Re: About Data Aggregation with RNDIS and u_ether Driver

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On Mon, May 21, 2012 at 07:18:37PM +0530, Mayank Rana wrote:
> Hi ,
> I am trying to understand possible way of implementing Data
> Aggregation with RNDIS and u_ether network interface driver to
> improve the throughput.
> Initial analysis seems that Network Interface is more faster than
> USB is able to transfer data with RNDIS USB Function.

So the USB bus is totally full, yet the network is empty at times?  Or
are there gaps on the USB traffic also?

> Possible Approaches:
> 1. Increasing the qmult ( Queue length multiplier at high speed )
> which would allow not to call netif_stop_queue frequently than less
> number of USB Requests. But still netif_stop_queue would call once
> limited number of USB requests are exhausted.
> 2. Using Multi packet approach at RNDIS protocol level ( combining
> multiple, 2 or more SKBs into one SKB ) of RNDIS Packet ( RNDIS
> Header + Received Ethernet Data ). Issue could be overhead involved
> here to create one SKB packet out of multiple SKBs with added RNDIS
> Header for each of the packet.
> 3. Is there any other possible approach to fine this network
> interface and USB RNDIS Function ?

Are you using multiple urbs to keep the pipe full to the USB device?
That's a requirement if you want to get proper throughput.


greg k-h
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