From: Glauber Costa <glommer@parallels.com>
To: Wanpeng Li <liwp.linux@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>,
Balbir Singh <bsingharora@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Gavin Shan <shangw@linux.vnet.ibm.com>
Subject: Re: [PATCH] mm/memcg: add unlikely to mercg->move_charge_at_immigrate
Date: Mon, 18 Jun 2012 17:19:18 +0400 [thread overview]
Message-ID: <4FDF2AD6.7060606@parallels.com> (raw)
In-Reply-To: <20120618131918.GA2600@kernel>
On 06/18/2012 05:19 PM, Wanpeng Li wrote:
> On Mon, Jun 18, 2012 at 05:09:36PM +0400, Glauber Costa wrote:
>> On 06/18/2012 05:10 PM, Wanpeng Li wrote:
>>> From: Wanpeng Li <liwp@linux.vnet.ibm.com>
>>>
>>> move_charge_at_immigrate feature is disabled by default. Charges
>>> are moved only when you move mm->owner and it also add additional
>>> overhead.
>>
>> How big is this overhead?
>>
>> That's hardly a fast path. And if it happens to matter, it will be
>> just bigger when you enable it, and the compiler start giving the
>> wrong hints to the code.
>
> Thank you for your quick response.
>
> Oh, Maybe I should just write comments "move_charge_at_immigrate feature
> is disabled by default. So add "unlikely", in order to compiler can optimize."
>
Again, do you have any reason to optimize that ?
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next prev parent reply other threads:[~2012-06-18 13:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-18 13:10 Wanpeng Li
2012-06-18 13:09 ` Glauber Costa
2012-06-18 13:19 ` Wanpeng Li
2012-06-18 13:19 ` Glauber Costa [this message]
2012-06-19 0:02 ` Kamezawa Hiroyuki
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