[PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[KOSAKI Motohiro]

Hi

this is a trivial bugfix.
I think this is not serious bug.
but if memcgroup reclaim change zone statics, global reclaim can confusion a bit.


================================================
memcg reclaim shouldn't change zone->recent_rotated statics.


Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Rik van Riel <riel@redhat.com>
---
 mm/vmscan.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: b/mm/vmscan.c
===================================================================
--- a/mm/vmscan.c	2008-11-24 06:20:24.000000000 +0900
+++ b/mm/vmscan.c	2008-11-25 01:29:16.000000000 +0900
@@ -1254,7 +1254,8 @@ static void shrink_active_list(unsigned 
 	 * This helps balance scan pressure between file and anonymous
 	 * pages in get_scan_ratio.
 	 */
-	zone->recent_rotated[!!file] += pgmoved;
+	if (scan_global_lru(sc))
+		zone->recent_rotated[!!file] += pgmoved;
 
 	/*
 	 * Move the pages to the [file or anon] inactive list.


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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[Rik van Riel]

KOSAKI Motohiro wrote:

> memcg reclaim shouldn't change zone->recent_rotated statics.
> 
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> CC: Rik van Riel <riel@redhat.com>

Acked-by: Rik van Riel <riel@redhat.com>

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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[Andrew Morton]

On Tue, 25 Nov 2008 12:22:53 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> +	if (scan_global_lru(sc))

mutter.  scan_global_lru() is a terrible function name.  Anyone reading
that code would expect that this function, umm, scans the global LRU.

gcc has a nice convention wherein such functions have a name ending in
"_p" (for "predicate").  Don't do this :)

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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[KOSAKI Motohiro]

> On Tue, 25 Nov 2008 12:22:53 +0900 (JST)
> KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> 
> > +	if (scan_global_lru(sc))
> 
> mutter.  scan_global_lru() is a terrible function name.  Anyone reading
> that code would expect that this function, umm, scans the global LRU.

yup.

> gcc has a nice convention wherein such functions have a name ending in
> "_p" (for "predicate").  Don't do this :)

however, "_p" isn't linux convention.
so, I like "is_" or "can_" (or likes somethingelse) prefix :)



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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[Alan Cox]

> however, "_p" isn't linux convention.
> so, I like "is_" or "can_" (or likes somethingelse) prefix :)

_p is from lisp but Ted did sneak tty_hung_up_p() into the kernel many
years ago.

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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[KOSAKI Motohiro]

> > however, "_p" isn't linux convention.
> > so, I like "is_" or "can_" (or likes somethingelse) prefix :)
> 
> _p is from lisp but Ted did sneak tty_hung_up_p() into the kernel many
> years ago.

Oh, you expose my knowledgeless ;-)



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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[KAMEZAWA Hiroyuki]

On Tue, 25 Nov 2008 15:54:22 -0800
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Tue, 25 Nov 2008 12:22:53 +0900 (JST)
> KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> 
> > +	if (scan_global_lru(sc))
> 
> mutter.  scan_global_lru() is a terrible function name.  Anyone reading
> that code would expect that this function, umm, scans the global LRU.
> 
> gcc has a nice convention wherein such functions have a name ending in
> "_p" (for "predicate").  Don't do this :)
> 

Hmm, I'll prepare renaming patch.

scan_global_lru_p() ? or under_scanning_global_lru() ?


Thanks,
-Kame

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Re: [PATCH] memcg reclaim shouldn't change zone->recent_rotated statics.

[Johannes Weiner]

On Thu, Nov 27, 2008 at 12:49:46PM +0900, KAMEZAWA Hiroyuki wrote:
> On Tue, 25 Nov 2008 15:54:22 -0800
> Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > On Tue, 25 Nov 2008 12:22:53 +0900 (JST)
> > KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> > 
> > > +	if (scan_global_lru(sc))
> > 
> > mutter.  scan_global_lru() is a terrible function name.  Anyone reading
> > that code would expect that this function, umm, scans the global LRU.
> > 
> > gcc has a nice convention wherein such functions have a name ending in
> > "_p" (for "predicate").  Don't do this :)
> > 
> 
> Hmm, I'll prepare renaming patch.
> 
> scan_global_lru_p() ?

That only works well when you don't have to use underscores, "listp"
or in Lisps where words can be hyphenated "loaded-module-p". 

But scan_global_lru_p() looks terrible.

> or under_scanning_global_lru() ?

How about just scanning_global_lru()?

	Hannes

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