Re: Difficulties to get 1Gbps on be2net ethernet card

2012/5/30  [off-list ref]:

quoted

-----Original Message-----
From: <redacted> [mailto:<redacted>] On
Behalf Of Jean-Michel Hautbois

2012/5/30 Jean-Michel Hautbois [off-list ref]:

I used vmstat in order to see the differences between the two kernels.
The main difference is the number of interrupts per second.
I have an average of 87500 on 3.2 and 7500 on 2.6, 10 times lower !
I suspect the be2net driver to be the main cause, and I checkes the
/proc/interrupts file in order to be sure.

I have for eth1-tx on 2.6.26 about 2200 interrupts per second and 23000 on 3.2.
BTW, it is named eth1-q0 on 3.2 (and tx and rx are the same IRQ)
whereas there is eth1-rx0 and eth1-tx on 2.6.26.

Yes, there is an issue with be2net interrupt mitigation in the recent code with
RX and TX on the same Evt-Q (commit 10ef9ab4). The high interrupt rate happens when a TX blast is
done while RX is relatively silent on a queue pair. Interrupt rate due to TX completions is not being
mitigated.

I have a fix and will send it out soon..

thanks,
-Sathya

It seems this issue exist with mellanox mlx4 too...
I have a bond between eth1 (be2net) and eth9 (mlx4_en) and I can
switch from one to the other using ifenslave.
Setting a queue of 4000 on be2net works well in my use case, when I
switch to mlx4 based NIC which has a default queue len of 1000, I have
dropped packets too (less than be2net, but about 30-50 per second).
Setting a queue len of 4000 on mlx4 works too, but the number of
interrupts is similar.
The use case is the same : Lots of TX, no RX.

JM