Re: [PATCH net-next 1/3] ibmvnic: Enable scatter-gather support

[Thomas Falcon <tlfalcon@linux.vnet.ibm.com>]

On 10/18/2017 06:04 AM, David Laight wrote:
> From: Thomas Falcon
>> Sent: 17 October 2017 18:37
>> This patch enables scatter gather support. Since there is no
>> HW/FW scatter-gather support at this time, the driver needs to
>> loop through each fragment and copy it to a contiguous, pre-mapped
>> buffer entry.
> ...
>>  	offset = index * adapter->req_mtu;
>>  	dst = tx_pool->long_term_buff.buff + offset;
> You should be able to treat the pre-allocated data area as a
> big ring buffer.
> So it can hold a lot of small frames or a few big ones.
> This slightly complicates the 'is there enough space for
> this packet' check since you need buffer space as well
> as a ring entry.
>
> You also really want to align each tx buffer on a 4n+2
> boundary so that most of the copy is aligned.

Thanks for your comments. I'll try to address that in a future patch.

>
>>  	memset(dst, 0, adapter->req_mtu);
> Seems unnecessary.

I removed that bit, and so far you seem to be right :) .

Thanks,
Tom
>
> 	David
>