Re: [PATCH 5/5] Swapless V2: Revise main migration logic

From: KAMEZAWA Hiroyuki
Date: Thu Apr 13 2006 - 21:19:33 EST



On Thu, 13 Apr 2006 16:54:32 -0700 (PDT)
Christoph Lameter <clameter@xxxxxxx> wrote:

>
> + inc_mm_counter(mm, anon_rss);
> + get_page(new);
> + set_pte_at(mm, addr, ptep, pte_mkold(mk_pte(new, vma->vm_page_prot)));
> + page_add_anon_rmap(new, vma, addr);

Just a note:

This will cause unecessary copy-on-write later.
(current remove_from_swap() can cause copy-on-write....)
But maybe copy-on-write is just minor case for migrating specified vmas.

For hotremove (I stops it now..), we should fix this later (if we can do).
If new SWP_TYPE_MIGRATION swp entry can contain write protect bit,
hotremove can avoid copy-on-write but things will be more complicated.

-Kame

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