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Date: Fri, 18 Feb 2011 09:33:52 +0900 From: Minchan Kim <minchan.kim@...il.com> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, Steven Barrett <damentz@...uorix.net>, Ben Gamari <bgamari.foss@...il.com>, Peter Zijlstra <peterz@...radead.org>, Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, Wu Fengguang <fengguang.wu@...el.com>, Johannes Weiner <hannes@...xchg.org>, Nick Piggin <npiggin@...nel.dk>, Andrea Arcangeli <aarcange@...hat.com>, Balbir Singh <balbir@...ux.vnet.ibm.com> Subject: Re: [PATCH v5 1/4] deactivate invalidated pages On Fri, Feb 18, 2011 at 12:50 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote: > On Fri, 18 Feb 2011 00:08:19 +0900 > Minchan Kim <minchan.kim@...il.com> wrote: > >> Recently, there are reported problem about thrashing. >> (http://marc.info/?l=rsync&m=128885034930933&w=2) >> It happens by backup workloads(ex, nightly rsync). >> That's because the workload makes just use-once pages >> and touches pages twice. It promotes the page into >> active list so that it results in working set page eviction. >> >> Some app developer want to support POSIX_FADV_NOREUSE. >> But other OSes don't support it, either. >> (http://marc.info/?l=linux-mm&m=128928979512086&w=2) >> >> By other approach, app developers use POSIX_FADV_DONTNEED. >> But it has a problem. If kernel meets page is writing >> during invalidate_mapping_pages, it can't work. >> It makes for application programmer to use it since they always >> have to sync data before calling fadivse(..POSIX_FADV_DONTNEED) to >> make sure the pages could be discardable. At last, they can't use >> deferred write of kernel so that they could see performance loss. >> (http://insights.oetiker.ch/linux/fadvise.html) >> >> In fact, invalidation is very big hint to reclaimer. >> It means we don't use the page any more. So let's move >> the writing page into inactive list's head if we can't truncate >> it right now. >> >> Why I move page to head of lru on this patch, Dirty/Writeback page >> would be flushed sooner or later. It can prevent writeout of pageout >> which is less effective than flusher's writeout. >> >> Originally, I reused lru_demote of Peter with some change so added >> his Signed-off-by. >> >> Reported-by: Ben Gamari <bgamari.foss@...il.com> >> Signed-off-by: Minchan Kim <minchan.kim@...il.com> >> Signed-off-by: Peter Zijlstra <peterz@...radead.org> >> Acked-by: Rik van Riel <riel@...hat.com> >> Acked-by: Mel Gorman <mel@....ul.ie> >> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> >> Cc: Wu Fengguang <fengguang.wu@...el.com> >> Cc: Johannes Weiner <hannes@...xchg.org> >> Cc: Nick Piggin <npiggin@...nel.dk> >> Signed-off-by: Minchan Kim <minchan.kim@...il.com> > > > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> > > One question is ....it seems there is no flush() code for percpu pagevec > in this patch. Is it safe against cpu hot plug ? > > And from memory hot unplug point of view, I'm grad if pagevec for this > is flushed at the same time as when we clear other per-cpu lru pagevecs. > (And compaction will be affected by the page_count() magic by pagevec > which is flushed only when FADVISE is called.) > > Could you add add-on patches for flushing and hooks ? Isn't it enough in my patch? If I miss your point, Could you elaborate please? * Drain pages out of the cpu's pagevecs. * Either "cpu" is the current CPU, and preemption has already been * disabled; or "cpu" is being hot-unplugged, and is already dead. @@ -372,6 +427,29 @@ static void drain_cpu_pagevecs(int cpu) pagevec_move_tail(pvec); local_irq_restore(flags); } + + pvec = &per_cpu(lru_deactivate_pvecs, cpu); + if (pagevec_count(pvec)) + ____pagevec_lru_deactivate(pvec); +} > > Thanks, > -Kame > > > >> --- >> Changelog since v4: >> - Change function comments - suggested by Johannes >> - Change function name - suggested by Johannes >> - Drop only dirty/writeback pages to deactive pagevec - suggested by Johannes >> - Add acked-by >> >> Changelog since v3: >> - Change function comments - suggested by Johannes >> - Change function name - suggested by Johannes >> - add only dirty/writeback pages to deactive pagevec >> >> Changelog since v2: >> - mapped page leaves alone - suggested by Mel >> - pass part related PG_reclaim in next patch. >> >> Changelog since v1: >> - modify description >> - correct typo >> - add some comment >> >> include/linux/swap.h | 1 + >> mm/swap.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++ >> mm/truncate.c | 17 ++++++++--- >> 3 files changed, 91 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/swap.h b/include/linux/swap.h >> index 4d55932..c335055 100644 >> --- a/include/linux/swap.h >> +++ b/include/linux/swap.h >> @@ -215,6 +215,7 @@ extern void mark_page_accessed(struct page *); >> extern void lru_add_drain(void); >> extern int lru_add_drain_all(void); >> extern void rotate_reclaimable_page(struct page *page); >> +extern void deactivate_page(struct page *page); >> extern void swap_setup(void); >> >> extern void add_page_to_unevictable_list(struct page *page); >> diff --git a/mm/swap.c b/mm/swap.c >> index c02f936..4aea806 100644 >> --- a/mm/swap.c >> +++ b/mm/swap.c >> @@ -39,6 +39,7 @@ int page_cluster; >> >> static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); >> static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); >> +static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); >> >> /* >> * This path almost never happens for VM activity - pages are normally >> @@ -347,6 +348,60 @@ void add_page_to_unevictable_list(struct page *page) >> } >> >> /* >> + * If the page can not be invalidated, it is moved to the >> + * inactive list to speed up its reclaim. It is moved to the >> + * head of the list, rather than the tail, to give the flusher >> + * threads some time to write it out, as this is much more >> + * effective than the single-page writeout from reclaim. >> + */ >> +static void lru_deactivate(struct page *page, struct zone *zone) >> +{ >> + int lru, file; >> + >> + if (!PageLRU(page) || !PageActive(page)) >> + return; >> + >> + /* Some processes are using the page */ >> + if (page_mapped(page)) >> + return; >> + >> + file = page_is_file_cache(page); >> + lru = page_lru_base_type(page); >> + del_page_from_lru_list(zone, page, lru + LRU_ACTIVE); >> + ClearPageActive(page); >> + ClearPageReferenced(page); >> + add_page_to_lru_list(zone, page, lru); >> + __count_vm_event(PGDEACTIVATE); >> + >> + update_page_reclaim_stat(zone, page, file, 0); >> +} >> + >> +static void ____pagevec_lru_deactivate(struct pagevec *pvec) >> +{ >> + int i; >> + struct zone *zone = NULL; >> + >> + for (i = 0; i < pagevec_count(pvec); i++) { >> + struct page *page = pvec->pages[i]; >> + struct zone *pagezone = page_zone(page); >> + >> + if (pagezone != zone) { >> + if (zone) >> + spin_unlock_irq(&zone->lru_lock); >> + zone = pagezone; >> + spin_lock_irq(&zone->lru_lock); >> + } >> + lru_deactivate(page, zone); >> + } >> + if (zone) >> + spin_unlock_irq(&zone->lru_lock); >> + >> + release_pages(pvec->pages, pvec->nr, pvec->cold); >> + pagevec_reinit(pvec); >> +} >> + >> + >> +/* >> * Drain pages out of the cpu's pagevecs. >> * Either "cpu" is the current CPU, and preemption has already been >> * disabled; or "cpu" is being hot-unplugged, and is already dead. >> @@ -372,6 +427,29 @@ static void drain_cpu_pagevecs(int cpu) >> pagevec_move_tail(pvec); >> local_irq_restore(flags); >> } >> + >> + pvec = &per_cpu(lru_deactivate_pvecs, cpu); >> + if (pagevec_count(pvec)) >> + ____pagevec_lru_deactivate(pvec); >> +} >> + >> +/** >> + * deactivate_page - forcefully deactivate a page >> + * @page: page to deactivate >> + * >> + * This function hints the VM that @page is a good reclaim candidate, >> + * for example if its invalidation fails due to the page being dirty >> + * or under writeback. >> + */ >> +void deactivate_page(struct page *page) >> +{ >> + if (likely(get_page_unless_zero(page))) { >> + struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); >> + >> + if (!pagevec_add(pvec, page)) >> + ____pagevec_lru_deactivate(pvec); >> + put_cpu_var(lru_deactivate_pvecs); >> + } >> } >> >> void lru_add_drain(void) >> diff --git a/mm/truncate.c b/mm/truncate.c >> index 4d415b3..9ec7bc5 100644 >> --- a/mm/truncate.c >> +++ b/mm/truncate.c >> @@ -328,11 +328,12 @@ EXPORT_SYMBOL(truncate_inode_pages); >> * pagetables. >> */ >> unsigned long invalidate_mapping_pages(struct address_space *mapping, >> - pgoff_t start, pgoff_t end) >> + pgoff_t start, pgoff_t end) >> { >> struct pagevec pvec; >> pgoff_t next = start; >> - unsigned long ret = 0; >> + unsigned long ret; >> + unsigned long count = 0; >> int i; >> >> pagevec_init(&pvec, 0); >> @@ -359,8 +360,14 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, >> if (lock_failed) >> continue; >> >> - ret += invalidate_inode_page(page); >> - >> + ret = invalidate_inode_page(page); >> + /* >> + * Invalidation is a hint that the page is no longer >> + * of interest and try to speed up its reclaim. >> + */ >> + if (!ret) >> + deactivate_page(page); >> + count += ret; >> unlock_page(page); >> if (next > end) >> break; >> @@ -369,7 +376,7 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, >> mem_cgroup_uncharge_end(); >> cond_resched(); >> } >> - return ret; >> + return count; >> } >> EXPORT_SYMBOL(invalidate_mapping_pages); >> >> -- >> 1.7.1 >> >> > > -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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