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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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