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

>
>>
>> - 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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