Paul Durrant wrote:
> On 18/09/2007, Matty <matty91 at gmail.com> wrote:
>
>> What exactly is soft-lso? Is there a PSARC case that describes this feature?
>>
>>
>
> One assumes this is a modification to the GLDv3 mac module to disect
> an LSO packet into MTU size packets such that the driver/hardware can
> be LSO-unaware whilst still giving some proportion of the LSO benefit
> by allowing large packets to pass down the stack from TCP?
>
> One question would be how the benefit of doing a single DMA-map for
> the LSO payload could be done if the packet is already segmented.
>
> Paul
>
>
One might imagine that soft LSO works differently. Imagine soft-lso as
a subroutine, which, given a large TCP segment, and the MTU size, builds
a series of header mblks, and maps the data segment in one operation
(perhaps making use of multiple DMA cookies, etc. to deal with page
boundaries, etc.) giving the appearance of LSO to the upper layers,
while allowing a NIC that only has the simple ability to use more than 1
descriptor per ethernet frame to use a single DMA setup operation.
This is just conjectural on my part... I've not looked at Roamer's
actual implementation....
-- Garrett
