netdev - Re: [Question] net/mlx4_en: Memory consumption issue with mlx4

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Message-ID: <20150312165647.GD1032293@devbig242.prn2.facebook.com>
Date:	Thu, 12 Mar 2015 09:56:47 -0700
From:	Martin Lau <kafai@...com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Amir Vadai <amirv@...lanox.com>,
	Or Gerlitz <ogerlitz@...lanox.com>, <netdev@...r.kernel.org>,
	<kernel-team@...com>
Subject: Re: [Question] net/mlx4_en: Memory consumption issue with mlx4_en
 driver

On Wed, Mar 11, 2015 at 01:21:02PM -0700, Eric Dumazet wrote:
> You know, even the order-3 allocations done for regular skb allocations
> will hurt you : a single copybreaked skb stored a long time in a tcp
> receive queue will hold 32KB of memory.
> 
> Even 4KB can lead to disasters.
Thanks for the pointer.  I look a little deeper at the allocation in skbuff.c.
I can see your point.

> You could lower tcp_rmem so that collapsing happens sooner.
It is what we did.  However, a buggy process accommodated enough stalled
sockets (stop reading from it but not closing it) will re-surface the problem.

Thanks,
--Martin
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