Re: iwlwifi and tx info in skb->cb

[Johannes Berg <johannes@sipsolutions.net>]

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> >  > Currently we actively use 2 of them. First for TX command second for
> >  > actual frame.  It would be even worth if we need to expand
> >  > each packet also for TX command.
> >
> >  We will no longer do that after davem and I figure out those allocation
> >  patches.
> 
> Not sure these things are connected. TX command is allocated fixed for each TFD.

Ah, no, I misread that. Well, I think it might still help to say you
need N bytes headroom and use those since you wouldn't have to allocate
an extra skb.

> >  You should implement TCP checksumming in the hardware. *that* would help
> >  a lot.
> 
> There is already pretty much deal of link layer in software to reduce
> the cost and the complexity of the HW for these softmac NICs so
> this would be kind of strange investment...but I didn't invest much
> thoughts into yet.
> There are probably other means to utilize scatter gather DMA then TCP
> off loading. Are they any other source of scattered packets maybe
> iovec?

Well as far as I know those too would be zero-copy IO which only works
if you have TCP checksumming in hardware.

johannes

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