Re: [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE.

[Tang Chen <tangchen@cn.fujitsu.com>]

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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