linux-kernel - Re: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned memory is bad

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Message-Id: <20080328121758.7f355925.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Fri, 28 Mar 2008 12:17:58 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Yasunori Goto <y-goto@...fujitsu.com>, Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Christoph Lameter <clameter@....com>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned
 memory is bad

On Thu, 27 Mar 2008 19:51:26 -0700
Jeremy Fitzhardinge <jeremy@...p.org> wrote:

> > (I wrote online_page() in above, but online_pages() is maybe better.
> >  It does all what you want.)
> >   
> 
> No, for my use-case the pages must be onlined one by one as they get 
> some physical memory assigned to them.  At the time I do add_memory(), 
> I'm just allocating page structures, but there's no memory backing that 
> range.
> 
yes, I see.

> That's why I need to disable the sysfs onlining interface, because it 
> bulk onlines the pages before there's anything behind them.
>

My point is. online_pages() does following things.

- call notifier
- update information , total_pages etc...
- re-configure zonelist if necessary...

But online_page() not. Hmm...

How about capturing online_page() by balloon ?
ex.)
==
call add_memory() to create mem_map
call online_pages() against the whole section. <=== call this without sysfs.
     online_pages() do misc. jobs
        call online_page() one by one (arch dependent) called by walk_memory_resource.
            online_page() will finally call free_page(page).
            <=========== Xen capture here.
            Don't free onlined page and swallow them into baloon driver.
==

Thanks,
-Kame

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