From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dey, Souvik" Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio Date: Fri, 23 Sep 2016 15:17:37 +0000 Message-ID: References: <20160921231147.26820-1-sodey@sonusnet.com> <20160921162213.4b79d1ce@xeon-e3> <20160921184505.584367ef@xeon-e3> <20160923075320.GY23158@yliu-dev.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "dev@dpdk.org" To: "Kavanagh, Mark B" , Yuanhan Liu , Stephen Hemminger Return-path: Received: from NAM02-SN1-obe.outbound.protection.outlook.com (mail-sn1nam02on0080.outbound.protection.outlook.com [104.47.36.80]) by dpdk.org (Postfix) with ESMTP id 8C98428FD for ; Fri, 23 Sep 2016 17:17:39 +0200 (CEST) In-Reply-To: Content-Language: en-US List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Liu/Mark/Stephen, I have tried to modify the code with all of your latest comme= nts. Do let me know if this looks fine or you have more comments. Changes done : -- max frame ize is compare to VIRTIO_MAX_RX_PKTLEN instead of dev_info.max= _rx_pktlen -- removed the CRC_LEN from the ether_len calculation and added the merge r= x buf hdr len. ether_hdr_len =3D ETHER_HDR_LEN + VLAN_TAG_SIZE + hw->vtnet_= hdr_size -- Still retained the VLAN Size as the worst case scenario. -- drivers/net/virtio/virtio_ethdev.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio= _ethdev.c index 423c597..1dbfea6 100644 --- a/drivers/net/virtio/virtio_ethdev.c +++ b/drivers/net/virtio/virtio_ethdev.c @@ -653,12 +653,20 @@ virtio_dev_allmulticast_disable(struct rte_eth_dev *d= ev) PMD_INIT_LOG(ERR, "Failed to disable allmulticast"); } +#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 virtio_hw *hw =3D dev->data->dev_private; + uint32_t ether_hdr_len =3D ETHER_HDR_LEN + VLAN_TAG_SIZE + hw-= >vtnet_hdr_size; + uint32_t frame_size =3D mtu + ether_hdr_len; + + if (mtu < ETHER_MIN_MTU || frame_size > VIRTIO_MAX_RX_PKTLEN )= { + PMD_INIT_LOG(ERR, "MTU should be between %d and= %d\n", + ETHER_MIN_MTU, VIRTIO_MAX_RX_PKTL= EN); + return -EINVAL; + } + return 0; +} /* * dev_ops for virtio, bare necessities for basic operation */ @@ -677,7 +685,6 @@ static const struct eth_dev_ops virtio_eth_dev_ops =3D = { .allmulticast_enable =3D virtio_dev_allmulticast_enable, .allmulticast_disable =3D virtio_dev_allmulticast_disable, + .mtu_set =3D virtio_mtu_set, .dev_infos_get =3D virtio_dev_info_get, .stats_get =3D virtio_dev_stats_get, .xstats_get =3D virtio_dev_xstats_get, -- Please do let me know if this looks good to you all. Thanks -- Regards, Souvik -----Original Message----- From: Kavanagh, Mark B [mailto:mark.b.kavanagh@intel.com] Sent: Friday, September 23, 2016 5:08 AM To: Yuanhan Liu ; Stephen Hemminger Cc: Dey, Souvik ; dev@dpdk.org Subject: RE: [PATCH v6] net/virtio: add set_mtu in virtio >Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio > >On Wed, Sep 21, 2016 at 06:45:05PM -0700, Stephen Hemminger wrote: >> On Thu, 22 Sep 2016 00:08:38 +0000 >> "Dey, Souvik" > wrote: >> >> > Answers inline. >> > >> > -- >> > Regards, >> > Souvik >> > >> > -----Original Message----- >> > From: Stephen Hemminger [mailto:stephen@networkplumber.org] >> > Sent: Wednesday, September 21, 2016 7:22 PM >> > To: Dey, Souvik > >> > Cc: mark.b.kavanagh@intel.com; yuanh= an.liu@linux.intel.com; >> > dev@dpdk.org >> > Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio >> > >> > On Wed, 21 Sep 2016 19:11:47 -0400 >> > Dey > 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 =3D ETHER_HDR_LEN + ETHER_CRC_LEN + V= LAN_TAG_SIZE; >> > > + uint32_t frame_size =3D mtu + ether_hdr_len; >> > > + >> > > + virtio_dev_info_get(dev, &dev_info); >> > > + >> > > + if (mtu < ETHER_MIN_MTU || frame_size > dev_info.max_rx_pktl= en) { >> > > + 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 w= ant >> > is to access the max packet length. Since max_rx_pktlen is always >> > VIRTIO_MAX_RX_PKTLEN, please just use that. >> > [Dey, Souvik] I am using the virtio_dev_info_get as in future >> > can/may support the >max_rx_pktlen as a variable to be set by the application. This will >keep the changes future proof. As we need to support till 65535 instead of= 9728 as the linux does. >> >> Fine, then just dereference hw->rx_max_pktlen. Driver code can/should >> reference its own data directly. > >Dey, maybe you could just use VIRTIO_MAX_RX_PKTLEN here, like what you >did in early versions. > >> > >> > 2. Defining VLAN_TAG_SIZE is irrelevant if doing vlan offload. >> > [Dey, Souvik] vlan offload is not mandatory. Se again still have >> > vlan being sent up to >the application. In that case we need to consider the vlan length in the E= thernet size. >> >> The code needs to handle both vlan offload (or not), correctly. You >> are assuming the worst case here. > >I think we are fine here to assume worst case. > >> > >> > 3. Virtio doesn't insert CRC, therefore CRC_LEN is irrelevant >> > [Dey, Souvik] I am not sure of this. Mark commented earlier to conside= r this length too. >Mark what do you suggest ? >> >> Actually, the thing that matters is the size of the merge rx buf header,= not the CRC. > >Right. My comments were based on my experience with DPDK ethdev PMDs - Stephen and= Yuanhan have much more experience with virtio, so I'd go with their sugges= tion. > > --yliu >> >> The patch is still buggy. >>