From: "Zhang, Qi Z" <qi.z.zhang@intel.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"Yigit, Ferruh" <ferruh.yigit@intel.com>,
"Stokes, Ian" <ian.stokes@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Cc: "stephen@networkplumber.org" <stephen@networkplumber.org>,
"Lu, Wenzhuo" <wenzhuo.lu@intel.com>,
"Xing, Beilei" <beilei.xing@intel.com>
Subject: Re: [dpdk-dev] [PATCH v2 6/7] net/e1000: set min and max MTU for igb devices
Date: Wed, 27 Mar 2019 07:02:18 +0000 [thread overview]
Message-ID: <039ED4275CED7440929022BC67E7061153355381@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB977258013656011B@irsmsx105.ger.corp.intel.com>
> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Wednesday, March 27, 2019 9:14 AM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Yigit, Ferruh
> <ferruh.yigit@intel.com>; Stokes, Ian <ian.stokes@intel.com>; dev@dpdk.org
> Cc: stephen@networkplumber.org; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Xing,
> Beilei <beilei.xing@intel.com>
> Subject: RE: [dpdk-dev] [PATCH v2 6/7] net/e1000: set min and max MTU for igb
> devices
>
>
>
> > -----Original Message-----
> > From: Ananyev, Konstantin
> > Sent: Tuesday, March 26, 2019 10:18 PM
> > To: Zhang, Qi Z <qi.z.zhang@intel.com>; Yigit, Ferruh
> > <ferruh.yigit@intel.com>; Stokes, Ian <ian.stokes@intel.com>;
> > dev@dpdk.org
> > Cc: stephen@networkplumber.org; Lu, Wenzhuo <wenzhuo.lu@intel.com>;
> > Xing, Beilei <beilei.xing@intel.com>
> > Subject: RE: [dpdk-dev] [PATCH v2 6/7] net/e1000: set min and max MTU
> > for igb devices
> >
> >
> > > >
> > > > Hi Qi,
> > > >
> > > > > >
> > > > > > On 3/22/2019 1:01 PM, Ian Stokes wrote:
> > > > > > > This commit sets the min and max supported MTU values for
> > > > > > > igb devices via the eth_igb_info_get() function. Min MTU
> > > > > > > supported is set to ETHER_MIN_MTU and max mtu is calculated
> > > > > > > as the max packet length supported minus the transport
> > > > > > > overhead. To aid in these calculations a new MACRO
> > > > > > > 'E1000_ETH_OVERHEAD' has been introduced to consolidate
> > > > > > > overhead calculation and avoid
> > duplication.
> > > > > > >
> > > > > > > Signed-off-by: Ian Stokes <ian.stokes@intel.com>
> > > > > > > ---
> > > > > > > drivers/net/e1000/e1000_ethdev.h | 6 ++++++
> > > > > > > drivers/net/e1000/igb_ethdev.c | 7 +++++--
> > > > > > > 2 files changed, 11 insertions(+), 2 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/net/e1000/e1000_ethdev.h
> > > > > > > b/drivers/net/e1000/e1000_ethdev.h
> > > > > > > index 94edff08e..3e74cd8fe 100644
> > > > > > > --- a/drivers/net/e1000/e1000_ethdev.h
> > > > > > > +++ b/drivers/net/e1000/e1000_ethdev.h
> > > > > > > @@ -89,6 +89,12 @@
> > > > > > > ETH_RSS_IPV6_UDP_EX)
> > > > > > >
> > > > > > > /*
> > > > > > > + * The overhead from MTU to max frame size.
> > > > > > > + * Considering VLAN so a tag needs to be counted.
> > > > > > > + */
> > > > > > > +#define E1000_ETH_OVERHEAD (ETHER_HDR_LEN + ETHER_CRC_LEN
> +
> > > > > > > +VLAN_TAG_SIZE)
> > > > > >
> > > > > > As an overhead, following drivers set:
> > > > > > i40e: HDR + CRC + 2 * VLAN
> > > > > > ixgbe: HDR + CRC
> > > > > > e1000: HDR + CRC + VLAN
> > > > > >
> > > > > > I wonder if this difference is HW limitation, or driver
> > > > > > limitation or just implementation inconsistency.
> > > > >
> > > > > I think this is implementation inconsistency
> > > > >
> > > > > The NIC only accept Max Frame Size.
Sorry , I need to correct above statement, by checking the ixgbe datasheet, actually max frame size is not include VLAN
Packet with VLAN can be as large as MFS +4 and packet with double vlan can be MFS + 8. It's different with i40e.
So current implementation for mtu overhead subtraction for i40e and ixgbe looks good for me.
> > > > >
> > > > > The problem here is seems all of three setup are not perfect.
> > > > >
> > > > > HDR + CRC + 2 * VLAN - it may allow non vlan or single vlan
> > > > > packet that exceed
> > > > mtu.
> > > >
> > > > Hmm, wonder how?
> > >
> > > I'm talking about the case:
> > >
> > > Assume mtu = 1500, we will set max frame size to 1500 + 14 + 4 +
> > > 2*4 = 1526 Let's assume a non vlan packet with 1522 size, so its l2
> > > payload will be 1504 that exceed the mtu, but it will still be
> > > accepted, does it
> > break the configure?
> >
> > Of course it would, but as I can read the mail, we discussing overhead
> > to subtract from max_rx_pkt_len to report max allowable mtu.
> > From that perspective bigger overhead is more conservative and makes
> > sure our tx packet will never be bigger than max_rx_pkt_len.
> > Konstantin
>
> I'm OK to choose HDR + CRC + 2 * VLAN as MTU overhead to keep all driver
> consistent.
>
> Qi
>
> >
> > >
> > > >
> > > > > HDR + CRC - it may reject vlan or double vlan packet that follow mtu.
> > > > > HDR + CRC + VLAN , it may reject double vlan packet that follow
> > > > > mtu
> > > > >
> > > > > I agree it's better to keep consistent on all drivers, but
> > > > > before this, we may need to decide which one we should take :)
> > > > >
> > > > > Regards
> > > > > Qi
> > > > >
> > > > > >
> > > > > > Better to confirm it that it is not implementation inconsistency.
> > > > > >
> > > > > > Wenzhuo, Konstantin, Beilei, Qi,
> > > > > >
> > > > > > Can you please comment?
> > > > > >
> > > > > > Thanks,
> > > > > > ferruh
next prev parent reply other threads:[~2019-03-27 7:02 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-22 13:01 [dpdk-dev] [PATCH v2 0/7] ethdev: add min/max MTU to device info Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 1/7] " Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-25 14:26 ` Ferruh Yigit
2019-03-25 14:26 ` Ferruh Yigit
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 2/7] net/i40e: set min and max MTU for i40e devices Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 3/7] net/i40e: set min and max MTU for i40e VF devices Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 4/7] net/ixgbe: set min and max MTU for ixgbe devices Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 5/7] net/ixgbe: set min and max MTU for ixgbe VF devices Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 6/7] net/e1000: set min and max MTU for igb devices Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-25 14:25 ` Ferruh Yigit
2019-03-25 14:25 ` Ferruh Yigit
2019-03-26 13:58 ` Zhang, Qi Z
2019-03-26 13:58 ` Zhang, Qi Z
2019-03-26 14:02 ` Ananyev, Konstantin
2019-03-26 14:02 ` Ananyev, Konstantin
2019-03-26 14:09 ` Zhang, Qi Z
2019-03-26 14:09 ` Zhang, Qi Z
2019-03-26 14:18 ` Ananyev, Konstantin
2019-03-26 14:18 ` Ananyev, Konstantin
2019-03-27 1:13 ` Zhang, Qi Z
2019-03-27 1:13 ` Zhang, Qi Z
2019-03-27 7:02 ` Zhang, Qi Z [this message]
2019-03-27 7:02 ` Zhang, Qi Z
2019-03-22 13:01 ` [dpdk-dev] [PATCH v2 7/7] app/testpmd: verify mtu with rte_eth_dev_info_get() Ian Stokes
2019-03-22 13:01 ` Ian Stokes
2019-03-25 14:20 ` Ferruh Yigit
2019-03-25 14:20 ` Ferruh Yigit
2019-03-28 16:41 ` Ferruh Yigit
2019-03-28 16:41 ` Ferruh Yigit
2019-03-28 16:43 ` [dpdk-dev] [PATCH v2 0/7] ethdev: add min/max MTU to device info Ferruh Yigit
2019-03-28 16:43 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 1/7] " Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 2/7] net/i40e: set min and max MTU for i40e devices Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 3/7] net/i40e: set min and max MTU for i40e VF devices Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 4/7] net/ixgbe: set min and max MTU for ixgbe devices Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 5/7] net/ixgbe: set min and max MTU for ixgbe VF devices Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 6/7] net/e1000: set min and max MTU for igb devices Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:52 ` [dpdk-dev] [PATCH v3 7/7] app/testpmd: verify MTU with device provided limits Ferruh Yigit
2019-03-29 17:52 ` Ferruh Yigit
2019-03-29 17:56 ` [dpdk-dev] [PATCH v3 1/7] ethdev: add min/max MTU to device info Ferruh Yigit
2019-03-29 17:56 ` Ferruh Yigit
2019-03-29 18:05 ` Ferruh Yigit
2019-03-29 18:05 ` Ferruh Yigit
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