ixgbe tcp cksum offload

ixgbe tcp cksum offload

[Tim Deng]

Hi,


I am trying to use ixgbe tcp cksum h/w offload by following steps:
- populate pseudo cksum
- set l2_len, l3_len, l4_len
- set ol_flags


But I found the pkt doesn't get right h/w checksum by sniffing on recv side, and TCP cksum still leave with the original pseudo cksum. 
And I verified those meta are correctly set, e.g. a TCP syn pkt:
l2_len = 14, l3_len = 20, l4_len = 40 (with some tcp options),
and ol_flags = 0x90000000000000 which means PKT_TX_IPV4 | PKT_TX_TCP_CKSUM


Did I miss any step?


Thanks in advance,
Tim

Re: ixgbe tcp cksum offload

[Bruce Richardson]

On Mon, May 25, 2015 at 06:15:23PM +0800, Tim Deng wrote:
> Hi,
> 
> 
> I am trying to use ixgbe tcp cksum h/w offload by following steps:
> - populate pseudo cksum
> - set l2_len, l3_len, l4_len
> - set ol_flags
> 
> 
> But I found the pkt doesn't get right h/w checksum by sniffing on recv side, and TCP cksum still leave with the original pseudo cksum. 
> And I verified those meta are correctly set, e.g. a TCP syn pkt:
> l2_len = 14, l3_len = 20, l4_len = 40 (with some tcp options),
> and ol_flags = 0x90000000000000 which means PKT_TX_IPV4 | PKT_TX_TCP_CKSUM
> 
> 
> Did I miss any step?
> 
> 
> Thanks in advance,
> Tim
> 
Check that you have not got TX offloads disabled in your port configuration. If
you pass in NULL for the rte_eth_txconf pointer on tx queue setup, then offloads
will be disabled. To get offloads such as checksums to work, you need to explicitly
set the flags to allow them. (Generally, this means just setting txqflags to 0)

Regards,
/Bruce

Re: ixgbe tcp cksum offload

[Tim Deng]

Thanks Bruce so much! That perfectly solves my problem.
Tim


At 2015-05-25 18:28:48, "Bruce Richardson" <bruce.richardson@intel.com> wrote:
>On Mon, May 25, 2015 at 06:15:23PM +0800, Tim Deng wrote:
>> Hi,
>> 
>> 
>> I am trying to use ixgbe tcp cksum h/w offload by following steps:
>> - populate pseudo cksum
>> - set l2_len, l3_len, l4_len
>> - set ol_flags
>> 
>> 
>> But I found the pkt doesn't get right h/w checksum by sniffing on recv side, and TCP cksum still leave with the original pseudo cksum. 
>> And I verified those meta are correctly set, e.g. a TCP syn pkt:
>> l2_len = 14, l3_len = 20, l4_len = 40 (with some tcp options),
>> and ol_flags = 0x90000000000000 which means PKT_TX_IPV4 | PKT_TX_TCP_CKSUM
>> 
>> 
>> Did I miss any step?
>> 
>> 
>> Thanks in advance,
>> Tim
>> 
>Check that you have not got TX offloads disabled in your port configuration. If
>you pass in NULL for the rte_eth_txconf pointer on tx queue setup, then offloads
>will be disabled. To get offloads such as checksums to work, you need to explicitly
>set the flags to allow them. (Generally, this means just setting txqflags to 0)
>
>Regards,
>/Bruce
>