From: "Dey, Souvik" <sodey@sonusnet.com>
To: "Kavanagh, Mark B" <mark.b.kavanagh@intel.com>,
Yuanhan Liu <yuanhan.liu@linux.intel.com>,
Stephen Hemminger <stephen@networkplumber.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v6] net/virtio: add set_mtu in virtio
Date: Fri, 23 Sep 2016 15:17:37 +0000 [thread overview]
Message-ID: <BN3PR03MB1494B23E8BBFB53B79EF4259DAC80@BN3PR03MB1494.namprd03.prod.outlook.com> (raw)
In-Reply-To: <DC5AD7FA266D86499789B1BCAEC715F85C71C19D@irsmsx105.ger.corp.intel.com>
Hi Liu/Mark/Stephen,
I have tried to modify the code with all of your latest comments. 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 rx buf hdr len. ether_hdr_len = 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 *dev)
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 = dev->data->dev_private;
+ uint32_t ether_hdr_len = ETHER_HDR_LEN + VLAN_TAG_SIZE + hw->vtnet_hdr_size;
+ uint32_t frame_size = 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_PKTLEN);
+ 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 = {
.allmulticast_enable = virtio_dev_allmulticast_enable,
.allmulticast_disable = virtio_dev_allmulticast_disable,
+ .mtu_set = virtio_mtu_set,
.dev_infos_get = virtio_dev_info_get,
.stats_get = virtio_dev_stats_get,
.xstats_get = 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 <yuanhan.liu@linux.intel.com>; Stephen Hemminger <stephen@networkplumber.org>
Cc: Dey, Souvik <sodey@sonusnet.com>; 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" <sodey@sonusnet.com<mailto:sodey@sonusnet.com>> 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 <sodey@sonusnet.com<mailto:sodey@sonusnet.com>>
>> > Cc: mark.b.kavanagh@intel.com<mailto:mark.b.kavanagh@intel.com>; yuanhan.liu@linux.intel.com<mailto:yuanhan.liu@linux.intel.com>;
>> > dev@dpdk.org<mailto:dev@dpdk.org>
>> > Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio
>> >
>> > On Wed, 21 Sep 2016 19:11:47 -0400
>> > Dey <sodey@sonusnet.com<mailto: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.
>> > [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 Ethernet 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 consider 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 suggestion.
>
> --yliu
>>
>> The patch is still buggy.
>>
next prev parent reply other threads:[~2016-09-23 15:17 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
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 [this message]
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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