From: Hekuang <hekuang@huawei.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz,
rientjes@google.com, cody@linux.vnet.ibm.com,
gilad@benyossef.com, kosaki.motohiro@gmail.com, mgorman@suse.de,
penberg@kernel.org, lizefan@huawei.com, wangnan0@huawei.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE"
Date: Wed, 30 Mar 2016 18:51:12 +0800 [thread overview]
Message-ID: <56FBAFA0.3010604@huawei.com> (raw)
In-Reply-To: <20160330103839.GA4773@techsingularity.net>
hi
a?? 2016/3/30 18:38, Mel Gorman a??e??:
> On Wed, Mar 30, 2016 at 10:22:07AM +0000, He Kuang wrote:
>> This reverts commit 998d39cb236fe464af86a3492a24d2f67ee1efc2.
>>
>> When local irq is disabled, a percpu variable does not change, so we can
>> remove the access macros and let the compiler optimize the code safely.
>>
> batch can be changed from other contexts. Why is this safe?
>
I've mistakenly thought that per_cpu variable can only be accessed by
that cpu.
Thanks.
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WARNING: multiple messages have this Message-ID (diff)
From: Hekuang <hekuang@huawei.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: <akpm@linux-foundation.org>, <mhocko@suse.com>, <vbabka@suse.cz>,
<rientjes@google.com>, <cody@linux.vnet.ibm.com>,
<gilad@benyossef.com>, <kosaki.motohiro@gmail.com>,
<mgorman@suse.de>, <penberg@kernel.org>, <lizefan@huawei.com>,
<wangnan0@huawei.com>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Revert "mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE"
Date: Wed, 30 Mar 2016 18:51:12 +0800 [thread overview]
Message-ID: <56FBAFA0.3010604@huawei.com> (raw)
In-Reply-To: <20160330103839.GA4773@techsingularity.net>
hi
在 2016/3/30 18:38, Mel Gorman 写道:
> On Wed, Mar 30, 2016 at 10:22:07AM +0000, He Kuang wrote:
>> This reverts commit 998d39cb236fe464af86a3492a24d2f67ee1efc2.
>>
>> When local irq is disabled, a percpu variable does not change, so we can
>> remove the access macros and let the compiler optimize the code safely.
>>
> batch can be changed from other contexts. Why is this safe?
>
I've mistakenly thought that per_cpu variable can only be accessed by
that cpu.
Thanks.
next prev parent reply other threads:[~2016-03-30 10:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 10:22 [PATCH] Revert "mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE" He Kuang
2016-03-30 10:22 ` He Kuang
2016-03-30 10:38 ` Mel Gorman
2016-03-30 10:38 ` Mel Gorman
2016-03-30 10:51 ` Hekuang [this message]
2016-03-30 10:51 ` Hekuang
2016-03-30 11:10 ` Michal Hocko
2016-03-30 11:10 ` Michal Hocko
2016-03-31 1:14 ` Hekuang
2016-03-31 1:14 ` Hekuang
2016-03-31 1:39 ` Zefan Li
2016-03-31 1:39 ` Zefan Li
2016-03-31 1:47 ` Hekuang
2016-03-31 1:47 ` Hekuang
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