Re: [PATCH 0/2] Page migration via Swap V2: Overview

Christoph Lameter
2005-10-18T16:50:45Z

On Tue, 18 Oct 2005, KAMEZAWA Hiroyuki wrote:

> Because sys_mbind() acquires mm->mmap_sem, once page is unmapped,
> all accesses to the page are blocked.
>
> So, even if the range contains hot pages, there will not be
> hard-to-be-swapped-out pages. right ?

There may be locked pages and maybe pages that are continually busy.

> sys_mbind() can aquire mm->mmap_sem for migrating *a process's page*,
> but memory-hotplug cannot aquire the lock for migrating a chunk of pages.

I did mbind first because it is the less invasive. The primary reason to
acquire mmap_sem is to be able to walk the vma areas.

> I think we'll need radix_tree_replace for migating arbitrary chunk of pages,
> anyway.

Likely. Ultimately I would like to see the direct migration work.