Message-ID: <1374765088.23313.21.camel@edumazet-glaptop>
Subject: Re: [PATCH 1/1] TX throttling bug-fixing patch of AX88179_178A
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Ming Lei <tom.leiming@gmail.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>,
        Oliver Neukum <oliver@neukum.org>,
        Grant Grundler <grundler@google.com>, Freddy Xin <freddy@asix.com.tw>,
        David Miller <davem@davemloft.net>, netdev <netdev@vger.kernel.org>,
        linux-usb@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        ASIX Louis =?UTF-8?Q?=5B=E8=98=87=E5=A8=81=E9=99=B8=5D?= 
	<louis@asix.com.tw>,
        Allan Chou <allan@asix.com.tw>
Date: Thu, 25 Jul 2013 08:11:28 -0700
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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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