Re: [PATCH 0/4] Swap migration V3: Overview

[mike kravetz <kravetz@us.ibm.com>]

On Fri, Oct 21, 2005 at 12:22:06PM +0900, KAMEZAWA Hiroyuki wrote:
> mike kravetz wrote:
> >On Thu, Oct 20, 2005 at 04:06:38PM -0700, Andrew Morton wrote:
> 
> >Just to be clear, there are at least two distinct requirements for hotplug.
> >One only wants to remove a quantity of memory (location unimportant).  The
> >other wants to remove a specific section of memory (location specific).  I
> >think the first is easier to address.
> >
> 
> The only difficulty to remove a quantity of memory is how to find
> where is easy to be removed. If this is fixed, I think it is
> easier to address.

We have been using Mel's fragmentation patches.  One of the data structures
created by these patches is a 'usemap' thats tracks how 'blocks' of memory
are used.  I exposed the usemaps via sysfs along with other hotplug memory
section attributes.  So, you can then have a user space program scan the
usemaps looking for sections that can be easily offlined.

-- 
Mike

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