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Date: Tue, 21 Apr 2009 07:23:31 +1000
From: Paul Mackerras <paulus@samba.org>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>, paulmck@linux.vnet.ibm.com,
       Evgeniy Polyakov <zbr@ioremap.net>, David Miller <davem@davemloft.net>,
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       netfilter-devel@vger.kernel.org, netdev@vger.kernel.org,
       benh@kernel.crashing.org, mathieu.desnoyers@polymtl.ca
Subject: Re: [PATCH] netfilter: use per-cpu recursive lock (v10)
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Eric Dumazet writes:

> OK, but we still have a problem on machines with >= 250 cpus,
> because calling 250 times spin_lock() is going to overflow preempt_count,
> as each spin_lock() increases preempt_count by one.

Huh?  Each cpu has its own separate preempt_count.

Paul.