linux-kernel - Re: [PATCH] netfilter: use per-cpu recursive lock (v10)

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Message-ID: <18924.59347.375292.102385@cargo.ozlabs.ibm.com>
Date:	Tue, 21 Apr 2009 07:23:31 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Eric Dumazet <dada1@...mosbay.com>
Cc:	Stephen Hemminger <shemminger@...tta.com>,
	paulmck@...ux.vnet.ibm.com, Evgeniy Polyakov <zbr@...emap.net>,
	David Miller <davem@...emloft.net>, kaber@...sh.net,
	torvalds@...ux-foundation.org, jeff.chua.linux@...il.com,
	mingo@...e.hu, laijs@...fujitsu.com, jengelh@...ozas.de,
	r000n@...0n.net, linux-kernel@...r.kernel.org,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	benh@...nel.crashing.org, mathieu.desnoyers@...ymtl.ca
Subject: Re: [PATCH] netfilter: use per-cpu recursive lock (v10)

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.
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