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SubjectRe: [PATCH 3/7] mm: rework __isolate_lru_page() file/anon filter
On Fri, 02 Mar 2012 09:51:27 +0400
Konstantin Khlebnikov <khlebnikov@openvz.org> wrote:

> KAMEZAWA Hiroyuki wrote:
> > On Wed, 29 Feb 2012 13:15:47 +0400
> > Konstantin Khlebnikov<khlebnikov@openvz.org> 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@openvz.org>
> >
> > 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,
-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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