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Subject: Re: [RFC PATCH 4/6] kernel: faster queue spinlock implementation
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@redhat.com>,
        "Paul E. McKenney" <paulmck@us.ibm.com>,
        David Howells <dhowells@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Eric Dumazet <edumazet@google.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Manfred Spraul <manfred@colorfullife.com>,
        linux-kernel@vger.kernel.org
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Date: Wed, 23 Jan 2013 16:18:14 -0800
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On Tue, 2013-01-22 at 15:13 -0800, Michel Lespinasse wrote:
>  {
> -	__q_spin_unlock(lock, node);
> -	preempt_enable_no_resched();
> -	local_bh_enable_ip((unsigned long)__builtin_return_address(0));
> +	unsigned int cpu, i;
> +	struct q_spinlock_token *token;
> +	for_each_possible_cpu(cpu)
> +		for (i = 0; i < 2; i++) {
> +			token = kmalloc(sizeof(struct q_spinlock_alloc_token),
> +					GFP_KERNEL);
> +			BUG_ON(!token);
> +			token->wait = false;
> +			per_cpu(q_spinlock_token[i], cpu) = token;
> +		}

You might use kmalloc_node(...   , cpu_to_node(cpu)) to spread these
tokens on all nodes.