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

>
> - 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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