linux-kernel - Re: Found the commit that causes the OOMs

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Message-ID: <2f11576a0906280801w417d1b9fpe10585b7a641d41b@mail.gmail.com>
Date:	Mon, 29 Jun 2009 00:01:40 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	Minchan Kim <minchan.kim@...il.com>,
	Johannes Weiner <hannes@...xchg.org>,
	David Howells <dhowells@...hat.com>,
	"riel@...hat.com" <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"tytso@....edu" <tytso@....edu>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"elladan@...imo.com" <elladan@...imo.com>,
	"npiggin@...e.de" <npiggin@...e.de>,
	"Barnes, Jesse" <jesse.barnes@...el.com>
Subject: Re: Found the commit that causes the OOMs

> Yes, smaller inactive_anon means smaller (pointless) nr_scanned,
> and therefore less slab scans. Strictly speaking, it's not the fault
> of your patch. It indicates that the slab scan ratio algorithm should
> be updated too :)

I don't think this patch is related to minchan's patch.
but I think this patch is good.


> We could refine the estimation of "reclaimable" pages like this:

hmhm, reasonable idea.

>
> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> index 416f748..e9c5b0e 100644
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -167,14 +167,7 @@ static inline unsigned long zone_page_state(struct zone *zone,
>  }
>
>  extern unsigned long global_lru_pages(void);
> -
> -static inline unsigned long zone_lru_pages(struct zone *zone)
> -{
> -       return (zone_page_state(zone, NR_ACTIVE_ANON)
> -               + zone_page_state(zone, NR_ACTIVE_FILE)
> -               + zone_page_state(zone, NR_INACTIVE_ANON)
> -               + zone_page_state(zone, NR_INACTIVE_FILE));
> -}
> +extern unsigned long zone_lru_pages(void);
>
>  #ifdef CONFIG_NUMA
>  /*
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 026f452..4281c6f 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2123,10 +2123,31 @@ void wakeup_kswapd(struct zone *zone, int order)
>
>  unsigned long global_lru_pages(void)
>  {
> -       return global_page_state(NR_ACTIVE_ANON)
> -               + global_page_state(NR_ACTIVE_FILE)
> -               + global_page_state(NR_INACTIVE_ANON)
> -               + global_page_state(NR_INACTIVE_FILE);
> +       int nr;
> +
> +       nr = global_page_state(zone, NR_ACTIVE_FILE) +
> +            global_page_state(zone, NR_INACTIVE_FILE);
> +
> +       if (total_swap_pages)
> +               nr += global_page_state(zone, NR_ACTIVE_ANON) +
> +                     global_page_state(zone, NR_INACTIVE_ANON);
> +
> +       return nr;
> +}

Please change function name too.
Now, this function only account reclaimable pages.

Plus, total_swap_pages is bad. if we need to concern "reclaimable
pages", we should use nr_swap_pages.
I mean, swap-full also makes anon is unreclaimable althouth system
have sone swap device.



> +
> +
> +unsigned long zone_lru_pages(struct zone *zone)
> +{
> +       int nr;
> +
> +       nr = zone_page_state(zone, NR_ACTIVE_FILE) +
> +            zone_page_state(zone, NR_INACTIVE_FILE);
> +
> +       if (total_swap_pages)
> +               nr += zone_page_state(zone, NR_ACTIVE_ANON) +
> +                     zone_page_state(zone, NR_INACTIVE_ANON);
> +
> +       return nr;
>  }
>
>  #ifdef CONFIG_HIBERNATION
>
> --
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