Date: Tue, 23 Jul 2013 17:21:08 -0400
From: Tejun Heo <tj@kernel.org>
To: Tang Chen <tangchen@cn.fujitsu.com>
Cc: tglx@linutronix.de, mingo@elte.hu, hpa@zytor.com,
        akpm@linux-foundation.org, trenn@suse.de, yinghai@kernel.org,
        jiang.liu@huawei.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com,
        isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com,
        mgorman@suse.de, minchan@kernel.org, mina86@mina86.com,
        gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com,
        lwoodman@redhat.com, riel@redhat.com, jweiner@redhat.com,
        prarit@redhat.com, zhangyanfei@cn.fujitsu.com, yanghy@cn.fujitsu.com,
        x86@kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-acpi@vger.kernel.org
Subject: Re: [PATCH 20/21] x86, numa, acpi, memory-hotplug: Make
 movablecore=acpi have higher priority.
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On Fri, Jul 19, 2013 at 03:59:33PM +0800, Tang Chen wrote:
> Arrange hotpluggable memory as ZONE_MOVABLE will cause NUMA performance down
> because the kernel cannot use movable memory. For users who don't use memory
> hotplug and who don't want to lose their NUMA performance, they need a way to
> disable this functionality. So we improved movablecore boot option.
> 
> If users specify the original movablecore=nn@ss boot option, the kernel will
> arrange [ss, ss+nn) as ZONE_MOVABLE. The kernelcore=nn@ss boot option is similar
> except it specifies ZONE_NORMAL ranges.
> 
> Now, if users specify "movablecore=acpi" in kernel commandline, the kernel will
> arrange hotpluggable memory in SRAT as ZONE_MOVABLE. And if users do this, all
> the other movablecore=nn@ss and kernelcore=nn@ss options should be ignored.
> 
> For those who don't want this, just specify nothing. The kernel will act as
> before.

As I wrote before, I find movablecore=acpi rather weird.  Shouldn't it
be memory_hotplug enable/disable switch instead and movablecore, if
specified, overriding information provided by firmware?

Thanks.

-- 
tejun
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