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Message-ID: <462932BE.4020005@redhat.com>
Date: Fri, 20 Apr 2007 17:38:06 -0400
From: Rik van Riel <riel@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: linux-kernel <linux-kernel@...r.kernel.org>,
linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH] lazy freeing of memory through MADV_FREE
Andrew Morton wrote:
> I've also merged Nick's "mm: madvise avoid exclusive mmap_sem".
>
> - Nick's patch also will help this problem. It could be that your patch
> no longer offers a 2x speedup when combined with Nick's patch.
>
> It could well be that the combination of the two is even better, but it
> would be nice to firm that up a bit.
I'll test that.
> I do go on about that. But we're adding page flags at about one per
> year, and when we run out we're screwed - we'll need to grow the
> pageframe.
If you want, I can take a look at folding this into the
->mapping pointer. I can guarantee you it won't be
pretty, though :)
> - I need to update your patch for Nick's patch. Please confirm that
> down_read(mmap_sem) is sufficient for MADV_FREE.
It is. MADV_FREE needs no more protection than MADV_DONTNEED.
> Stylistic nit:
>
>> + if (PageLazyFree(page) && !migration) {
>> + /* There is new data in the page. Reinstate it. */
>> + if (unlikely(pte_dirty(pteval))) {
>> + set_pte_at(mm, address, pte, pteval);
>> + ret = SWAP_FAIL;
>> + goto out_unmap;
>> + }
>
> The comment should be inside the second `if' statement. As it is, It
> looks like we reinstate the page if (PageLazyFree(page) && !migration).
Want me to move it?
--
Politics is the struggle between those who want to make their country
the best in the world, and those who believe it already is. Each group
calls the other unpatriotic.
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