netdev - Re: Poor UDP throughput with virtual devices and UFO

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Message-ID: <1414424388.16231.13.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 27 Oct 2014 08:39:48 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
Cc:	netdev@...r.kernel.org, Herbert Xu <herbert@...dor.apana.org.au>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: Poor UDP throughput with virtual devices and UFO

On Mon, 2014-10-27 at 08:01 -0700, Eric Dumazet wrote:

> Please rewrite your patch to move the code out of tcp_gso_segment() into
> skb_segment()
> 
> Look how I carefully avoided many atomic operations on
> sk->sk_wmem_alloc, but how you removed it. :(
> 
> Alternative would be to use a single skb_set_owner_w() on the last
> segment, and tweak its truesize to not corrupt sk->sk_wmem_alloc
> 
> d6a4a1041176 was needed for people using GSO=off TSO=off on a bonding
> device, while best performance is reached with TSO=on so that
> segmentation is performed later on the slave device.

Hmm.. I meant 6ff50cd55545d92 ("tcp: gso: do not generate out of order
packets")

I think I will test an alternative patch and send it, keeping you as the
author if you do not mind.

Thanks.


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