Date: Sat, 23 Feb 2008 00:04:48 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: "David S. Miller" <davem@davemloft.net>,
       linux kernel <linux-kernel@vger.kernel.org>, netdev@vger.kernel.org,
       Christoph Lameter <clameter@sgi.com>,
       "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Subject: Re: [PATCH] alloc_percpu() fails to allocate percpu data
Message-Id: <20080223000448.9dadd2c5.akpm@linux-foundation.org>
In-Reply-To: <47BDBC23.10605@cosmosbay.com>
References: <47BDBC23.10605@cosmosbay.com>
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On Thu, 21 Feb 2008 19:00:03 +0100 Eric Dumazet <dada1@cosmosbay.com> wrote:

> +#ifndef cache_line_size
> +#define cache_line_size()	L1_CACHE_BYTES
> +#endif

argh, you made me look.

Really cache_line_size() should be implemented in include/linux/cache.h. 
Then we tromp the stupid private implementations in slob.c and slub.c.

Then we wonder why x86 uses a custom cache_line_size(), but still uses
L1_CACHE_BYTES for its L1_CACHE_ALIGN().

Once we've answered that, we look at your

+	/*
+	 * We should make sure each CPU gets private memory.
+	 */
+	size = roundup(size, cache_line_size());

and wonder whether it should have used L1_CACHE_ALIGN().

I think I'd better stop looking.
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