netdev - Re: [net-next PATCH 2/3] net: fix enforcing of fragment queue hash list depth

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Date:	Wed, 24 Apr 2013 08:05:09 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesper Dangaard Brouer <brouer@...hat.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	netdev@...r.kernel.org
Subject: Re: [net-next PATCH 2/3] net: fix enforcing of fragment queue hash
 list depth

On Wed, 2013-04-24 at 15:35 +0200, Jesper Dangaard Brouer wrote:
> On Fri, 2013-04-19 at 07:49 -0700, Eric Dumazet wrote:

> > Thats pretty irrelevant, memory is limited by the total amount of memory
> > used by fragments, not by hash table size.
> >
> > Its called /proc/sys/net/ipv4/ipfrag_high_thresh
> 
> 
> I was talking about patch-03, where I do "direct hash cleaning", and
> have moved the mem limit "ipfrag_high_thresh" into the hash cleaning
> step.

I am fine to remove LRU, as maintaining a LRU is too expensive and this
LRU has little purpose.

Old frags are evicted anyway because they have a timer.

We have to keep a global limit, especially if we increase hash table
size, because even with perfect hashing and one frag per hash slot we
might consume too much ram.

We can rename it if you wish but currently this is ipfrag_high_thresh.


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