netdev - Re: [PATCH 36/38] netfilter: connlimit: use keyed locks

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Date:	Tue, 18 Mar 2014 14:46:16 +0100
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	brouer@...hat.com, Pablo Neira Ayuso <pablo@...filter.org>,
	netfilter-devel@...r.kernel.org, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH 36/38] netfilter: connlimit: use keyed locks

On Mon, 17 Mar 2014 07:00:08 -0700
Eric Dumazet <eric.dumazet@...il.com> wrote:

> On Mon, 2014-03-17 at 13:42 +0100, Pablo Neira Ayuso wrote:
> > From: Florian Westphal <fw@...len.de>
> > 
> > connlimit currently suffers from spinlock contention, example for
> > 4-core system with rps enabled:
> 
> > +#define CONNLIMIT_SLOTS	256
> > +#define CONNLIMIT_LOCK_SLOTS	32
> 
> 
> 
> 32 spinlocks use 2 cache lines (assuming 4 bytes per spinlock, and 64
> bytes cache lines)

Hehe, I actually also pointed this out during my internal review, but
we never gotten around to fixing this.

> So I guess this probably should be increased to have less false sharing.
> 
> Note: This can be done later, I do not want to block this patch serie at
> all !

Yes, lets fix it up later.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer
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