netdev - Re: TCP performance regression

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Date:	Mon, 11 Nov 2013 23:59:37 +0530
From:	Sujith Manoharan <sujith@...jith.org>
To:	Dave Taht <dave.taht@...il.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Felix Fietkau <nbd@...nwrt.org>,
	"netdev\@vger.kernel.org" <netdev@...r.kernel.org>
Subject: Re: TCP performance regression

Dave Taht wrote:
> Personally I don't have much of a problem if TSQ hurts single stream
> TCP throughput on wifi. I would vastly prefer aggregation to work
> better for multiple streams with vastly smaller buffers than it does.
> That would be a bigger win, overall.

ath9k doesn't hold very deep queues for aggregated traffic. A maximum
of 128 packets can be buffered for each Access Class queue and still
good throughput is obtained, even for 3x3 scenarios.

A loss of almost 50% throughput is seen in 1x1 setups and the penalty
becomes higher with more streams. I don't think such a big loss
in performance is acceptable to achieve low latency.

Sujith
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