Re: [PATCH 3/7] mm: rework __isolate_lru_page() file/anon filter

[Konstantin Khlebnikov]

KAMEZAWA Hiroyuki wrote:
> On Fri, 02 Mar 2012 09:51:27 +0400
> Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>  wrote:
>
> > KAMEZAWA Hiroyuki wrote:
> > > On Wed, 29 Feb 2012 13:15:47 +0400
> > > Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>   wrote:
> > >
> > > > This patch adds file/anon filter bits into isolate_mode_t,
> > > > this allows to simplify checks in __isolate_lru_page().
> > > >
> > > > Signed-off-by: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
> > >
> > > Hmm.. I like idea but..
> > >
> > > > ---
> > > >    include/linux/mmzone.h |    4 ++++
> > > >    include/linux/swap.h   |    2 +-
> > > >    mm/compaction.c        |    5 +++--
> > > >    mm/vmscan.c            |   27 +++++++++++++--------------
> > > >    4 files changed, 21 insertions(+), 17 deletions(-)
> > > >
> > > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> > > > index eff4918..2fed935 100644
> > > > --- a/include/linux/mmzone.h
> > > > +++ b/include/linux/mmzone.h
> > > > @@ -193,6 +193,10 @@ struct lruvec {
> > > >    #define ISOLATE_UNMAPPED	((__force isolate_mode_t)0x8)
> > > >    /* Isolate for asynchronous migration */
> > > >    #define ISOLATE_ASYNC_MIGRATE	((__force isolate_mode_t)0x10)
> > > > +/* Isolate swap-backed pages */
> > > > +#define	ISOLATE_ANON		((__force isolate_mode_t)0x20)
> > > > +/* Isolate file-backed pages */
> > > > +#define	ISOLATE_FILE		((__force isolate_mode_t)0x40)
> > > >
> > > >    /* LRU Isolation modes. */
> > > >    typedef unsigned __bitwise__ isolate_mode_t;
> > > > diff --git a/include/linux/swap.h b/include/linux/swap.h
> > > > index ba2c8d7..dc6e6a3 100644
> > > > --- a/include/linux/swap.h
> > > > +++ b/include/linux/swap.h
> > > > @@ -254,7 +254,7 @@ static inline void lru_cache_add_file(struct page *page)
> > > >    /* linux/mm/vmscan.c */
> > > >    extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> > > >    					gfp_t gfp_mask, nodemask_t *mask);
> > > > -extern int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file);
> > > > +extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
> > > >    extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
> > > >    						  gfp_t gfp_mask, bool noswap);
> > > >    extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
> > > > diff --git a/mm/compaction.c b/mm/compaction.c
> > > > index 74a8c82..cc054f7 100644
> > > > --- a/mm/compaction.c
> > > > +++ b/mm/compaction.c
> > > > @@ -261,7 +261,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
> > > >    	unsigned long last_pageblock_nr = 0, pageblock_nr;
> > > >    	unsigned long nr_scanned = 0, nr_isolated = 0;
> > > >    	struct list_head *migratelist =&cc->migratepages;
> > > > -	isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE;
> > > > +	isolate_mode_t mode = ISOLATE_ACTIVE | ISOLATE_INACTIVE |
> > > > +			      ISOLATE_FILE | ISOLATE_ANON;
> > > >
> > > >    	/* Do not scan outside zone boundaries */
> > > >    	low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
> > > > @@ -375,7 +376,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
> > > >    			mode |= ISOLATE_ASYNC_MIGRATE;
> > > >
> > > >    		/* Try isolate the page */
> > > > -		if (__isolate_lru_page(page, mode, 0) != 0)
> > > > +		if (__isolate_lru_page(page, mode) != 0)
> > > >    			continue;
> > > >
> > > >    		VM_BUG_ON(PageTransCompound(page));
> > > > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > > > index af6cfe7..1b70338 100644
> > > > --- a/mm/vmscan.c
> > > > +++ b/mm/vmscan.c
> > > > @@ -1029,27 +1029,18 @@ keep_lumpy:
> > > >     *
> > > >     * returns 0 on success, -ve errno on failure.
> > > >     */
> > > > -int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file)
> > > > +int __isolate_lru_page(struct page *page, isolate_mode_t mode)
> > > >    {
> > > > -	bool all_lru_mode;
> > > >    	int ret = -EINVAL;
> > > >
> > > >    	/* Only take pages on the LRU. */
> > > >    	if (!PageLRU(page))
> > > >    		return ret;
> > > >
> > > > -	all_lru_mode = (mode&   (ISOLATE_ACTIVE|ISOLATE_INACTIVE)) ==
> > > > -		(ISOLATE_ACTIVE|ISOLATE_INACTIVE);
> > > > -
> > > > -	/*
> > > > -	 * When checking the active state, we need to be sure we are
> > > > -	 * dealing with comparible boolean values.  Take the logical not
> > > > -	 * of each.
> > > > -	 */
> > > > -	if (!all_lru_mode&&   !PageActive(page) != !(mode&   ISOLATE_ACTIVE))
> > > > +	if (!(mode&   (PageActive(page) ? ISOLATE_ACTIVE : ISOLATE_INACTIVE)))
> > > >    		return ret;
> > >
> > > Isn't this complicated ?
> >
> > But it doesn't blows my mind as old code does =)
> >
> > Maybe someone can propose more clear variant?
>
> switch (mode&  (ISOLATE_ACTIVE | ISOLATE_INACTIVE)) {
> 	case ISOLATE_ACTIVE :
> 		if (!PageActive(page))
> 			return ret;
> 	case ISOLATE_INACTIVE :
> 		if (PageActive(page))
> 			return ret;
> 	default:
> 		break;
> 	}
> }
>
> ?

Thanks. It is more optimal and looks more simple. but you lost one "break"

> Thanks,
> -Kame
>
> > > > -	if (!all_lru_mode&&   !!page_is_file_cache(page) != file)
> > > > +	if (!(mode&   (page_is_file_cache(page) ? ISOLATE_FILE : ISOLATE_ANON)))
> > > >    		return ret;
> > > >
> > > >    	/*
> > >
> > > ditto.
> > >
> > > Where is simple  ?
> > >
> > > Thanks,
> > > -Kame
> >
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