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Date: Fri, 02 Mar 2012 10:11:18 +0400
From: Konstantin Khlebnikov <khlebnikov@...nvz.org>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
CC: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
Johannes Weiner <jweiner@...hat.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/7] mm: rework reclaim_stat counters
KAMEZAWA Hiroyuki wrote:
> On Wed, 29 Feb 2012 13:15:56 +0400
> Konstantin Khlebnikov<khlebnikov@...nvz.org> wrote:
>
>> Currently there is two types of reclaim-stat counters:
>> recent_scanned (pages picked from from lru),
>> recent_rotated (pages putted back to active lru).
>> Reclaimer uses ratio recent_rotated / recent_scanned
>> for balancing pressure between file and anon pages.
>>
>> But if we pick page from lru we can either reclaim it or put it back to lru, thus:
>> recent_scanned == recent_rotated[inactive] + recent_rotated[active] + reclaimed
>> This can be called "The Law of Conservation of Memory" =)
>>
> I'm sorry....where is the count for active->incative ?
If reclaimer deactivates page it will bump recent_rotated[LRU_INACTIVE_ANON/FILE],
(if I understand your question right) recent_rotated[] now count each evictable lru independently
>
>
>
>> Thus recent_rotated counters for each lru list is enough, reclaimed pages can be
>> counted as rotatation into inactive lru. After that reclaimer can use this ratio:
>> recent_rotated[active] / (recent_rotated[active] + recent_rotated[inactive])
>>
>> After this patch struct zone_reclaimer_stat has only one array: recent_rotated,
>> which is directly indexed by lru list index.
>>
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@...nvz.org>
>
> I'm sorry if I misunderstand..
> Recent_scanned can be update by some logics other than vmscan..
>
> For example, how lru_deactivate_fn() is handled ?
It increase recent_rotated[LRU_INACTIVE_ANON/LRU_INACTIVE_FILE]
>
> Thanks,
> -Kame
>
>
>
>
>> ---
>> include/linux/mmzone.h | 11 +++++------
>> mm/memcontrol.c | 29 +++++++++++++++++------------
>> mm/page_alloc.c | 6 ++----
>> mm/swap.c | 26 ++++++++------------------
>> mm/vmscan.c | 42 ++++++++++++++++++++++--------------------
>> 5 files changed, 54 insertions(+), 60 deletions(-)
>>
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index 2fed935..fdcd683 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -137,12 +137,14 @@ enum lru_list {
>> LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
>> LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
>> LRU_UNEVICTABLE,
>> - NR_LRU_LISTS
>> + NR_LRU_LISTS,
>> + NR_EVICTABLE_LRU_LISTS = LRU_UNEVICTABLE,
>> };
>>
>> #define for_each_lru(lru) for (lru = 0; lru< NR_LRU_LISTS; lru++)
>>
>> -#define for_each_evictable_lru(lru) for (lru = 0; lru<= LRU_ACTIVE_FILE; lru++)
>> +#define for_each_evictable_lru(lru) \
>> + for (lru = 0; lru< NR_EVICTABLE_LRU_LISTS; lru++)
>>
>> static inline int is_file_lru(enum lru_list lru)
>> {
>> @@ -165,11 +167,8 @@ struct zone_reclaim_stat {
>> * mem/swap backed and file backed pages are refeferenced.
>> * The higher the rotated/scanned ratio, the more valuable
>> * that cache is.
>> - *
>> - * The anon LRU stats live in [0], file LRU stats in [1]
>> */
>> - unsigned long recent_rotated[2];
>> - unsigned long recent_scanned[2];
>> + unsigned long recent_rotated[NR_EVICTABLE_LRU_LISTS];
>> };
>>
>> struct lruvec {
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index aeebb9e..2809531 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -4189,26 +4189,31 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
>>
>> #ifdef CONFIG_DEBUG_VM
>> {
>> - int nid, zid;
>> + int nid, zid, lru;
>> struct mem_cgroup_per_zone *mz;
>> struct zone_reclaim_stat *rstat;
>> - unsigned long recent_rotated[2] = {0, 0};
>> - unsigned long recent_scanned[2] = {0, 0};
>> + unsigned long recent_rotated[NR_EVICTABLE_LRU_LISTS];
>>
>> + memset(recent_rotated, 0, sizeof(recent_rotated));
>> for_each_online_node(nid)
>> for (zid = 0; zid< MAX_NR_ZONES; zid++) {
>> mz = mem_cgroup_zoneinfo(memcg, nid, zid);
>> rstat =&mz->lruvec.reclaim_stat;
>> -
>> - recent_rotated[0] += rstat->recent_rotated[0];
>> - recent_rotated[1] += rstat->recent_rotated[1];
>> - recent_scanned[0] += rstat->recent_scanned[0];
>> - recent_scanned[1] += rstat->recent_scanned[1];
>> + for_each_evictable_lru(lru)
>> + recent_rotated[lru] +=
>> + rstat->recent_rotated[lru];
>> }
>> - cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
>> - cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
>> - cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
>> - cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
>> +
>> + cb->fill(cb, "recent_rotated_anon",
>> + recent_rotated[LRU_ACTIVE_ANON]);
>> + cb->fill(cb, "recent_rotated_file",
>> + recent_rotated[LRU_ACTIVE_FILE]);
>> + cb->fill(cb, "recent_scanned_anon",
>> + recent_rotated[LRU_ACTIVE_ANON] +
>> + recent_rotated[LRU_INACTIVE_ANON]);
>> + cb->fill(cb, "recent_scanned_file",
>> + recent_rotated[LRU_ACTIVE_FILE] +
>> + recent_rotated[LRU_INACTIVE_FILE]);
>> }
>> #endif
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index ab2d210..ea40034 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -4365,10 +4365,8 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
>> zone_pcp_init(zone);
>> for_each_lru(lru)
>> INIT_LIST_HEAD(&zone->lruvec.lists[lru]);
>> - zone->lruvec.reclaim_stat.recent_rotated[0] = 0;
>> - zone->lruvec.reclaim_stat.recent_rotated[1] = 0;
>> - zone->lruvec.reclaim_stat.recent_scanned[0] = 0;
>> - zone->lruvec.reclaim_stat.recent_scanned[1] = 0;
>> + memset(&zone->lruvec.reclaim_stat, 0,
>> + sizeof(struct zone_reclaim_stat));
>> zap_zone_vm_stats(zone);
>> zone->flags = 0;
>> if (!size)
>> diff --git a/mm/swap.c b/mm/swap.c
>> index 9a6850b..c7bcde7 100644
>> --- a/mm/swap.c
>> +++ b/mm/swap.c
>> @@ -277,7 +277,7 @@ void rotate_reclaimable_page(struct page *page)
>> }
>>
>> static void update_page_reclaim_stat(struct zone *zone, struct page *page,
>> - int file, int rotated)
>> + enum lru_list lru)
>> {
>> struct zone_reclaim_stat *reclaim_stat;
>>
>> @@ -285,9 +285,7 @@ static void update_page_reclaim_stat(struct zone *zone, struct page *page,
>> if (!reclaim_stat)
>> reclaim_stat =&zone->lruvec.reclaim_stat;
>>
>> - reclaim_stat->recent_scanned[file]++;
>> - if (rotated)
>> - reclaim_stat->recent_rotated[file]++;
>> + reclaim_stat->recent_rotated[lru]++;
>> }
>>
>> static void __activate_page(struct page *page, void *arg)
>> @@ -295,7 +293,6 @@ static void __activate_page(struct page *page, void *arg)
>> struct zone *zone = page_zone(page);
>>
>> if (PageLRU(page)&& !PageActive(page)&& !PageUnevictable(page)) {
>> - int file = page_is_file_cache(page);
>> int lru = page_lru_base_type(page);
>> del_page_from_lru_list(zone, page, lru);
>>
>> @@ -304,7 +301,7 @@ static void __activate_page(struct page *page, void *arg)
>> add_page_to_lru_list(zone, page, lru);
>> __count_vm_event(PGACTIVATE);
>>
>> - update_page_reclaim_stat(zone, page, file, 1);
>> + update_page_reclaim_stat(zone, page, lru);
>> }
>> }
>>
>> @@ -482,7 +479,7 @@ static void lru_deactivate_fn(struct page *page, void *arg)
>>
>> if (active)
>> __count_vm_event(PGDEACTIVATE);
>> - update_page_reclaim_stat(zone, page, file, 0);
>> + update_page_reclaim_stat(zone, page, lru);
>> }
>>
>> /*
>> @@ -646,9 +643,7 @@ EXPORT_SYMBOL(__pagevec_release);
>> void lru_add_page_tail(struct zone* zone,
>> struct page *page, struct page *page_tail)
>> {
>> - int active;
>> enum lru_list lru;
>> - const int file = 0;
>>
>> VM_BUG_ON(!PageHead(page));
>> VM_BUG_ON(PageCompound(page_tail));
>> @@ -660,13 +655,10 @@ void lru_add_page_tail(struct zone* zone,
>> if (page_evictable(page_tail, NULL)) {
>> if (PageActive(page)) {
>> SetPageActive(page_tail);
>> - active = 1;
>> lru = LRU_ACTIVE_ANON;
>> - } else {
>> - active = 0;
>> + } else
>> lru = LRU_INACTIVE_ANON;
>> - }
>> - update_page_reclaim_stat(zone, page_tail, file, active);
>> + update_page_reclaim_stat(zone, page_tail, lru);
>> } else {
>> SetPageUnevictable(page_tail);
>> lru = LRU_UNEVICTABLE;
>> @@ -694,17 +686,15 @@ static void __pagevec_lru_add_fn(struct page *page, void *arg)
>> {
>> enum lru_list lru = (enum lru_list)arg;
>> struct zone *zone = page_zone(page);
>> - int file = is_file_lru(lru);
>> - int active = is_active_lru(lru);
>>
>> VM_BUG_ON(PageActive(page));
>> VM_BUG_ON(PageUnevictable(page));
>> VM_BUG_ON(PageLRU(page));
>>
>> SetPageLRU(page);
>> - if (active)
>> + if (is_active_lru(lru))
>> SetPageActive(page);
>> - update_page_reclaim_stat(zone, page, file, active);
>> + update_page_reclaim_stat(zone, page, lru);
>> add_page_to_lru_list(zone, page, lru);
>> }
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 483b98e..fe00a22 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1355,11 +1355,7 @@ putback_inactive_pages(struct mem_cgroup_zone *mz,
>> SetPageLRU(page);
>> lru = page_lru(page);
>> add_page_to_lru_list(zone, page, lru);
>> - if (is_active_lru(lru)) {
>> - int file = is_file_lru(lru);
>> - int numpages = hpage_nr_pages(page);
>> - reclaim_stat->recent_rotated[file] += numpages;
>> - }
>> + reclaim_stat->recent_rotated[lru] += hpage_nr_pages(page);
>> if (put_page_testzero(page)) {
>> __ClearPageLRU(page);
>> __ClearPageActive(page);
>> @@ -1543,8 +1539,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
>>
>> spin_lock_irq(&zone->lru_lock);
>>
>> - reclaim_stat->recent_scanned[0] += nr_anon;
>> - reclaim_stat->recent_scanned[1] += nr_file;
>> + /*
>> + * Count reclaimed pages as rotated, this helps balance scan pressure
>> + * between file and anonymous pages in get_scan_ratio.
>> + */
>> + reclaim_stat->recent_rotated[lru] += nr_reclaimed;
>>
>> if (current_is_kswapd())
>> __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
>> @@ -1685,8 +1684,6 @@ static void shrink_active_list(unsigned long nr_to_scan,
>> if (global_reclaim(sc))
>> zone->pages_scanned += nr_scanned;
>>
>> - reclaim_stat->recent_scanned[file] += nr_taken;
>> -
>> __count_zone_vm_events(PGREFILL, zone, nr_scanned);
>> __mod_zone_page_state(zone, NR_LRU_BASE + lru, -nr_taken);
>> __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
>> @@ -1742,7 +1739,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>> * helps balance scan pressure between file and anonymous pages in
>> * get_scan_ratio.
>> */
>> - reclaim_stat->recent_rotated[file] += nr_rotated;
>> + reclaim_stat->recent_rotated[lru] += nr_rotated;
>>
>> move_active_pages_to_lru(zone,&l_active,&l_hold, lru);
>> move_active_pages_to_lru(zone,&l_inactive,&l_hold, lru - LRU_ACTIVE);
>> @@ -1875,6 +1872,7 @@ static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc,
>> unsigned long anon_prio, file_prio;
>> unsigned long ap, fp;
>> struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
>> + unsigned long *recent_rotated = reclaim_stat->recent_rotated;
>> u64 fraction[2], denominator;
>> enum lru_list lru;
>> int noswap = 0;
>> @@ -1940,14 +1938,16 @@ static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc,
>> * anon in [0], file in [1]
>> */
>> spin_lock_irq(&mz->zone->lru_lock);
>> - if (unlikely(reclaim_stat->recent_scanned[0]> anon / 4)) {
>> - reclaim_stat->recent_scanned[0] /= 2;
>> - reclaim_stat->recent_rotated[0] /= 2;
>> + if (unlikely(recent_rotated[LRU_INACTIVE_ANON] +
>> + recent_rotated[LRU_ACTIVE_ANON]> anon / 4)) {
>> + recent_rotated[LRU_INACTIVE_ANON] /= 2;
>> + recent_rotated[LRU_ACTIVE_ANON] /= 2;
>> }
>>
>> - if (unlikely(reclaim_stat->recent_scanned[1]> file / 4)) {
>> - reclaim_stat->recent_scanned[1] /= 2;
>> - reclaim_stat->recent_rotated[1] /= 2;
>> + if (unlikely(recent_rotated[LRU_INACTIVE_FILE] +
>> + recent_rotated[LRU_ACTIVE_FILE]> file / 4)) {
>> + recent_rotated[LRU_INACTIVE_FILE] /= 2;
>> + recent_rotated[LRU_ACTIVE_FILE] /= 2;
>> }
>>
>> /*
>> @@ -1955,11 +1955,13 @@ static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc,
>> * proportional to the fraction of recently scanned pages on
>> * each list that were recently referenced and in active use.
>> */
>> - ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1);
>> - ap /= reclaim_stat->recent_rotated[0] + 1;
>> + ap = (anon_prio + 1) * (recent_rotated[LRU_INACTIVE_ANON] +
>> + recent_rotated[LRU_ACTIVE_ANON] + 1);
>> + ap /= recent_rotated[LRU_ACTIVE_ANON] + 1;
>>
>> - fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
>> - fp /= reclaim_stat->recent_rotated[1] + 1;
>> + fp = (file_prio + 1) * (recent_rotated[LRU_INACTIVE_FILE] +
>> + recent_rotated[LRU_ACTIVE_FILE] + 1);
>> + fp /= recent_rotated[LRU_ACTIVE_FILE] + 1;
>> spin_unlock_irq(&mz->zone->lru_lock);
>>
>> fraction[0] = ap;
>>
>>
>
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