netdev - Make TCP work better with re-ordered frames?

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Message-ID: <573C758E.9050008@candelatech.com>
Date:	Wed, 18 May 2016 07:00:46 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Make TCP work better with re-ordered frames?

We are investigating a system that has fairly poor TCP throughput
with the 3.17 and 4.0 kernels, but evidently it worked pretty well
with 3.14 (I should be able to verify 3.14 later today).

One thing I notice is that a UDP download test shows lots of reordered
frames, so I am thinking maybe TCP is running slow because of this.

(We see about 800Mbps UDP download, but only 500Mbps TCP, even when
  using 100 concurrent TCP streams.)

Is there some way to tune the TCP stack to better handle reordered frames?

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com