From: Shaohua Li <shaohua.li@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>, linux-mm <linux-mm@kvack.org>,
lkml <linux-kernel@vger.kernel.org>,
Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH]mmap: add alignment for some variables
Date: Wed, 30 Mar 2011 09:54:01 +0800 [thread overview]
Message-ID: <1301450041.3981.55.camel@sli10-conroe> (raw)
In-Reply-To: <20110329184110.0086924e.akpm@linux-foundation.org>
On Wed, 2011-03-30 at 09:41 +0800, Andrew Morton wrote:
> On Wed, 30 Mar 2011 09:36:40 +0800 Shaohua Li <shaohua.li@intel.com> wrote:
>
> > > how is it that this improves things?
> > Hmm, it actually is:
> > struct percpu_counter {
> > spinlock_t lock;
> > s64 count;
> > #ifdef CONFIG_HOTPLUG_CPU
> > struct list_head list; /* All percpu_counters are on a list */
> > #endif
> > s32 __percpu *counters;
> > } __attribute__((__aligned__(1 << (INTERNODE_CACHE_SHIFT))))
> > so lock and count are in one cache line.
>
> ____cacheline_aligned_in_smp would achieve that?
____cacheline_aligned_in_smp can't guarantee the cache alignment for
multiple nodes, because the variable can be updated by multiple
nodes/cpus.
Thanks,
Shaohua
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next prev parent reply other threads:[~2011-03-30 1:54 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-28 1:58 [PATCH]mmap: add alignment for some variables Shaohua Li
2011-03-28 16:55 ` Andi Kleen
2011-03-29 0:54 ` Shaohua Li
2011-03-29 22:24 ` Andrew Morton
2011-03-29 22:38 ` Christoph Lameter
2011-03-30 1:01 ` Shaohua Li
2011-03-30 1:06 ` Andrew Morton
2011-03-30 1:17 ` Shaohua Li
2011-03-30 1:25 ` Andrew Morton
2011-03-30 1:36 ` Shaohua Li
2011-03-30 1:41 ` Andrew Morton
2011-03-30 1:54 ` Shaohua Li [this message]
2011-03-30 2:10 ` Andrew Morton
2011-03-30 2:35 ` Shaohua Li
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