On Sun, Nov 21, 2010 at 11:30:23PM +0900, Minchan Kim 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 developer uses POSIX_FADV_DONTNEED. > But it has a problem. If kernel meets page is writing > during invalidate_mapping_pages, it can't work. > It is very hard for application programmer to use it. > Because 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, invalidate 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 it is real working set, it could have a enough time to > activate the page since we always try to keep many pages in > inactive list. > > I reuse lru_demote of Peter with some change. > > Reported-by: Ben Gamari <bgamari.foss@xxxxxxxxx> > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> > Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Nick Piggin <npiggin@xxxxxxxxx> > > Ben, Remain thing is to modify rsync and use > fadvise(POSIX_FADV_DONTNEED). Could you test it? > --- > include/linux/swap.h | 1 + > mm/swap.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++ > mm/truncate.c | 11 +++++--- > 3 files changed, 69 insertions(+), 4 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index eba53e7..a3c9248 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -213,6 +213,7 @@ 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 lru_deactive_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 3f48542..56fa298 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -39,6 +39,8 @@ 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_deactive_pvecs); > + > > /* > * This path almost never happens for VM activity - pages are normally > @@ -266,6 +268,45 @@ void add_page_to_unevictable_list(struct page *page) > spin_unlock_irq(&zone->lru_lock); > } > > +static void __pagevec_lru_deactive(struct pagevec *pvec) > +{ Might be worth commenting that this function must be called with pre-emption disabled. FWIW, I am reasonably sure your implementation is prefectly safe but a note wouldn't hurt. > + int i, lru, file; > + > + 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); > + } > + > + if (PageLRU(page)) { > + if (PageActive(page)) { > + 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); > + What about memcg, do we not need to be calling mem_cgroup_add_lru_list() here as well? I'm looking at the differences between what move_active_pages_to_lru() is doing and this. I'm wondering if it'd be worth your whole building a list of active pages that are to be moved to the inactive list and passing them to move_active_pages_to_lru() ? I confuess I have not thought about it deeply so it might be a terrible suggestion but it might reduce duplication of code. > + update_page_reclaim_stat(zone, page, file, 0); > + } > + } > + } > + 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 > @@ -292,8 +333,28 @@ static void drain_cpu_pagevecs(int cpu) > pagevec_move_tail(pvec); > local_irq_restore(flags); > } > + > + pvec = &per_cpu(lru_deactive_pvecs, cpu); > + if (pagevec_count(pvec)) > + __pagevec_lru_deactive(pvec); > +} > + > +/* > + * Function used to forecefully demote a page to the head of the inactive > + * list. s/forecefully/forcefully/ The comment should also state *why* and under what circumstances we move pages to the inactive list like this. Also based on the discussions elsewhere in this thread, it'd be nice to include a comment why it's the head of the inactive list and not the tail. > + */ > +void lru_deactive_page(struct page *page) > +{ > + if (likely(get_page_unless_zero(page))) { > + struct pagevec *pvec = &get_cpu_var(lru_deactive_pvecs); > + > + if (!pagevec_add(pvec, page)) > + __pagevec_lru_deactive(pvec); > + put_cpu_var(lru_deactive_pvecs); > + } > } > > + > void lru_add_drain(void) > { > drain_cpu_pagevecs(get_cpu()); > diff --git a/mm/truncate.c b/mm/truncate.c > index cd94607..c73fb19 100644 > --- a/mm/truncate.c > +++ b/mm/truncate.c > @@ -332,7 +332,8 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, > { > 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 +360,10 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, > if (lock_failed) > continue; > > - ret += invalidate_inode_page(page); > - > + ret = invalidate_inode_page(page); > + if (!ret) > + lru_deactive_page(page); > + count += ret; > unlock_page(page); > if (next > end) > break; > @@ -369,7 +372,7 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, > mem_cgroup_uncharge_end(); > cond_resched(); > } > - return ret; > + return count; > } > EXPORT_SYMBOL(invalidate_mapping_pages); > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . 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