netdev - Re: TCPBacklogDrops during aggressive bursts of traffic

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Date:	Tue, 15 May 2012 17:47:34 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Kieran Mansley <kmansley@...arflare.com>, <netdev@...r.kernel.org>
Subject: Re: TCPBacklogDrops during aggressive bursts of traffic

On Tue, 2012-05-15 at 18:34 +0200, Eric Dumazet wrote:
> On Tue, 2012-05-15 at 17:29 +0100, Kieran Mansley wrote:
> > On Tue, 2012-05-15 at 16:56 +0200, Eric Dumazet wrote:
> > > 
> > > Please try latest kernels, this is probably 'fixed'
> > 
> > I've just tried with 3.4.0-rc7 and the problem is still reproducible.
> > It's perhaps harder to reproduce than on 3.3.6 but still there.
> > 
> > > What network driver are you using ? 
> > 
> > The receiver is using the sfc driver that is included in the kernel
> > build, together with an SFC 9020 NIC. 
> > 
> > Kieran
> > 
> 
> MTU ?

1500

> What is typical skb->truesize of skb given to stack in RX path ?
>
> If drivers use PAGE_SIZE fragments, then you are more likely to hit
> limit.

We're passing page fragments into GRO.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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