linux-kernel - Re: [RFC 2/2] Prevent promotion of page in madvise

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Message-ID: <AANLkTimm9KzAYBecikb4WqnRCo-Gw5eJdSD5dhX5ObYa@mail.gmail.com>
Date:	Tue, 23 Nov 2010 13:57:17 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Nick Piggin <npiggin@...nel.dk>
Subject: Re: [RFC 2/2] Prevent promotion of page in madvise_dontneed

On Tue, Nov 23, 2010 at 7:21 AM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Sun, 21 Nov 2010 23:30:24 +0900
> Minchan Kim <minchan.kim@...il.com> wrote:
>
>> Now zap_pte_range alwayas promotes pages which are pte_young &&
>> !VM_SequentialReadHint(vma). But in case of calling MADV_DONTNEED,
>> it's unnecessary since the page wouldn't use any more.
>>
>> If the page is sharred by other processes and it's real working set
>
> This patch doesn't actually do anything.  It passes variable `promote'
> all the way down to unmap_vmas(), but unmap_vmas() doesn't use that new
> variable.

Oops. Sorry for that.
I will resend the patch with your fixlet and Ben's point.
Thank you.

> Have a comment fixlet:
>
> --- a/mm/memory.c~mm-prevent-promotion-of-page-in-madvise_dontneed-fix
> +++ a/mm/memory.c
> @@ -1075,7 +1075,7 @@ static unsigned long unmap_page_range(st
>  * @end_addr: virtual address at which to end unmapping
>  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
>  * @details: details of nonlinear truncation or shared cache invalidation
> - * @promote: whether pages inclued vma would be promoted or not
> + * @promote: whether pages included in the vma should be promoted or not
>  *
>  * Returns the end address of the unmapping (restart addr if interrupted).
>  *
> _
>
> Also, I'd suggest that we avoid introducing the term "promote".  It
> isn't a term which is presently used in Linux MM.  Probably "activate"
> has a better-known meaning.
>
> And `activate' could be a bool if one is in the mood for that.
>



-- 
Kind regards,
Minchan Kim
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