by KOSAKI Motohiro

[permalink] [raw]

Subject: Re: [PATCH 1/4] vmscan: more simplify shrink_inactive_list()

> Hi KOSAKI,
>
> It would be easier to review if you can split the changes and the big
> "unshift" :)

Umm. I don't like break checkpatch.pl rule ;)
if you have enough time, can you please use diff -b yourself?

> Otherwise it looks good to me. (actually I've advocated it before ;)
>
> Thanks,
> Fengguang
>
> On Fri, Nov 27, 2009 at 09:17:48AM +0900, KOSAKI Motohiro wrote:
> > This patch depend on "vmscan : simplify code" patch (written by Huang Shijie)
> >
> > =========================================
> > Now, max_scan of shrink_inactive_list() is always passed less than
> > SWAP_CLUSTER_MAX. then, we can remove scanning pages loop in it.
> >
> > detail
> > - remove "while (nr_scanned < max_scan)" loop
> > - remove nr_freed variable (now, we use nr_reclaimed directly)
> > - remove nr_scan variable (now, we use nr_scanned directly)
> > - rename max_scan to nr_to_scan
> > - pass nr_to_scan into isolate_pages() directly instead
> > using SWAP_CLUSTER_MAX
> >
> > Signed-off-by: KOSAKI Motohiro <[email protected]>
> > ---
> > mm/vmscan.c | 194 ++++++++++++++++++++++++++++-------------------------------
> > 1 files changed, 91 insertions(+), 103 deletions(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 7536991..a58ff15 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1085,16 +1085,22 @@ static int too_many_isolated(struct zone *zone, int file,
> > * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
> > * of reclaimed pages
> > */
> > -static unsigned long shrink_inactive_list(unsigned long max_scan,
> > - struct zone *zone, struct scan_control *sc,
> > - int priority, int file)
> > +static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> > + struct zone *zone, struct scan_control *sc,
> > + int priority, int file)
> > {
> > LIST_HEAD(page_list);
> > struct pagevec pvec;
> > - unsigned long nr_scanned = 0;
> > + unsigned long nr_scanned;
> > unsigned long nr_reclaimed = 0;
> > struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> > int lumpy_reclaim = 0;
> > + struct page *page;
> > + unsigned long nr_taken;
> > + unsigned long nr_active;
> > + unsigned int count[NR_LRU_LISTS] = { 0, };
> > + unsigned long nr_anon;
> > + unsigned long nr_file;
> >
> > while (unlikely(too_many_isolated(zone, file, sc))) {
> > congestion_wait(BLK_RW_ASYNC, HZ/10);
> > @@ -1120,119 +1126,101 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
> >
> > lru_add_drain();
> > spin_lock_irq(&zone->lru_lock);
> > - do {
> > - struct page *page;
> > - unsigned long nr_taken;
> > - unsigned long nr_scan;
> > - unsigned long nr_freed;
> > - unsigned long nr_active;
> > - unsigned int count[NR_LRU_LISTS] = { 0, };
> > - int mode = lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE;
> > - unsigned long nr_anon;
> > - unsigned long nr_file;
> > -
> > - nr_taken = sc->isolate_pages(SWAP_CLUSTER_MAX,
> > - &page_list, &nr_scan, sc->order, mode,
> > - zone, sc->mem_cgroup, 0, file);
> > + nr_taken = sc->isolate_pages(nr_to_scan,
> > + &page_list, &nr_scanned, sc->order,
> > + lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE,
> > + zone, sc->mem_cgroup, 0, file);
> >
> > - if (scanning_global_lru(sc)) {
> > - zone->pages_scanned += nr_scan;
> > - if (current_is_kswapd())
> > - __count_zone_vm_events(PGSCAN_KSWAPD, zone,
> > - nr_scan);
> > - else
> > - __count_zone_vm_events(PGSCAN_DIRECT, zone,
> > - nr_scan);
> > - }
> > + if (scanning_global_lru(sc)) {
> > + zone->pages_scanned += nr_scanned;
> > + if (current_is_kswapd())
> > + __count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned);
> > + else
> > + __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned);
> > + }
> >
> > - if (nr_taken == 0)
> > - goto done;
> > + if (nr_taken == 0)
> > + goto done;
> >
> > - nr_active = clear_active_flags(&page_list, count);
> > - __count_vm_events(PGDEACTIVATE, nr_active);
> > + nr_active = clear_active_flags(&page_list, count);
> > + __count_vm_events(PGDEACTIVATE, nr_active);
> >
> > - __mod_zone_page_state(zone, NR_ACTIVE_FILE,
> > - -count[LRU_ACTIVE_FILE]);
> > - __mod_zone_page_state(zone, NR_INACTIVE_FILE,
> > - -count[LRU_INACTIVE_FILE]);
> > - __mod_zone_page_state(zone, NR_ACTIVE_ANON,
> > - -count[LRU_ACTIVE_ANON]);
> > - __mod_zone_page_state(zone, NR_INACTIVE_ANON,
> > - -count[LRU_INACTIVE_ANON]);
> > + __mod_zone_page_state(zone, NR_ACTIVE_FILE,
> > + -count[LRU_ACTIVE_FILE]);
> > + __mod_zone_page_state(zone, NR_INACTIVE_FILE,
> > + -count[LRU_INACTIVE_FILE]);
> > + __mod_zone_page_state(zone, NR_ACTIVE_ANON,
> > + -count[LRU_ACTIVE_ANON]);
> > + __mod_zone_page_state(zone, NR_INACTIVE_ANON,
> > + -count[LRU_INACTIVE_ANON]);
> >
> > - nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
> > - nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
> > - __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
> > - __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
> > + nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
> > + nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
> > + __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
> > + __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
> >
> > - reclaim_stat->recent_scanned[0] += nr_anon;
> > - reclaim_stat->recent_scanned[1] += nr_file;
> > + reclaim_stat->recent_scanned[0] += nr_anon;
> > + reclaim_stat->recent_scanned[1] += nr_file;
> >
> > - spin_unlock_irq(&zone->lru_lock);
> > + spin_unlock_irq(&zone->lru_lock);
> >
> > - nr_scanned += nr_scan;
> > - nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
> > + nr_reclaimed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
> > +
> > + /*
> > + * If we are direct reclaiming for contiguous pages and we do
> > + * not reclaim everything in the list, try again and wait
> > + * for IO to complete. This will stall high-order allocations
> > + * but that should be acceptable to the caller
> > + */
> > + if (nr_reclaimed < nr_taken && !current_is_kswapd() && lumpy_reclaim) {
> > + congestion_wait(BLK_RW_ASYNC, HZ/10);
> >
> > /*
> > - * If we are direct reclaiming for contiguous pages and we do
> > - * not reclaim everything in the list, try again and wait
> > - * for IO to complete. This will stall high-order allocations
> > - * but that should be acceptable to the caller
> > + * The attempt at page out may have made some
> > + * of the pages active, mark them inactive again.
> > */
> > - if (nr_freed < nr_taken && !current_is_kswapd() &&
> > - lumpy_reclaim) {
> > - congestion_wait(BLK_RW_ASYNC, HZ/10);
> > -
> > - /*
> > - * The attempt at page out may have made some
> > - * of the pages active, mark them inactive again.
> > - */
> > - nr_active = clear_active_flags(&page_list, count);
> > - count_vm_events(PGDEACTIVATE, nr_active);
> > -
> > - nr_freed += shrink_page_list(&page_list, sc,
> > - PAGEOUT_IO_SYNC);
> > - }
> > + nr_active = clear_active_flags(&page_list, count);
> > + count_vm_events(PGDEACTIVATE, nr_active);
> >
> > - nr_reclaimed += nr_freed;
> > + nr_reclaimed += shrink_page_list(&page_list, sc,
> > + PAGEOUT_IO_SYNC);
> > + }
> >
> > - local_irq_disable();
> > - if (current_is_kswapd())
> > - __count_vm_events(KSWAPD_STEAL, nr_freed);
> > - __count_zone_vm_events(PGSTEAL, zone, nr_freed);
> > + local_irq_disable();
> > + if (current_is_kswapd())
> > + __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
> > + __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
> >
> > - spin_lock(&zone->lru_lock);
> > - /*
> > - * Put back any unfreeable pages.
> > - */
> > - while (!list_empty(&page_list)) {
> > - int lru;
> > - page = lru_to_page(&page_list);
> > - VM_BUG_ON(PageLRU(page));
> > - list_del(&page->lru);
> > - if (unlikely(!page_evictable(page, NULL))) {
> > - spin_unlock_irq(&zone->lru_lock);
> > - putback_lru_page(page);
> > - spin_lock_irq(&zone->lru_lock);
> > - continue;
> > - }
> > - 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);
> > - reclaim_stat->recent_rotated[file]++;
> > - }
> > - if (!pagevec_add(&pvec, page)) {
> > - spin_unlock_irq(&zone->lru_lock);
> > - __pagevec_release(&pvec);
> > - spin_lock_irq(&zone->lru_lock);
> > - }
> > + spin_lock(&zone->lru_lock);
> > + /*
> > + * Put back any unfreeable pages.
> > + */
> > + while (!list_empty(&page_list)) {
> > + int lru;
> > + page = lru_to_page(&page_list);
> > + VM_BUG_ON(PageLRU(page));
> > + list_del(&page->lru);
> > + if (unlikely(!page_evictable(page, NULL))) {
> > + spin_unlock_irq(&zone->lru_lock);
> > + putback_lru_page(page);
> > + spin_lock_irq(&zone->lru_lock);
> > + continue;
> > }
> > - __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> > - __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> > -
> > - } while (nr_scanned < max_scan);
> > + 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);
> > + reclaim_stat->recent_rotated[file]++;
> > + }
> > + if (!pagevec_add(&pvec, page)) {
> > + spin_unlock_irq(&zone->lru_lock);
> > + __pagevec_release(&pvec);
> > + spin_lock_irq(&zone->lru_lock);
> > + }
> > + }
> > + __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> > + __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> >
> > done:
> > spin_unlock_irq(&zone->lru_lock);
> > --
> > 1.6.5.2
> >
> >
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to [email protected]. For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

2009-12-07 06:17:46

by KOSAKI Motohiro

[permalink] [raw]

Subject: Re: [PATCH] vmscan: aligned scan batching

> > - pass nr_to_scan into isolate_pages() directly instead
> > using SWAP_CLUSTER_MAX
>
> This patch will make sure nr_to_scan==SWAP_CLUSTER_MAX :)
>
> Thanks,
> Fengguang
> ---
> vmscan: aligned scan batching
>
> Make sure ->isolate_pages() always scans in unit of SWAP_CLUSTER_MAX.
>
> CC: Rik van Riel <[email protected]>
> CC: KOSAKI Motohiro <[email protected]>
> Signed-off-by: Wu Fengguang <[email protected]>
> ---
> mm/vmscan.c | 20 ++++++--------------
> 1 file changed, 6 insertions(+), 14 deletions(-)

Hm, Your patch always pass SWAP_CLUSTER_MAX to shrink_list().
Can we remove nr_to_scan argument of shrink_list() completely?

Anyway, this diffstat itsef explain this patch's worth. I'll queue
this patch into my vmscan cleanup branch.

>
> --- linux-mm.orig/mm/vmscan.c 2009-12-06 13:13:28.000000000 +0800
> +++ linux-mm/mm/vmscan.c 2009-12-06 13:31:21.000000000 +0800
> @@ -1572,15 +1572,11 @@ static void get_scan_ratio(struct zone *
> static unsigned long nr_scan_try_batch(unsigned long nr_to_scan,
> unsigned long *nr_saved_scan)
> {
> - unsigned long nr;
> + unsigned long nr = *nr_saved_scan + nr_to_scan;
> + unsigned long rem = nr & (SWAP_CLUSTER_MAX - 1);
>
> - *nr_saved_scan += nr_to_scan;
> - nr = *nr_saved_scan;
> -
> - if (nr >= SWAP_CLUSTER_MAX)
> - *nr_saved_scan = 0;
> - else
> - nr = 0;
> + *nr_saved_scan = rem;
> + nr -= rem;
>
> return nr;
> }
> @@ -1592,7 +1588,6 @@ static void shrink_zone(int priority, st
> struct scan_control *sc)
> {
> unsigned long nr[NR_LRU_LISTS];
> - unsigned long nr_to_scan;
> unsigned long percent[2]; /* anon @ 0; file @ 1 */
> enum lru_list l;
> unsigned long nr_reclaimed = sc->nr_reclaimed;
> @@ -1625,11 +1620,8 @@ static void shrink_zone(int priority, st
> nr[LRU_INACTIVE_FILE]) {
> for_each_evictable_lru(l) {
> if (nr[l]) {
> - nr_to_scan = min_t(unsigned long,
> - nr[l], SWAP_CLUSTER_MAX);
> - nr[l] -= nr_to_scan;
> -
> - nr_reclaimed += shrink_list(l, nr_to_scan,
> + nr[l] -= SWAP_CLUSTER_MAX;
> + nr_reclaimed += shrink_list(l, SWAP_CLUSTER_MAX,
> zone, sc, priority);
> }
> }