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

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Message-ID: <1395064808.9668.42.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 17 Mar 2014 07:00:08 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Pablo Neira Ayuso <pablo@...filter.org>
Cc:	netfilter-devel@...r.kernel.org, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH 36/38] netfilter: connlimit: use keyed locks

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)

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 !

I believe this hash table of spinlocks could be global, not in each
struct xt_connlimit_data.



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