[etherlab-users] Generic vs HW-specific NIC Drivers

Sebastien Blanchet blanchet at iram.fr
Thu Jan 7 12:21:23 CET 2016


Device specific drivers operate without interrupts, so they are expected to have 
a smaller jitter than generic driver. In practice there is no performance 
difference when the control loop runs below 1 KHz.


On 01/06/2016 11:26 PM, John Hubbard wrote:
> Hello all.
> I would like to know what kinds of performance changes I might expect to see if
> I switched from the generic NIC driver to a device specific driver (e1000e in my
> case).  With the generic NIC driver I am currently seeing ecrt_master_receive
> calls averaging about 10us and ecrt_master_send times that are a few micro
> seconds longer. I don't need exact numbers just a rough idea.  Would using the
> custom e1000e driver reduce times by an order of magnitude, 50%, 5%?
> I would also like to know how sensitive the times are to PDO size?  I've tried
> registering fewer PDOs (i.e. ecrt_domain_reg_pdo_entry_list) and the difference
> in transmit/receive times seems to be nearly unaffected.  In addition I tried
> reducing the number of devices attached to my EK-1100 coupler and that also had
> little to no change in run times.  Are those results as expected?
> Thanks
> --
> -john

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