Message-ID: <5209CEC1.8070908@cn.fujitsu.com>
Date: Tue, 13 Aug 2013 14:14:25 +0800
From: Tang Chen <tangchen@cn.fujitsu.com>
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To: Tejun Heo <tj@kernel.org>
CC: Tang Chen <imtangchen@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>,
        robert.moore@intel.com, lv.zheng@intel.com, rjw@sisk.pl,
        lenb@kernel.org, tglx@linutronix.de, mingo@elte.hu,
        akpm@linux-foundation.org, trenn@suse.de, yinghai@kernel.org,
        jiang.liu@huawei.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com,
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        mgorman@suse.de, minchan@kernel.org, mina86@mina86.com,
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        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,
        "Luck, Tony (tony.luck@intel.com)" <tony.luck@intel.com>
Subject: Re: [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE.
References: <1375956979-31877-1-git-send-email-tangchen@cn.fujitsu.com> <20130812145016.GI15892@htj.dyndns.org> <5208FBBC.2080304@zytor.com> <20130812152343.GK15892@htj.dyndns.org> <52090D7F.6060600@gmail.com> <20130812164650.GN15892@htj.dyndns.org>
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On 08/13/2013 12:46 AM, Tejun Heo wrote:
......
>
> * Adding an option to tell the kernel to try to stay away from
>    hotpluggable nodes is fine.  I have no problem with that at all.
>
> * The patchsets upto this point have been somehow trying to reorder
>    operations shomehow such that *no* memory allocation happens before
>    memblock is populated with hotplug information.
>
> * However, we already *know* that the memory the kernel image is
>    occupying won't be removeable.  It's highly likely that the amount
>    of memory allocation before NUMA / hotplug information is fully
>    populated is pretty small.  Also, it's highly likely that small
>    amount of memory right after the kernel image is contained in the
>    same NUMA node, so if we allocate memory close to the kernel image,
>    it's likely that we don't contaminate hotpluggable node.  We're
>    talking about few megs at most right after the kernel image.  I
>    can't see how that would make any noticeable difference.
>
> * Once hotplug information is available, allocation can happen as
>    usual and the kernel can report the nodes which are actually
>    hotpluggable - marked as hotpluggable by the firmware&&  didn't get
>    contaminated during early alloc&&  didn't get overflow allocations
>    afterwards.  Note that we need such mechanism no matter what as the
>    kernel image can be loaded into hotpluggable nodes and reporting
>    that to userland is the only thing the kernel can do for cases like
>    that short of denying memory unplug on such nodes.
>

Hi tj, hpa, luck, yinghai,

So if all of you agree on the idea above from tj, I think
we can do it in this way. Will update the patches to allocate
memory near kernel image before SRAT is parsed.

Thanks.
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