[RFC] Multi queue support in ethernet/freescale/ucc_geth.c

[RFC] Multi queue support in ethernet/freescale/ucc_geth.c

[Paul Gortmaker]

Hi Li,

A while back DaveM mentioned that it would be good to
break out the ring allocations[1] in this driver.

I was looking at it, and in the process noticed this:

$ grep 'numQueues.*=' drivers/net/ethernet/freescale/ucc_geth.c 
        .numQueuesTx = 1,
        .numQueuesRx = 1,
$ 

My interpretation of the above is that there is no way
(aside from a code edit) to enable multi queue support.
They are only ever assigned one time, to a value of one.

Assuming I'm not missing something obvious, is the multi
queue support functional and tested, or just old code
that never got tested and subsequently enabled?

The reason I ask, is that the ring allocation code gets rid
of the loop wrapping it, if the driver is really only meant
to ever have just single queues for Rx/Tx. And other areas
of the driver can also be simplified accordingly as well.

Thanks,
Paul.

[1] http://lists.openwall.net/netdev/2010/09/06/45

RE: [RFC] Multi queue support in ethernet/freescale/ucc_geth.c

[Li Yang-R58472]

> -----Original Message-----
> From: Paul Gortmaker [mailto:paul.gortmaker@windriver.com]
> Sent: Friday, February 03, 2012 6:42 AM
> To: Li Yang-R58472
> Cc: netdev@vger.kernel.org; linuxppc-dev@lists.ozlabs.org
> Subject: [RFC] Multi queue support in ethernet/freescale/ucc_geth.c
>=20
> Hi Li,

Hi Paul,

Sorry for the late response due to holidays.

>=20
> A while back DaveM mentioned that it would be good to break out the ring
> allocations[1] in this driver.
>=20
> I was looking at it, and in the process noticed this:
>=20
> $ grep 'numQueues.*=3D' drivers/net/ethernet/freescale/ucc_geth.c
>         .numQueuesTx =3D 1,
>         .numQueuesRx =3D 1,
> $
>=20
> My interpretation of the above is that there is no way (aside from a code
> edit) to enable multi queue support.
> They are only ever assigned one time, to a value of one.
>=20
> Assuming I'm not missing something obvious, is the multi queue support
> functional and tested, or just old code that never got tested and
> subsequently enabled?

Previously the device is only used on single core cpu, so we didn't have th=
e incentive to enable multi-queue.  It is not tested on Linux currently.

>=20
> The reason I ask, is that the ring allocation code gets rid of the loop
> wrapping it, if the driver is really only meant to ever have just single
> queues for Rx/Tx. And other areas of the driver can also be simplified
> accordingly as well.

Well.  I would prefer the other way which is to add the multi-queue support=
 as we are using the QE in multi-core SoC and the current driver is having =
almost all the code needed for multi-queue except interface to the protocol=
 layer.

- Leo