Re: [PATCH 1/1] TX throttling bug-fixing patch of AX88179_178A

[Eric Dumazet]

On Mon, 2013-07-22 at 19:38 +0100, Ben Hutchings wrote:
> On Mon, 2013-07-22 at 11:29 -0700, Grant Grundler wrote:
> > On Mon, Jul 22, 2013 at 10:07 AM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> > ...
> > > I guess that if a driver does not advertise NETIF_F_SG, this
> > > skb_linearize() call is not needed : All frames reaching your xmit
> > > function should already be linear
> > 
> > As Ben Hutchings pointed out, hw_features is still setting this...but
> > I'm not sure how that matters.
> > 
> > ax88179_set_features() doesn't allow setting SG or TSO features.  But
> > I expect it would be "not too difficult" to add such that ethtool
> > could set those features after boot.
> [...]
> 
> It already can.  That's what putting feature flags in hw_features does.

My original concern, that inspired this patch, was to remove SG support,
as this driver does not have SG support at all.

Linearize a full TSO packet needs order-5 allocations, thats likely to
fail and lead to very slow TCP performance, because it will only rely on
retransmits.



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