CRC_LEN + VLAN_TAG_SIZE;
> + uint32_t frame_size = mtu + ether_hdr_len;
> +
> + virtio_dev_info_get(dev, &dev_info);
> +
> + if (mtu < ETHER_MIN_MTU || frame_size > dev_info.max_rx_pktlen) {
> + PMD_INIT_LOG(ERR, "MTU should be between %d and %d\n",
> + ETHER_MIN_MTU,
> + (dev_info.max_rx_pktlen - ether_hdr_len));
> + return -EINVAL;
> + }
> + return 0;
> +}
I am fine with the general idea of this patch but:
1. Calling virtio_dev_info_get is needlessly wasteful when all you want
is to access the max packet length. Since max_rx_pktlen is always
VIRTIO_MAX_RX_PKTLEN, please just use that.
2. Defining VLAN_TAG_SIZE is irrelevant if doing vlan offload.
3. Virtio doesn't insert CRC, therefore CRC_LEN is irrelevant
next prev parent reply other threads:[~2016-09-21 23:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 23:11 Dey
2016-09-21 23:22 ` Stephen Hemminger [this message]
2016-09-22 0:08 ` Dey, Souvik
2016-09-22 1:45 ` Stephen Hemminger
2016-09-22 2:29 ` Dey, Souvik
2016-09-23 7:53 ` Yuanhan Liu
2016-09-23 9:07 ` Kavanagh, Mark B
2016-09-23 15:17 ` Dey, Souvik
2016-09-26 3:21 ` Yuanhan Liu
2016-09-27 15:41 ` Dey, Souvik
2016-09-27 18:56 ` Stephen Hemminger
2016-09-27 20:44 ` Dey, Souvik
2016-09-27 23:11 ` Yuanhan Liu
2016-09-28 15:31 ` Dey, Souvik
2016-09-22 15:57 ` Stephen Hemminger
-- strict thread matches above, loose matches on Subject: below --
2016-09-21 21:10 Dey
2016-09-16 17:13 [dpdk-dev] [PATCH v5]net/virtio: add mtu set " souvikdey33
2016-09-22 13:56 ` [dpdk-dev] [PATCH v6] net/virtio: add set_mtu " Dey
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