[dpdk-dev] [PATCH v3 0/3] enhance TX checksum command and csum forwarding engine

[Liu, Jijiang]

Hi,

> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Monday, January 26, 2015 12:14 PM
> To: Olivier MATZ; Liu, Jijiang
> Cc: dev at dpdk.org
> Subject: RE: [dpdk-dev] [PATCH v3 0/3] enhance TX checksum command and
> csum forwarding engine
> 
> Hi lads,
> 
> > -----Original Message-----
> > From: Olivier MATZ [mailto:olivier.matz at 6wind.com]
> > Sent: Wednesday, January 21, 2015 3:25 PM
> > To: Liu, Jijiang; Ananyev, Konstantin
> > Cc: dev at dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v3 0/3] enhance TX checksum command and
> > csum forwarding engine
> >
> > Hi,
> >
> > On 01/21/2015 04:12 AM, Liu, Jijiang wrote:
> > >>>>> Ok, and why it should be our problem?
> > >>>>> We have a lot of things done in a different manner then
> > >>>>> linux/freebsd kernel drivers, Why now it became a problem?
> > >>>>
> > >>>> If linux doesn't need an equivalent flag for doing the same
> > >>>> thing, it probably means we don't need it either.
> > >>>
> > >>> Probably yes .... Or probably not.
> > >>> Why do we need to guess what was the intention of guys who wrote
> > >>> that
> > >> part of linux driver?
> > >>
> > >> Because the dpdk looks very similar to that part of linux driver.
> > >
> > > A  guy from Intel  who have already confirmed that the NVGRE is not
> supported yet in Linux kernel.
> > >
> > > He said "So far as I know it is not yet supported and I have no information on
> when it will be."
> >
> > I added the support of Ether over GRE, IP over GRE and IP over IP
> > tunnels in csumonly to do the test. I ask the csum forward engine to
> > calculate inner IP+TCP checksums, and outer IP (case 6 in [1]).
> > Here are the results:
> >
> > 1/ When I use I40E_TXD_CTX_UDP_TUNNELING:
> > - vxlan: all checksums ok
> > - eth over gre: all checksums ok
> > - ip over gre: not transmitted by hw
> > - ip over ip: all checksums wrong (set to 0 by hw)
> >
> > 2/ When I use I40E_TXD_CTX_GRE_TUNNELING:
> > - vxlan: checksums ok
> > - eth over gre: all checksums ok
> > - ip over gre: all checksums ok
> > - ip over ip: all checksums wrong (set to 0 by hw)
> >
> > 3/ When I use 00b:
> > - vxlan: all checksums ok
> > - eth over gre: all checksums ok
> > - ip over gre: all checksums ok
> > - ip over ip: checksums wrong (set to 0 by hw)
> >
> > All the ip over ip tests do not work yet for an unknown reason.
> > There is maybe something wrong in my app or in the driver (although
> > the registers looks consistent with the datasheet).
> >
> > I think we could use 3/ for all tunnels, because the ipip case is
> > supposed to work according to the datasheet, and all other cases work
> > too.
> >
> > It would allow to remove the UDP_TUNNELING flag from mbuf API.
> >
> > I will send a RFC patch that provides the API change and this new
> > feature in csum forward engine, with full tests on ixgbe and i40e and
> > explanations for all changes.
> >
> > Regards,
> > Olivier
> >
> > [1] http://dpdk.org/ml/archives/dev/2015-January/011127.html
> 
> I tried to repeat Olivier test-cases on my box.
> Though, I didn't use test-pmd cusmonly and  i40ePMD logic, but filled TCD and
> TDD mostly from hardcoded values.
> That's  what I got:
> 
> 4 input packets:
> a) ETHER/IPv4/UDP/VXLAN/ETHER/IPV4/TCP
> b) ETHER/IPv4/GRE/ETHER/IPV4/TCP
> c) ETHER/IPv4/GRE/IPV4/TCP
> d) ETHER/IPv4/IPV4/TCP
> 
> 1/ L4TUNT==1(I40E_TXD_CTX_UDP_TUNNELING):
> a),b): all checksums ok
> c),d): not transmitted by HW.
> 
> 2/ L4TUNT==2(I40E_TXD_CTX_GRE_TUNNELING):
> a) b),c): all checksums ok
> d): not transmitted by HW.
> 
> 3/ L4TUNT==0(UNKNOWN):
> a),b),c),d): all checksums ok
> 
> So yes, it seems that L4TUNT==0 works perfectly ok for all cases, as long as
> L4TUNLEN and other TCD values are setup properly.
> Which makes me think, that  probably we can do what you suggested: just use
> L4TUNT=0 for all cases.
> Though as Jijiang said, we waiting for confirmation from FVL guys, that there are
> no hidden implications with that approach.

Yes, the L4TUNT=0 is ok  for all cases.

But we still need to get confirmation from FVL guys, probably there are some issues in HW/FW.
I and Helin will confirm this with FVL guys ASAP.


> Another thing - IPIP seems to work ok by HW.
> There is something wrong on our (PMD/test-pmd) side.
> I think at least we have to remove the following check:
> if (!l2_len) {
>                 PMD_DRV_LOG(DEBUG, "L2 length set to 0");
>                 return;
>         }
> in i40e_txd_enable_checksum().

Yes, for IPIP, the check should be removed.

> Konstantin