linux-kernel - Re: [PATCH 2/5] add buffer cache information to show_free

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Message-Id: <20090705202503.0914.A69D9226@jp.fujitsu.com>
Date:	Sun,  5 Jul 2009 20:31:02 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH 2/5] add buffer cache information to show_free_areas()

> On Sun, Jul 05, 2009 at 05:24:07PM +0800, KOSAKI Motohiro wrote:
> > Subject: [PATCH] add buffer cache information to show_free_areas()
> > 
> > When administrator analysis memory shortage reason from OOM log, They
> > often need to know rest number of cache like pages.
> 
> nr_blockdev_pages() pages are also accounted in NR_FILE_PAGES.

Yes, I know.

> > Then, show_free_areas() shouldn't only display page cache, but also it
> > should display buffer cache.
> 
> So if we are to add this, I'd suggest to put it close to the total
> pagecache line:
> 
>         printk("%ld total pagecache pages\n", global_page_state(NR_FILE_PAGES));
> +       printk("%ld blkdev pagecache pages\n", nr_blockdev_pages());

but this is intensional. May I explain why I choose non verbose area?
In typical workload, buffer-pages doesn't consume so many pages. then
I feel that your idea is too verbose output. In addition, if buffer-pages are much,
Administrator want to know other I/O related vmstat at the same time.

Then, I choose current position.


Thanks.



> 
> Thanks,
> Fengguang
> 
> > 
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> > ---
> >  mm/page_alloc.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > Index: b/mm/page_alloc.c
> > ===================================================================
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -2118,7 +2118,7 @@ void show_free_areas(void)
> >  	printk("Active_anon:%lu active_file:%lu inactive_anon:%lu\n"
> >  		" inactive_file:%lu"
> >  		" unevictable:%lu"
> > -		" dirty:%lu writeback:%lu unstable:%lu\n"
> > +		" dirty:%lu writeback:%lu buffer:%lu unstable:%lu\n"
> >  		" free:%lu slab_reclaimable:%lu slab_unreclaimable:%lu\n"
> >  		" mapped:%lu pagetables:%lu bounce:%lu\n",
> >  		global_page_state(NR_ACTIVE_ANON),
> > @@ -2128,6 +2128,7 @@ void show_free_areas(void)
> >  		global_page_state(NR_UNEVICTABLE),
> >  		global_page_state(NR_FILE_DIRTY),
> >  		global_page_state(NR_WRITEBACK),
> > +		K(nr_blockdev_pages()),
> >  		global_page_state(NR_UNSTABLE_NFS),
> >  		global_page_state(NR_FREE_PAGES),
> >  		global_page_state(NR_SLAB_RECLAIMABLE),
> > 



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