Re: [RFC][PATCH] migrate_pages:skip migration between intersect nodes

[Bob Liu <lliubbo@gmail.com>]

On 3/31/10, Minchan Kim <minchan.kim@gmail.com> wrote:
> On Wed, Mar 31, 2010 at 10:36 AM, Bob Liu <lliubbo@gmail.com> wrote:
>> On 3/31/10, Christoph Lameter <cl@linux-foundation.org> wrote:
>>> On Tue, 30 Mar 2010, Minchan Kim wrote:
>>>
>>>> Hi, Bob
>>>>
>>>> On Mon, Mar 29, 2010 at 11:57 PM, Bob Liu <lliubbo@gmail.com> wrote:
>>>> > In current do_migrate_pages(),if from_nodes and to_nodes have some
>>>> > intersect nodes,pages in these intersect nodes will also be
>>>> > migrated.
>>>> > eg. Assume that, from_nodes: 1,2,3,4 to_nodes: 2,3,4,5. Then these
>>>> > migrates will happen:
>>>> > migrate_pages(4,5);
>>>> > migrate_pages(3,4);
>>>> > migrate_pages(2,3);
>>>> > migrate_pages(1,2);
>>>> >
>>>> > But the user just want all pages in from_nodes move to to_nodes,
>>>> > only migrate(1,2)(ignore the intersect nodes.) can satisfied
>>>> > the user's request.
>>>> >
>>>> > I amn't sure what's migrate_page's semantic.
>>>> > Hoping for your suggestions.
>>>>
>>>> I didn't see 8:migratepages Lee pointed at that time.
>>>> The description matches current migrate_pages's behavior exactly.
>>>>
>>>> I agree Lee's opinion.
>>>> Let's wait Christoph's reply what is semantic
>>>> and why it doesn't have man page.
>>>
>>> Manpage is part of numatools.
>>>
>>> The intended semantic is the preservation of the relative position of the
>>> page to the beginning of the node set. If you do not want to preserve the
>>> relative position then just move portions of the nodes around.
>>>
>>
>> Hmm.,
>> Sorry I still haven't understand your mention :-)
>>
>> My concern was why move the pages in the intersect nodes.I think skipping
>> this migration we can also satisfy the user's request.
>> In the above semantic, I  haven't got the result.
>>
>
> man page said.
>
> "For example if we move from nodes 2-5 to 7,9,12-13 then the preferred mode
> of
> operation is to move pages from 2->7, 3->9, 4->12 and 5->13. However, this
> is only posssible if enough memory is available."
>
> If user uses migratepages((1,2,3,4), (2,3,4,5)), He want to move pages
> (1->2), (2-3), (3->4), (4-5). It matches with magpage.
>
> But with your suggestion, only (1-2).
> I think It doesn't match with man page.
>

Ok. I got it.. I used to didn't find numatools.

Thanks all!

> Do you want to add some words to make manpage more clear?
>
>> Thanks!
>> --
>> Regards,
>> -Bob
>>
>
>
>
> --
> Kind regards,
> Minchan Kim
>


-- 
Regards,
--Bob

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