From mboxrd@z Thu Jan  1 00:00:00 1970
From: Florian Westphal <fw@strlen.de>
Subject: Re: [net-next PATCH V3-evictor] net: frag evictor, avoid killing
 warm frag queues
Date: Thu, 6 Dec 2012 13:32:48 +0100
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Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org,
	Thomas Graf <tgraf@suug.ch>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Cong Wang <amwang@redhat.com>,
	Herbert Xu <herbert@gondor.hengli.com.au>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
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Jesper Dangaard Brouer <jbrouer@redhat.com> wrote:
> CPUs are fighting for the same LRU head (inet_frag_queue) element,
> which is bad for scalability.  We could fix this by unlinking the
> element once a CPU graps it, but it would require us to change a
> read_lock to a write_lock, thus we might not gain much performance.
> 
> I already (implicit) fix this is a later patch, where I'm moving the
> LRU lists to be per CPU.  So, I don't know if it's worth fixing.

Do you think its worth trying to remove the lru list altogether and
just evict from the hash in a round-robin fashion instead?