linux-kernel - Re: [PATCH 3/3] Provide control over unmapped pages (v4)

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Message-ID: <20110128120247.GE5054@balbir.in.ibm.com>
Date:	Fri, 28 Jan 2011 17:32:47 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Minchan Kim <minchan.kim@...il.com>, linux-mm@...ck.org,
	akpm@...ux-foundation.org, npiggin@...nel.dk, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, kosaki.motohiro@...fujitsu.com,
	cl@...ux.com
Subject: Re: [PATCH 3/3] Provide control over unmapped pages (v4)

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2011-01-28 17:17:44]:

> On Fri, 28 Jan 2011 13:49:28 +0530
> Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> 
> > * KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2011-01-28 16:56:05]:
> 
> > > BTW, it seems this doesn't work when some apps use huge shmem.
> > > How to handle the issue ?
> > >
> > 
> > Could you elaborate further? 
> > 
> ==
> static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
> {
>         unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
>         unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) +
>                 zone_page_state(zone, NR_ACTIVE_FILE);
> 
>         /*
>          * It's possible for there to be more file mapped pages than
>          * accounted for by the pages on the file LRU lists because
>          * tmpfs pages accounted for as ANON can also be FILE_MAPPED
>          */
>         return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
> }

Yes, I did :) The word huge confused me. I am not sure if there is an
easy accounting fix for this one, though given the approximate nature
of the control, I am not sure it would matter very much. But you do
have a very good point.

-- 
	Three Cheers,
	Balbir
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