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From: Tejun Heo <tj@kernel.org>
To: Shaohua Li <shaohua.li@intel.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	cl@linux.com
Subject: Re: [PATCH 3/4]percpu_counter: fix code for 32bit systems
Date: Wed, 13 Apr 2011 04:02:51 +0900	[thread overview]
Message-ID: <20110412190251.GD16342@mtj.dyndns.org> (raw)
In-Reply-To: <1302595444.3981.129.camel@sli10-conroe>

On Tue, Apr 12, 2011 at 04:04:04PM +0800, Shaohua Li wrote:
>  static inline s64 percpu_counter_read(struct percpu_counter *fbc)
>  {
> +#if BITS_PER_LONG == 32
> +	s64 count;
> +	spin_lock(&fbc->lock);
> +	count = fbc->count;
> +	spin_unlock(&fbc->lock);
> +	return count;
> +#else
>  	return fbc->count;
> +#endif

I don't know.  Is there any problem caused by this?  The interface is
known to be unreliable and already being used in speculative manner.
I think it's more beneficial to avoid using locks on fast read path.

Thanks.

-- 
tejun

  parent reply	other threads:[~2011-04-12 19:03 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-12  8:04 Shaohua Li
2011-04-12  9:03 ` Eric Dumazet
2011-04-13  1:01   ` Shaohua Li
2011-04-13  2:32     ` Eric Dumazet
2011-04-13  2:41       ` Shaohua Li
2011-04-13  2:47         ` Eric Dumazet
2011-04-13  3:03           ` Shaohua Li
2011-04-13  3:50             ` tj
2011-04-13  4:37               ` Shaohua Li
2011-04-13  3:53             ` Eric Dumazet
2011-04-13  4:00               ` tj
2011-04-12 19:02 ` Tejun Heo [this message]
2011-04-13  1:05   ` Shaohua Li

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