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

From: Eric Dumazet
Date: Thu Jul 25 2013 - 11:11:41 EST

On Thu, 2013-07-25 at 22:52 +0800, Ming Lei wrote:

> Maybe need to try it with TSO enabled, in my test on ax88179_178a NIC after
> applying your disabling TSO patch, tx throughput is less than 600Mbps, but rx
> is close to 900Mbps.

It looks like TCP stack could for this case allocate linear skbs
(GFP_KERNEL context), using order-3 pages, and not adding frags on them,
to avoid the skb_linearize() hazard (in GFP_ATOMIC)

In case of retransmits, skb are small (one MSS) so the skb_linearize()
should succeed most of the time.

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