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From: Olivier MATZ <olivier.matz@6wind.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [RFC 00/16] enhance checksum offload API
Date: Fri, 23 Jan 2015 10:52:06 +0100	[thread overview]
Message-ID: <54C219C6.8080304@6wind.com> (raw)
In-Reply-To: <20150121170149.157da6ed@urahara>

Hi Stephen,

On 01/22/2015 02:01 AM, Stephen Hemminger wrote:
> On Thu, 22 Jan 2015 00:36:19 +0100
> Olivier Matz <olivier.matz@6wind.com> wrote:
> 
>> The goal of this series is to clarify and simplify the mbuf offload API.
>> Several issues are solved:
> 
> If you are doing this could you invert the meaning of the checksum
> flags? Right now the flags are fine for Intel hardware but are useless
> for devices that have less checksum support.
> 
> It would work better if instead of two states:
>   * Checksum known bad    =>  PKT_RX_L4_CKSUM_BAD == 1
>   * Checksum (maybe) good =>  PKT_RX_L4_CKSUM_BAD == 0
> The bit was changed to only flag good checksum:
>   * Checksum known good	    => PKT_RX_L4_CKSUM_GOOD == 1
>   * Checksum status unknown => PKT_RX_L4_CKSUM_GOOD == 0
> 
> That way code code fallback to software checksum if hardware was incapable
> of handling the packet. It does mean packets with bad checksums get checked
> twice, but thats ok.

I agree that current rx checksum flags in dpdk could be enhanced.
Your proposition is indeed already much better that what we currently
have. I'm ok to submit a patch for this before the 2.0 release.

However, I think we could do even better with 2 flags. The first
idea is to have one bit saying "the hw verified the checksum" and
a second one saying "it is good or bad".

The second idea is to use flags like PKT_RX_L4_TCP or PKT_RX_L4_UDP
to replace the first bit of the first idea, like it's done for IPv4.
Therefore, the value of the flag PKT_RX_L4_CKSUM_GOOD should only
be checked if the L4 protocol is recognized.

Another thing that could be also useful for virtual driver is a
way to say: "the packet integrity is correct but the checksum field
in the packet may be wrong". This can happen for instance in this
case:
- a guest transmits on a vdev without calculating the checksums
  (gaining cpu time)
- the host receives it, it does not check the rx checksums (because
  it knows the packet integrity is correct, the packet comes from
  memory not from a network)
- then if the host wants to forward it, it has to schedule a tx
  checksum on a real hw.

Let me know if you have any comment.

However, I think this will conflicts with the packet_type feature that
is proposed by Helin:
http://dpdk.org/ml/archives/dev/2015-January/011156.html


Regards,
Olivier

  reply	other threads:[~2015-01-23  9:52 UTC|newest]

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-21 23:36 Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 01/16] mbuf: remove PKT_TX_IPV4_CSUM Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 02/16] mbuf: enhance the API documentation of offload flags Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 03/16] i40e: call i40e_txd_enable_checksum only for offloaded packets Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 04/16] i40e: remove the use of PKT_TX_UDP_TUNNEL_PKT flag Olivier Matz
2015-01-23  8:06   ` Liu, Jijiang
2015-01-23  8:47     ` Zhang, Helin
2015-01-23  9:06       ` Olivier MATZ
2015-01-21 23:36 ` [dpdk-dev] [RFC 05/16] mbuf: remove " Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 06/16] ethdev: add outer IP offload capability flag Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 07/16] i40e: advertise outer IPv4 checksum capability Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 08/16] testpmd: replace tx_checksum command by csum Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 09/16] testpmd: move csum_show in a function Olivier Matz
2015-01-23 11:03   ` Liu, Jijiang
2015-01-23 17:53     ` Olivier MATZ
2015-01-21 23:36 ` [dpdk-dev] [RFC 10/16] testpmd: add csum parse_tunnel command Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 11/16] testpmd: rename vxlan in outer_ip in csum commands Olivier Matz
2015-01-23 11:21   ` Liu, Jijiang
2015-01-23 17:49     ` Olivier MATZ
2015-01-21 23:36 ` [dpdk-dev] [RFC 12/16] testpmd: introduce parse_ipv* in csum fwd engine Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 13/16] testpmd: use a structure to store offload info " Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 14/16] testpmd: introduce parse_vxlan " Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 15/16] testpmd: support gre tunnels " Olivier Matz
2015-01-21 23:36 ` [dpdk-dev] [RFC 16/16] testpmd: support ipip tunnel in csum forward engine Olivier Matz
2015-01-21 23:41 ` [dpdk-dev] [RFC 00/16] enhance checksum offload API Olivier MATZ
2015-01-22 10:00   ` Thomas Monjalon
2015-01-22  1:01 ` Stephen Hemminger
2015-01-23  9:52   ` Olivier MATZ [this message]
2015-01-23  7:54 ` Liu, Jijiang
2015-01-30 13:15 ` [dpdk-dev] [PATCH 00/20] enhance tx " Olivier Matz
2015-01-30 13:15   ` [dpdk-dev] [PATCH 01/20] mbuf: remove PKT_TX_IPV4_CSUM Olivier Matz
2015-01-30 13:15   ` [dpdk-dev] [PATCH 02/20] mbuf: enhance the API documentation of offload flags Olivier Matz
2015-01-30 13:15   ` [dpdk-dev] [PATCH 03/20] i40e: call i40e_txd_enable_checksum only for offloaded packets Olivier Matz
2015-01-30 13:15   ` [dpdk-dev] [PATCH 04/20] i40e: remove the use of PKT_TX_UDP_TUNNEL_PKT flag Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 05/20] mbuf: remove " Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 06/20] testpmd: replace tx_checksum command by csum Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 07/20] testpmd: move csum_show in a function Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 08/20] testpmd: add csum parse_tunnel command Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 09/20] testpmd: rename vxlan in outer_ip in csum commands Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 10/20] testpmd: introduce parse_ipv* in csum fwd engine Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 11/20] testpmd: use a structure to store offload info " Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 12/20] testpmd: introduce parse_vxlan " Olivier Matz
2015-02-02  1:49     ` Liu, Jijiang
2015-01-30 13:16   ` [dpdk-dev] [PATCH 13/20] testpmd: support gre tunnels " Olivier Matz
2015-02-02  3:04     ` Liu, Jijiang
2015-01-30 13:16   ` [dpdk-dev] [PATCH 14/20] testpmd: support ipip tunnel in csum forward engine Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 15/20] ethdev: add outer IP offload capability flag Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 16/20] i40e: advertise outer IPv4 checksum capability Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 17/20] testpmd: add a warning if outer ip cksum requested but not supported Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 18/20] testpmd: fix TSO when using outer checksum offloads Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 19/20] i40e: fix offloading of outer checksum for ip in ip tunnels Olivier Matz
2015-01-30 13:16   ` [dpdk-dev] [PATCH 20/20] i40e: add debug logs for tx context descriptors Olivier Matz
2015-02-04  9:25   ` [dpdk-dev] [PATCH v2 00/20] enhance tx checksum offload API Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 01/20] mbuf: remove PKT_TX_IPV4_CSUM Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 02/20] mbuf: enhance the API documentation of offload flags Olivier Matz
2015-02-10  5:38       ` Zhang, Helin
2015-02-10 16:54         ` Olivier MATZ
2015-02-11  7:15         ` Liu, Jijiang
2015-02-11 15:15           ` Olivier MATZ
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 03/20] i40e: call i40e_txd_enable_checksum only for offloaded packets Olivier Matz
2015-02-10  6:03       ` Zhang, Helin
2015-02-10 17:06         ` Olivier MATZ
2015-02-11  5:32           ` Zhang, Helin
2015-02-11 17:13             ` Olivier MATZ
2015-02-13  2:25               ` Zhang, Helin
2015-02-13  8:41                 ` Olivier MATZ
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 04/20] i40e: remove the use of PKT_TX_UDP_TUNNEL_PKT flag Olivier Matz
2015-02-10  6:40       ` Zhang, Helin
2015-02-10 17:08         ` Olivier MATZ
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 05/20] mbuf: remove " Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 06/20] testpmd: replace tx_checksum command by csum Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 07/20] testpmd: move csum_show in a function Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 08/20] testpmd: add csum parse_tunnel command Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 09/20] testpmd: rename vxlan in outer_ip in csum commands Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 10/20] testpmd: introduce parse_ipv* in csum fwd engine Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 11/20] testpmd: use a structure to store offload info " Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 12/20] testpmd: introduce parse_vxlan " Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 13/20] testpmd: support gre tunnels " Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 14/20] testpmd: support ipip tunnel in csum forward engine Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 15/20] ethdev: add outer IP offload capability flag Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 16/20] i40e: advertise outer IPv4 checksum capability Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 17/20] testpmd: add a warning if outer ip cksum requested but not supported Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 18/20] testpmd: fix TSO when using outer checksum offloads Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 19/20] i40e: fix offloading of outer checksum for ip in ip tunnels Olivier Matz
2015-02-04  9:25     ` [dpdk-dev] [PATCH v2 20/20] i40e: add debug logs for tx context descriptors Olivier Matz
2015-02-09  1:10     ` [dpdk-dev] [PATCH v2 00/20] enhance tx checksum offload API Liu, Jijiang
2015-02-13  9:22     ` [dpdk-dev] [PATCH v3 " Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 01/20] mbuf: remove PKT_TX_IPV4_CSUM Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 02/20] mbuf: enhance the API documentation of offload flags Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 03/20] i40e: call i40e_txd_enable_checksum only for offloaded packets Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 04/20] i40e: remove the use of PKT_TX_UDP_TUNNEL_PKT flag Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 05/20] mbuf: remove " Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 06/20] testpmd: replace tx_checksum command by csum Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 07/20] testpmd: move csum_show in a function Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 08/20] testpmd: add csum parse_tunnel command Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 09/20] testpmd: rename vxlan in outer_ip in csum commands Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 10/20] testpmd: introduce parse_ipv* in csum fwd engine Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 11/20] testpmd: use a structure to store offload info " Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 12/20] testpmd: introduce parse_vxlan " Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 13/20] testpmd: support gre tunnels " Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 14/20] testpmd: support ipip tunnel in csum forward engine Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 15/20] ethdev: add outer IP offload capability flag Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 16/20] i40e: advertise outer IPv4 checksum capability Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 17/20] testpmd: add a warning if outer ip cksum requested but not supported Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 18/20] testpmd: fix TSO when using outer checksum offloads Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 19/20] i40e: fix offloading of outer checksum for ip in ip tunnels Olivier Matz
2015-02-13  9:22       ` [dpdk-dev] [PATCH v3 20/20] i40e: add debug logs for tx context descriptors Olivier Matz
2015-02-15  6:22       ` [dpdk-dev] [PATCH v3 00/20] enhance tx checksum offload API Liu, Jijiang
2015-02-16 18:23         ` Thomas Monjalon

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