Re: [Xenomai] rt_e1000e driver issues

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On 09/02/2015 04:00 PM, Stéphane ANCELOT wrote:
> On 01/09/2015 12:20, Gilles Chanteperdrix wrote:
>> On Mon, Aug 31, 2015 at 08:30:03PM +0200, Gilles Chanteperdrix wrote:
>>> On Mon, Aug 31, 2015 at 04:04:18PM +0200, Stéphane ANCELOT wrote:
>>>> Hi,
>>>>
>>>> I am checking timing issues of realtime rtnet frames in my 
>>>> application.
>>>> Timing to send a frame is  convenient.
>>>> but I have some issues with the time to receive the frames.
>>>>
>>>> Although the RxDelays are cleared, the frame is received almost 
>>>> 175us later
>>>> than it should in comparison with a rt8169 driver (v2.6 version) 
>>>> and the
>>>> same application.
>>>>
>>>> Any idea where to look at first ?
>>> modinfo rt_e1000e
>> Actually, the module parameters are the same as the Linux driver,
>> so, they are documented in Documentation/networking/e1000e.txt in
>> the Linux kernel sources, here for instance:
>> https://git.xenomai.org/ipipe.git/tree/Documentation/networking/e1000e.txt?id=v4.2-rc1 
>>
>> (beware that the driver versions are not the same, so, there may be
>> some differences, like default values, or even some options, but
>> modinfo will tell you that).
>>
>> Your problem is probably that you should disable interrupt
>> throttling passing InterruptThrottleRate=0.
>>
> Hi,
> I checked the timerdelays settings everything seems rigth by default.
> However,  I think the main differences I mesure are related to the 
> usage of EarlyReceive in r8169 driver. Thus spending less time in recv 
> func .
>
> I will soon check the same application using the igb driver

I have made some round trip time measurement with two e1000e boards, and 
I am pretty sure
with InterruptThrottleRate=0 *RxDelay=0 the delays are in the 10s of 
microseconds order (on a
gigabit link).

--
                                                 Gilles Chanteperdrix