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Date: Wed, 5 Jul 2006 10:10:51 +1000
From: Paul Mackerras <paulus@samba.org>
To: Andrew Morton <akpm@osdl.org>
Cc: Keith Owens <kaos@sgi.com>, jes@sgi.com, torvalds@osdl.org,
       viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org
Subject: Re: [patch] reduce IPI noise due to /dev/cdrom open/close
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Andrew Morton writes:

> But I think it'd be better to do just a single raw_smp_processor_id() for
> this entire function:
> 
>   static void bh_lru_install(struct buffer_head *bh)
>   {
> 	struct buffer_head *evictee = NULL;
> 	struct bh_lru *lru;
> +	int cpu;
> 
> 	check_irqs_on();
> 	bh_lru_lock();
> +	cpu = raw_smp_processor_id();
> -	lru = &__get_cpu_var(bh_lrus);
> +	lru = per_cpu(bh_lrus, cpu);

Better still, use the __raw_get_cpu_var() that I introduced.

Paul.