ix(intel) vs mlxen(mellanox) 10Gb performance

[Daniel Braniss]

sorry, it’s been a tough day, we had a major meltdown, caused by a faulty gbic :-(
anyways, could you tell me what to do?
comment out, fix the off by one?

the machine is not yet production.

thanks,
	danny

> On 18 Aug 2015, at 16:32, Hans Petter Selasky <hps at selasky.org> wrote:
> 
> On 08/18/15 14:53, Rick Macklem wrote:
>> 2572 	  	         ifp->if_hw_tsomax = 65518;
>>> >2573 	  	         ifp->if_hw_tsomaxsegcount = IXGBE_82599_SCATTER;
>>> >2574 	  	         ifp->if_hw_tsomaxsegsize = 2048;
> 
> Hi,
> 
> If IXGBE_82599_SCATTER is the maximum scatter/gather entries the hardware can do, remember to subtract one fragment for the TCP/IP-header mbuf!
> 
> I think there is an off-by-one here:
> 
> ifp->if_hw_tsomax = 65518;
> ifp->if_hw_tsomaxsegcount = IXGBE_82599_SCATTER - 1;
> ifp->if_hw_tsomaxsegsize = 2048;
> 
> Refer to:
> 
>>         *
>>         * NOTE: The TSO limits only apply to the data payload part of
>>         * a TCP/IP packet. That means there is no need to subtract
>>         * space for ethernet-, vlan-, IP- or TCP- headers from the
>>         * TSO limits unless the hardware driver in question requires
>>         * so.
> 
> In sys/net/if_var.h
> 
> Thank you!
> 
> --HPS
>